Air is getting into the transmission from around the shaft of the main powervalve or the RHS boost port valve when you're pressurising the cylinder. It's not completely air tight from the crankcase to the powervalve mech which is how it gets oiled from premix. In general operation, compression is made above the powervalve ports and the pressure from combustion would go out the exhaust. That means there was no air leak as you would have known if the RHS seal was blown. You would have been riding a fog machine with spooge everywhere. Good luck finding a replacement powervalve, they're rare as hens teeth.
That is super interesting and makes perfect sense now that you've laid it out for me in such a logical manner. Basically right behind the power valve door we've got the cavity where the actuating rod comes up in other words. I also understand what yourye saying about no spooge. I was wondering how I could have a wet side crank seal leak, but not be burning gobs of transmission oil/ tons of smoke. This is really cool, thank you for the reply. I'm going to pin it in the comments so other people can hopefully find value in it too. What would you inspect next as the cause of damage? The original jetting was fat, each jet one size larger then it should have been for the exhaust combo at sea level. Although I suppose the last owner who mentioned that it didn't feel quite right may have been trying to feed it more fuel to combat the lean condition, but it was already damaged thus rendering that re-jet pointless. So if there was no leak, and there was already damage, it was more of a common wear-out & failure? Thanks for running a clinic JM!
@@mxrevivalno worries. I've been trying to keep my 06 rm250 alive for the last 8 or so years so know it in and out. When you showed that piston top with the broken ring land my first thought was "somebody got the ring gap wrong". I remember you had a nightmare trying to get it started which made me wonder if the timing was too advanced in that video. Did you get any indication of pinging when riding? Right now I think improper assembly was the culprit as it's hard to assess that piston considering the damage. Under the piston crown with a heavy burnt oil patch can be a sign of getting too hot/lean.
2 full wraps, no more than 3,with tape in the direction of tightening, you can add pipe dope on top if u want, it acts as a lubricant to help get the joint tight.
You had 5 wraps?????? I'm a generator technician I install gas lines everyday and I've never had a leak with my joints. That tape had to be garbage, definitely use a pipe dope like blue monster or something to help seal it. 5 wraps is absurd
You’re going to have to inspect the cases really well to make sure there’s no cracks or warpage unless you know for sure it was leaking from the right side crank seal. I would try to verify that before spending time and money rebuilding. Still waiting for the CR500 rebuild…
Totally agree! It could even be something like a nick between the case halves from the cases being split with a screwdriver! I did think it was interesting that it was coming out from behind the sprocket, then realized this Suzuki doesn't have a crankcase breather like the Yamaha. So the air has to come out somewhere.
Ooooffff. That was an expensive day at the track, in 40 years riding mx I've never done the pressure test but now I'm on older bikes it's essential. Great how-to video👌
Thanks G! I am literally building the live I'd like to live... The money part, well that'll come eventually 🙌 I will never stop! Thanks for the killer comment -Charles // mXrevival
You can be leaking from the center case gasket or the right side crank seal. Gotta pull your right side engine cover to confirm it is/is not NOT the seal. The powervalve seal on the side of the jug cam let air into the transmission as well. So the case gasket & seals could all be fine but it's leaking fromt the powervalve seal area. But thay piston is broken. Not blown up. That was detonation that broke the ringland off. The detonation pushed the edge of the piston down under combustion, (pinching the ring). On the way back down, the rings snagged on a port getting bent up & breaking the edge of the piston off. Then as it went to TDC, the broken parts & ring chunks got smashed into the head. What was your fuel grade? Where was the timing in comparison to the "stock" setting? What was the quench height? A bad head cut will cause detonation. What was the scenario when it died? But that was detonation 💯% man. Edit: Ditch the rad valve for the STOCK cage & reed petals & instal a reed spacer. You'll have more power & better power. Lots of experience & dyno time building engines. Had an 06 rm250 as a personal bike in the stable for a number of years. It's one of my favorite bikes....all time.
*_Keith, I LOVE this reply. It's too bad I can only pin one comment at a time! In response to your questions:_* You can be leaking from the center case gasket or the right side crank seal. Gotta pull your right side engine cover to confirm it is/is not NOT the seal. *_Understood, and makes more sense at JonnoMoto said that I likely don't have a leak. No excessive smoke trans oil coming out of the pipe. I was somewhat stumped on that in the video._* The powervalve seal on the side of the jug cam let air into the transmission as well. So the case gasket & seals could all be fine but it's leaking fromt the powervalve seal area. *_Jonno mentioned this too. it makes perfect sense. The air has to come out somewhere in the end so the countershaft seal it is... This threw me off as I also thought maybe a breech between cases but same scenario as the right side crank seal IF it was actually leaking. Jonno suggesting there was no leak makes the most sense now. Funny how I forced the video to that conclusion just because I was hell bent on the leak down tester proving something. I did not do a very good job on this video & should not have rushed things to wrap up._* But thay piston is broken. Not blown up. That was detonation that broke the ringland off. The detonation pushed the edge of the piston down under combustion, (pinching the ring). On the way back down, the rings snagged on a port getting bent up & breaking the edge of the piston off. Then as it went to TDC, the broken parts & ring chunks got smashed into the head. *_Regarding the lingo (blown up) may I ask the difference when speaking technically? I was using the term blown-up very generically as it could be searched & SEO optimized, or basically understood by most that "there's a problem" of some sort going on here 😂 Thank you for the detonation explanation, I can visualize it all occurring step by step & that is helpful for me._ * *_Before I answer these, it almost seems safe to say that most of the damage was already done here as I only logged about 45 minutes on the bike in a few short motos. It was the first time I ever rode it. The bike felt lean or soft, like when a main jet is too small and engine wants more fuel to reach higher RMPs._* What was your fuel grade? *_101 @ 40:1 always_* Where was the timing in comparison to the "stock" setting? *_Unsure, but the stator plate is in the identical location/ orientation as my healthy 04 engine when looking at both side by side._* What was the quench height? A bad head cut will cause detonation. *_Unfamiliar with the term & eagerly awaiting more info! Did you ever see "Short Circuit" where the robot Johnny 5 is always begging for "input"?? Call me Johnny!!_* What was the scenario when it died? *_It ran until it sort of shut off as I rolled up to the truck. I got off the track because I felt the power degrade to a un-useable level & had to keep it alive by blipping the throttle liberally. The soft power it had before that VS the "tale your arms off" RM power I expected makes it seem like I simply finished off a coffin that was almost fully nailed shut._* But that was detonation 💯% man. Edit: Ditch the rad valve for the STOCK cage & reed petals & instal a reed spacer. You'll have more power & better power. Lots of experience & dyno time building engines. Had an 06 rm250 as a personal bike in the stable for a number of years. It's one of my favorite bikes....all time. *_Ok! I will have to track down an OEM & try it sometime. I have the Vforce & Boyesen as they came with both RM's when purchased. Me too bro, I adore these old RM's which to me don't really feel old yet_*
@@mxrevival I totally remember that movie short circuit & Johnny 5's hunger for input! I wish I could read like Johnny 5! Lol So for the input, there are 2 parts of the head. There's the dome area which is the deep pocket around the sparkplug. Then there's the shallow area around the outside of the dome. This is the "squish band" area. It is measured in 2 ways. 1 is the length of the squish band. This is simply a measurement from the edge of the dome, across the squishband to the cylinder wall or outside diameter of the head. The 2nd measurement, called the "quench" area, is a height measurement & its done from the outside of the "squish band" area of the head to the outside edge of the piston at Top Dead Center. It's the gap between the piston & the squishband area of the head when the piston is at TDC. Measure this with a piece of solder & make sure you do it IN LINE with the piston pin or the sides of the piston by the transfer ports. The reason is to avoid piston "rock" that happens it the measurement is done on the intake or exhaust side of the piston. This would give a false measurement & also give a potentially false notion of the head being cut at a poor angle vs the angle on the crown/dome of the piston. You want to match the angle of the piston dome with the squishband area of the head or have the head about 1/2 a degree steeper than the piston angle. Bad scenarios would be if the squishband cut in the head is flatter than the piston dome shape. Think of a flat top head design with a dome piston. This will make a triangle pocket around the outside of the piston which will undoubtedly cause detonation. This is the worst. The measurement for "quench" is that distance between the piston & the squishband. A tall squish, which these bikes (& most) have, is actually a bad thing for detonation. The tall area takes longer for the flame front to reach out to the edges of the cylinder. This tall & slower moving flame front area allows heat (from it) to radiate forward & light off the fuel around the outside edge in the squish band. Now that fuel is burning inward toward the dome & the burning fuel from the done is burning outward. These two fronts collide around the outside of the piston & in the squish area. This excessive pressure happens over the ringland area which smashes the piston edge down on the ring, pinching the ring. The ring no longer floats & can now snag a port on its way past. This happens on its way down from TDC & folds both the ring & piston up breaking off the edge of the piston & tearing up the ring. Then on the way back up, the ring tears up the jug & all of the debris gets smashed into the head. The few extra revolutions the engine makes (from momentum) after the catastrophe are to just make sure it's good & junk. Lol Anyway, a tight quench is way better for staving off detonation. The shorter flame front heading from the dome to the outside of the cylinder is moving faster & has a shorter heat gradient (less tall which means less surface area to throw heat). This faster moving flame front doesn't have as much time to light the unburned mixture out in the squish area thus staving off detonation better than a tall quench or squishband. So a short squish (quench area) can safely & happily run on lower octane fuel but still have higher compression than a tall squish (quench area) build will tolerate. I hope I worded all that in a comprehensible way. On a brighter note, if the head was cut (poorly), it's now junk so you won't have to worry about it being the problem if it was. 😁 Besides a pressure test, a vacuum test should also be done. A seal can leak one way but not the other. Both are bad. So I'd still confirm the case halves aren't leaking by removing the right side cover by dropping the jug back on with a base gasket (don't even need a piston in it) & try to seal the powervalve area's to confirm the bottom is air tight....or not. Don't exceed 7psi on both vacuume & pressuretesting. Anymore & some seals can get the lips flipped &/or get pushed out. Your fuel octane is legit & the timing seems NOT to be the culprit judging by the stator being like the other bike which has a known reliable engine. Detonation sounds like a bag of marbles getting banged around inside the engine. It has a sort of rattling sound & the engine can only handle it for a very brief time. Like only a couple seconds & junk. Besides a lean main jet, a lean needle setting can cause it as well.
I totally remember that movie short circuit & Johnny 5's hunger for input! I wish I could read like Johnny 5! Lol *_Hahahaha, "Steee-pha-neeee" no dissasemble..._* So for the input, there are 2 parts of the head. There's the dome area which is the deep pocket around the sparkplug. Then there's the shallow area around the outside of the dome. This is the "squish band" area. It is measured in 2 ways. 1 is the length of the squish band. This is simply a measurement from the edge of the dome, across the squishband to the cylinder wall or outside diameter of the head. The 2nd measurement, called the "quench" area, is a height measurement & its done from the outside of the "squish band" area of the head to the outside edge of the piston at Top Dead Center. It's the gap between the piston & the squishband area of the head when the piston is at TDC. *_Ok awesome, I have always wanted to try the hollow-core solder trick to check squish but have not yet, and always ran what I had when doing top ends. Sounds like I'd be able to figure out if this head has been cut or modified in doing this too, if I knew what the stock squish was from a confirmed stock head. I'd love to know the limitations & have been doing some homework to become a better educator down the road._* Measure this with a piece of solder & make sure you do it IN LINE with the piston pin or the sides of the piston by the transfer ports. The reason is to avoid piston "rock" that happens it the measurement is done on the intake or exhaust side of the piston. This would give a false measurement & also give a potentially false notion of the head being cut at a poor angle vs the angle on the crown/dome of the piston. You want to match the angle of the piston dome with the squishband area of the head or have the head about 1/2 a degree steeper than the piston angle. *I should read the entire post before I reply 😂* Bad scenarios would be if the squishband cut in the head is flatter than the piston dome shape. Think of a flat top head design with a dome piston. This will make a triangle pocket around the outside of the piston which will undoubtedly cause detonation. This is the worst. *_Ahh, I see. So the squish band should follow the curvature (or not) of the intended piston for said engine. They are parallel to each other in easy terms, or for lack of a more technical way for me to explain it? Why does it cause detonation? (thank you)_* The measurement for "quench" is that distance between the piston & the squishband. A tall squish, which these bikes (& most) have, is actually a bad thing for detonation. The tall area takes longer for the flame front to reach out to the edges of the cylinder. This tall & slower moving flame front area allows heat (from it) to radiate forward & light off the fuel around the outside edge in the squish band. Now that fuel is burning inward toward the dome & the burning fuel from the done is burning outward. These two fronts collide around the outside of the piston & in the squish area. This excessive pressure happens over the ringland area which smashes the piston edge down on the ring, pinching the ring. The ring no longer floats & can now snag a port on its way past. This happens on its way down from TDC & folds both the ring & piston up breaking off the edge of the piston & tearing up the ring. Then on the way back up, the ring tears up the jug & all of the debris gets smashed into the head. The few extra revolutions the engine makes (from momentum) after the catastrophe are to just make sure it's good & junk. *_Lol Well isn't that just dandy?? Good explanation of what I have seen the result of now!! 😂 I understand! So it sounds like modifying the stock head for a tighter squish clearance or purchasing an aftermarket head (which must be why these are made) is how to correct the issue, not taking into account a cylinder base gasket height but in general a remedy to the problem?_* Anyway, a tight quench is way better for staving off detonation. The shorter flame front heading from the dome to the outside of the cylinder is moving faster & has a shorter heat gradient (less tall which means less surface area to throw heat). This faster moving flame front doesn't have as much time to light the unburned mixture out in the squish area thus staving off detonation better than a tall quench or squish band. *_I know I already said it, but I should read the post before I respond. Nothing wrong with committing to memory I guess haha. So the tall quench is leaving unburned fuel that ignites later on top of the clash you previously described AKA bang, bang, damage ensues..._* So a short squish (quench area) can safely & happily run on lower octane fuel but still have higher compression than a tall squish (quench area) build will tolerate. *_This is because the "burn is optimized, so the higher quality fuel is not quite as necessary?_* I hope I worded all that in a comprehensible way. *_You certainly did. I am grateful_* On a brighter note, if the head was cut (poorly), it's now junk so you won't have to worry about it being the problem if it was. 😁 *_Hahahaha Luke at Phathead wants to send me one of his new ones so this will be fun..._* Besides a pressure test, a vacuum test should also be done. A seal can leak one way but not the other. Both are bad. *_I'll have to look that up! The leak down was dropping so fast that I'm still unsure if there's a leak on top of all the other rad engine-party that was going on in there!_* So I'd still confirm the case halves aren't leaking by removing the right side cover by dropping the jug back on with a base gasket (don't even need a piston in it) & try to seal the powervalve area's to confirm the bottom is air tight....or not. *_Did I mention that I should read the post first?? Great idea. The engine will just be that much further taken down already after the wet side seal test concludes._* Don't exceed 7psi on both vacuume & pressuretesting. Anymore & some seals can get the lips flipped &/or get pushed out. *_10-4!_* Your fuel octane is legit & the timing seems NOT to be the culprit judging by the stator being like the other bike which has a known reliable engine. *_I think so on the timing even though it's just the eye-crometer test. I already have the 04 engine dropped back into the blown up 06 chassis so I can test things out with the 06 carb._* Detonation sounds like a bag of marbles getting banged around inside the engine. It has a sort of rattling sound & the engine can only handle it for a very brief time. Like only a couple seconds & junk. Ok awesome (I'm mean, not really) *I am familiar with that sound and the need to add more fuel from Lectrons that needed power jet opened a bit more & some lean-up-top-Keihin's too. My 01 RM250 and the mess it made out of the tail pipe earned me a lot of jetting time in my early 20's... even though the 01 ran sooty even with spot-on jetting. Don't wear white gear & ride behind me back then or I would "pepper" your fresh kit!! I never even heard the rattle on the 06 in this video & the power was very soft already. I guess the last guy got the joy of all the banging gumballs. That would have stopped me dead in my tracks to try and remedy.* Besides a lean main jet, a lean needle setting can cause it as well. *Maybe there's more evidence in the original owner trying to richen the bike up before he sold it or was getting the rattle... The pilot & main were one size larger each, than what I installed. I went with Pro Circuit's specs for all components as they have always been great for me. Sea level, 101 octane, & their main/ pilot/ needle & clip spec were all followed. It was just too late.* I really appreciate the time you took to school me & anyone reading this! -Charles // mXrevival
@@mxrevival Happy to help man. Been the hungry guy trying to learn all & as much as I could. I wish I had a guy around who could've helped me get the right answers back then. So yeah dude, it's cool to help you out. So yes, the head should he parallel to the piston dome or slightly getting larger (1/2 degree) as it gets closer to the dome. With the properly done solder test which is in line with the piston pin, Good numbers & good gains in low-end throttle response are .035"- .042" on a 250cc engine. If it's over .050", I would cut it. From memory, the stocker is somewhere near .070" give or take .010" on that? Typically, after decking the gasket surface (to set the squish/quench height) I dig out the dome to bring the compression back down to stock ratios. Sometimes I go even lower than stock (compression ratios) & they still make more power while being less violent. So a tight squish/quench let's you lower compression & keep your power. The lower compression takes some of that hyper violence away from it but it still pulls with all the muscle it would've had. Just slows down the blitz meter a little...more manageable & let's you be more aggressive for longer & make less mistakes because the bike isn't so violent & blasty. Not a big deal in sand but on dry stuff it's nice. In regards to the "triangle" pocket around the outside of the squish band, detonation happens because that pocket is holding mixture & has a weird sudden spike in pressure around the outside edge of the piston when this ignites which is right above the ring groove area (ring land). This is a weak part of the piston & you know the rest. You want combustion to happen in the dome. The squish is meant to "squish" it all to the dome for combustion.
Like my pro engine builder buddy Jimmy says, "the air needs to come out somewhere" haha! A few very intelligent dudes in the comments also allude to some other potential issues as well. Need to check the center cases where they meet, the cut on the head, etc. Excited to rebuild this soon
Wow that is insane 😳 sorry ya have to go threw all that but one thing about it it great content for the channel and iv for sure learned some thing I never knew today about 2 strokes 😀 that is so nuts. I love the tool great content 👏 👌 👍
yea, the transmission is completely seperate and the only way that the cylinder would leak into the transmission, to leak out of the output shaft would be crank seal.
There are some outstanding replies from JonnoMoto & Keith Peterson In the comments that are more in depth & explain better than I did. I rushed this video, and should have done a better job.
Carnage!!!!! Better it happened now though, had the cheapest setup the owner before you could find.... I agree going oem, expensive but a little piece of mind makes it worth every penny. Good luck bro🤜🏻🤛🏻
I would take the clutch and power valve covers off and retest that right side crank seal as well as the power valve area as mentioned by someone else. Is the power valve sealed from the transmission and clutch cavities? Otherwise they all would have an air leak, right? I've only been into 4 stroke Suzuki, and snowmobile engines without power valves.
It's funny, I was doesn't work at the distance I am from the short-term apartment we're in. The garage is pretty far away and apartment is on the third floor... So I sit one of my cell phones behind it on speaker and then call myself from my other phone also on speaker 😅
No the transmission is not sealed from the PV completey. Johnny Moto nailed it on my oversight. There's a seal on the main shaft that the power valve rides and rotates on, which air could have been pushing through when I pressurized it the cylinder, that would then make its way into the bottom end and out of the counter shaft or sprocket seal. I believe the engine was just damaged already, Maybe because it was already ridden too long or too lean by a previous owner. As far as a retest, at this point we will just rebuild this sucker & I can't wait to ride it again
Gotta do what you gotta do. That's a great idea. I have an engine now. I'm about to do a full rebuild as well. I have split cases and replaced bearings and broken shafts and gears. First time for a full rebuild for me. I'm glad you keep these bad ass videos coming for us. Moving isn't fun or easy.
That is awesome, thank you for letting me know! If it's not too much trouble, and in case I miss your reply here on CZcams, please let me know would you like for it whenever it's convenient for you 🙏 www.mxrevival.com/contact
i think your the only guy that pressure tests a 2 stroke, maybe your crankcase has a leak of somesort, you should just do a full rebuild to save time and heartaches
Happy Saturday Charles !! I bet you are gonna find that you have a crack in one of your crank case covers also...that thing was leaking out fast.I am sorry, but that Baby is due for a total rebuild. I guess that means some more great content is coming my way 🤣
Haha!! Right?? Insanely fast! It will be good practice for me. And in the end much better components inside! You know what's really cool, is I could just snap my '04 engine in here and still enjoy the bike in the meantime
Once the cylinder was machined for a steel sleeve it was ruined, the Nikasil lining dissipates heat much better, that steel sleeve is a recipe for seizing and never ending problems, it's a cheap fix that always ends up being more expensive, the industry spent countless time and money developing that proven technology and some machinist comes along and undoes it just to make a buck bad idea any way you look at it.
Air is getting into the transmission from around the shaft of the main powervalve or the RHS boost port valve when you're pressurising the cylinder.
It's not completely air tight from the crankcase to the powervalve mech which is how it gets oiled from premix. In general operation, compression is made above the powervalve ports and the pressure from combustion would go out the exhaust.
That means there was no air leak as you would have known if the RHS seal was blown. You would have been riding a fog machine with spooge everywhere.
Good luck finding a replacement powervalve, they're rare as hens teeth.
That is super interesting and makes perfect sense now that you've laid it out for me in such a logical manner. Basically right behind the power valve door we've got the cavity where the actuating rod comes up in other words.
I also understand what yourye saying about no spooge. I was wondering how I could have a wet side crank seal leak, but not be burning gobs of transmission oil/ tons of smoke.
This is really cool, thank you for the reply. I'm going to pin it in the comments so other people can hopefully find value in it too.
What would you inspect next as the cause of damage?
The original jetting was fat, each jet one size larger then it should have been for the exhaust combo at sea level.
Although I suppose the last owner who mentioned that it didn't feel quite right may have been trying to feed it more fuel to combat the lean condition, but it was already damaged thus rendering that re-jet pointless.
So if there was no leak, and there was already damage, it was more of a common wear-out & failure?
Thanks for running a clinic JM!
@@mxrevivalno worries. I've been trying to keep my 06 rm250 alive for the last 8 or so years so know it in and out.
When you showed that piston top with the broken ring land my first thought was "somebody got the ring gap wrong".
I remember you had a nightmare trying to get it started which made me wonder if the timing was too advanced in that video. Did you get any indication of pinging when riding?
Right now I think improper assembly was the culprit as it's hard to assess that piston considering the damage. Under the piston crown with a heavy burnt oil patch can be a sign of getting too hot/lean.
@@mxrevival I guess age could be a reason. For some reason I had in mind the PO had recently rebuilt it. I would have expected shattered skirts though
That’s gnarly! Pretty rad to see how that pressure test tool works too!
Pretty fun & quick to build! Thanks Gin 🔥 Going to snap my 04 engine in & keep riding 🤣
2 full wraps, no more than 3,with tape in the direction of tightening, you can add pipe dope on top if u want, it acts as a lubricant to help get the joint tight.
You had 5 wraps?????? I'm a generator technician I install gas lines everyday and I've never had a leak with my joints. That tape had to be garbage, definitely use a pipe dope like blue monster or something to help seal it. 5 wraps is absurd
Always a great breakdown of what you're doing! Excited to follow this one 😎
Thank you bro! And thank you for the goggles, they arrived today 😍
totally nice and helpful content!! you won a new subscriber!!!
Really appreciate your viewership and we promised to keep getting better
You’re going to have to inspect the cases really well to make sure there’s no cracks or warpage unless you know for sure it was leaking from the right side crank seal. I would try to verify that before spending time and money rebuilding. Still waiting for the CR500 rebuild…
Totally agree! It could even be something like a nick between the case halves from the cases being split with a screwdriver! I did think it was interesting that it was coming out from behind the sprocket, then realized this Suzuki doesn't have a crankcase breather like the Yamaha. So the air has to come out somewhere.
Ooooffff. That was an expensive day at the track, in 40 years riding mx I've never done the pressure test but now I'm on older bikes it's essential. Great how-to video👌
🤣 you are right and I definitely made it worse! I appreciate you taking the time to watch
Sweet vid thanks👍👍. Never seen that leak down test done before
Thanks Chris!
I like your shtick man! Making money whilst teaching how to spin spanners properly. Keep going bro, world needs more of it!
Thanks G! I am literally building the live I'd like to live... The money part, well that'll come eventually 🙌 I will never stop! Thanks for the killer comment -Charles // mXrevival
Loving your channel mate. So good to watch and informative. Keep up the good work. From the uk.
I appreciate you dude!
You can be leaking from the center case gasket or the right side crank seal. Gotta pull your right side engine cover to confirm it is/is not NOT the seal.
The powervalve seal on the side of the jug cam let air into the transmission as well. So the case gasket & seals could all be fine but it's leaking fromt the powervalve seal area.
But thay piston is broken. Not blown up. That was detonation that broke the ringland off. The detonation pushed the edge of the piston down under combustion, (pinching the ring). On the way back down, the rings snagged on a port getting bent up & breaking the edge of the piston off. Then as it went to TDC, the broken parts & ring chunks got smashed into the head.
What was your fuel grade?
Where was the timing in comparison to the "stock" setting?
What was the quench height? A bad head cut will cause detonation.
What was the scenario when it died?
But that was detonation 💯% man.
Edit:
Ditch the rad valve for the STOCK cage & reed petals & instal a reed spacer. You'll have more power & better power. Lots of experience & dyno time building engines. Had an 06 rm250 as a personal bike in the stable for a number of years. It's one of my favorite bikes....all time.
*_Keith, I LOVE this reply. It's too bad I can only pin one comment at a time! In response to your questions:_*
You can be leaking from the center case gasket or the right side crank seal. Gotta pull your right side engine cover to confirm it is/is not NOT the seal. *_Understood, and makes more sense at JonnoMoto said that I likely don't have a leak. No excessive smoke trans oil coming out of the pipe. I was somewhat stumped on that in the video._*
The powervalve seal on the side of the jug cam let air into the transmission as well. So the case gasket & seals could all be fine but it's leaking fromt the powervalve seal area. *_Jonno mentioned this too. it makes perfect sense. The air has to come out somewhere in the end so the countershaft seal it is... This threw me off as I also thought maybe a breech between cases but same scenario as the right side crank seal IF it was actually leaking. Jonno suggesting there was no leak makes the most sense now. Funny how I forced the video to that conclusion just because I was hell bent on the leak down tester proving something. I did not do a very good job on this video & should not have rushed things to wrap up._*
But thay piston is broken. Not blown up. That was detonation that broke the ringland off. The detonation pushed the edge of the piston down under combustion, (pinching the ring). On the way back down, the rings snagged on a port getting bent up & breaking the edge of the piston off. Then as it went to TDC, the broken parts & ring chunks got smashed into the head. *_Regarding the lingo (blown up) may I ask the difference when speaking technically? I was using the term blown-up very generically as it could be searched & SEO optimized, or basically understood by most that "there's a problem" of some sort going on here 😂 Thank you for the detonation explanation, I can visualize it all occurring step by step & that is helpful for me._ *
*_Before I answer these, it almost seems safe to say that most of the damage was already done here as I only logged about 45 minutes on the bike in a few short motos. It was the first time I ever rode it. The bike felt lean or soft, like when a main jet is too small and engine wants more fuel to reach higher RMPs._*
What was your fuel grade?
*_101 @ 40:1 always_*
Where was the timing in comparison to the "stock" setting?
*_Unsure, but the stator plate is in the identical location/ orientation as my healthy 04 engine when looking at both side by side._*
What was the quench height? A bad head cut will cause detonation.
*_Unfamiliar with the term & eagerly awaiting more info! Did you ever see "Short Circuit" where the robot Johnny 5 is always begging for "input"?? Call me Johnny!!_*
What was the scenario when it died?
*_It ran until it sort of shut off as I rolled up to the truck. I got off the track because I felt the power degrade to a un-useable level & had to keep it alive by blipping the throttle liberally. The soft power it had before that VS the "tale your arms off" RM power I expected makes it seem like I simply finished off a coffin that was almost fully nailed shut._*
But that was detonation 💯% man.
Edit:
Ditch the rad valve for the STOCK cage & reed petals & instal a reed spacer. You'll have more power & better power. Lots of experience & dyno time building engines. Had an 06 rm250 as a personal bike in the stable for a number of years. It's one of my favorite bikes....all time. *_Ok! I will have to track down an OEM & try it sometime. I have the Vforce & Boyesen as they came with both RM's when purchased. Me too bro, I adore these old RM's which to me don't really feel old yet_*
@@mxrevival
I totally remember that movie short circuit & Johnny 5's hunger for input! I wish I could read like Johnny 5! Lol
So for the input, there are 2 parts of the head. There's the dome area which is the deep pocket around the sparkplug. Then there's the shallow area around the outside of the dome. This is the "squish band" area. It is measured in 2 ways. 1 is the length of the squish band. This is simply a measurement from the edge of the dome, across the squishband to the cylinder wall or outside diameter of the head. The 2nd measurement, called the "quench" area, is a height measurement & its done from the outside of the "squish band" area of the head to the outside edge of the piston at Top Dead Center. It's the gap between the piston & the squishband area of the head when the piston is at TDC.
Measure this with a piece of solder & make sure you do it IN LINE with the piston pin or the sides of the piston by the transfer ports. The reason is to avoid piston "rock" that happens it the measurement is done on the intake or exhaust side of the piston. This would give a false measurement & also give a potentially false notion of the head being cut at a poor angle vs the angle on the crown/dome of the piston. You want to match the angle of the piston dome with the squishband area of the head or have the head about 1/2 a degree steeper than the piston angle.
Bad scenarios would be if the squishband cut in the head is flatter than the piston dome shape. Think of a flat top head design with a dome piston. This will make a triangle pocket around the outside of the piston which will undoubtedly cause detonation. This is the worst.
The measurement for "quench" is that distance between the piston & the squishband. A tall squish, which these bikes (& most) have, is actually a bad thing for detonation. The tall area takes longer for the flame front to reach out to the edges of the cylinder. This tall & slower moving flame front area allows heat (from it) to radiate forward & light off the fuel around the outside edge in the squish band. Now that fuel is burning inward toward the dome & the burning fuel from the done is burning outward. These two fronts collide around the outside of the piston & in the squish area. This excessive pressure happens over the ringland area which smashes the piston edge down on the ring, pinching the ring. The ring no longer floats & can now snag a port on its way past. This happens on its way down from TDC & folds both the ring & piston up breaking off the edge of the piston & tearing up the ring. Then on the way back up, the ring tears up the jug & all of the debris gets smashed into the head. The few extra revolutions the engine makes (from momentum) after the catastrophe are to just make sure it's good & junk. Lol
Anyway, a tight quench is way better for staving off detonation. The shorter flame front heading from the dome to the outside of the cylinder is moving faster & has a shorter heat gradient (less tall which means less surface area to throw heat). This faster moving flame front doesn't have as much time to light the unburned mixture out in the squish area thus staving off detonation better than a tall quench or squishband.
So a short squish (quench area) can safely & happily run on lower octane fuel but still have higher compression than a tall squish (quench area) build will tolerate.
I hope I worded all that in a comprehensible way.
On a brighter note, if the head was cut (poorly), it's now junk so you won't have to worry about it being the problem if it was. 😁
Besides a pressure test, a vacuum test should also be done. A seal can leak one way but not the other. Both are bad.
So I'd still confirm the case halves aren't leaking by removing the right side cover by dropping the jug back on with a base gasket (don't even need a piston in it) & try to seal the powervalve area's to confirm the bottom is air tight....or not.
Don't exceed 7psi on both vacuume & pressuretesting. Anymore & some seals can get the lips flipped &/or get pushed out.
Your fuel octane is legit & the timing seems NOT to be the culprit judging by the stator being like the other bike which has a known reliable engine.
Detonation sounds like a bag of marbles getting banged around inside the engine. It has a sort of rattling sound & the engine can only handle it for a very brief time. Like only a couple seconds & junk.
Besides a lean main jet, a lean needle setting can cause it as well.
I totally remember that movie short circuit & Johnny 5's hunger for input! I wish I could read like Johnny 5! Lol
*_Hahahaha, "Steee-pha-neeee" no dissasemble..._*
So for the input, there are 2 parts of the head. There's the dome area which is the deep pocket around the sparkplug. Then there's the shallow area around the outside of the dome. This is the "squish band" area. It is measured in 2 ways. 1 is the length of the squish band. This is simply a measurement from the edge of the dome, across the squishband to the cylinder wall or outside diameter of the head. The 2nd measurement, called the "quench" area, is a height measurement & its done from the outside of the "squish band" area of the head to the outside edge of the piston at Top Dead Center. It's the gap between the piston & the squishband area of the head when the piston is at TDC.
*_Ok awesome, I have always wanted to try the hollow-core solder trick to check squish but have not yet, and always ran what I had when doing top ends. Sounds like I'd be able to figure out if this head has been cut or modified in doing this too, if I knew what the stock squish was from a confirmed stock head. I'd love to know the limitations & have been doing some homework to become a better educator down the road._*
Measure this with a piece of solder & make sure you do it IN LINE with the piston pin or the sides of the piston by the transfer ports. The reason is to avoid piston "rock" that happens it the measurement is done on the intake or exhaust side of the piston. This would give a false measurement & also give a potentially false notion of the head being cut at a poor angle vs the angle on the crown/dome of the piston. You want to match the angle of the piston dome with the squishband area of the head or have the head about 1/2 a degree steeper than the piston angle. *I should read the entire post before I reply 😂*
Bad scenarios would be if the squishband cut in the head is flatter than the piston dome shape. Think of a flat top head design with a dome piston. This will make a triangle pocket around the outside of the piston which will undoubtedly cause detonation. This is the worst. *_Ahh, I see. So the squish band should follow the curvature (or not) of the intended piston for said engine. They are parallel to each other in easy terms, or for lack of a more technical way for me to explain it? Why does it cause detonation? (thank you)_*
The measurement for "quench" is that distance between the piston & the squishband. A tall squish, which these bikes (& most) have, is actually a bad thing for detonation. The tall area takes longer for the flame front to reach out to the edges of the cylinder. This tall & slower moving flame front area allows heat (from it) to radiate forward & light off the fuel around the outside edge in the squish band. Now that fuel is burning inward toward the dome & the burning fuel from the done is burning outward. These two fronts collide around the outside of the piston & in the squish area. This excessive pressure happens over the ringland area which smashes the piston edge down on the ring, pinching the ring. The ring no longer floats & can now snag a port on its way past. This happens on its way down from TDC & folds both the ring & piston up breaking off the edge of the piston & tearing up the ring. Then on the way back up, the ring tears up the jug & all of the debris gets smashed into the head. The few extra revolutions the engine makes (from momentum) after the catastrophe are to just make sure it's good & junk. *_Lol Well isn't that just dandy?? Good explanation of what I have seen the result of now!! 😂 I understand! So it sounds like modifying the stock head for a tighter squish clearance or purchasing an aftermarket head (which must be why these are made) is how to correct the issue, not taking into account a cylinder base gasket height but in general a remedy to the problem?_*
Anyway, a tight quench is way better for staving off detonation. The shorter flame front heading from the dome to the outside of the cylinder is moving faster & has a shorter heat gradient (less tall which means less surface area to throw heat). This faster moving flame front doesn't have as much time to light the unburned mixture out in the squish area thus staving off detonation better than a tall quench or squish band. *_I know I already said it, but I should read the post before I respond. Nothing wrong with committing to memory I guess haha. So the tall quench is leaving unburned fuel that ignites later on top of the clash you previously described AKA bang, bang, damage ensues..._*
So a short squish (quench area) can safely & happily run on lower octane fuel but still have higher compression than a tall squish (quench area) build will tolerate. *_This is because the "burn is optimized, so the higher quality fuel is not quite as necessary?_*
I hope I worded all that in a comprehensible way. *_You certainly did. I am grateful_*
On a brighter note, if the head was cut (poorly), it's now junk so you won't have to worry about it being the problem if it was. 😁 *_Hahahaha Luke at Phathead wants to send me one of his new ones so this will be fun..._*
Besides a pressure test, a vacuum test should also be done. A seal can leak one way but not the other. Both are bad. *_I'll have to look that up! The leak down was dropping so fast that I'm still unsure if there's a leak on top of all the other rad engine-party that was going on in there!_*
So I'd still confirm the case halves aren't leaking by removing the right side cover by dropping the jug back on with a base gasket (don't even need a piston in it) & try to seal the powervalve area's to confirm the bottom is air tight....or not. *_Did I mention that I should read the post first?? Great idea. The engine will just be that much further taken down already after the wet side seal test concludes._*
Don't exceed 7psi on both vacuume & pressuretesting. Anymore & some seals can get the lips flipped &/or get pushed out. *_10-4!_*
Your fuel octane is legit & the timing seems NOT to be the culprit judging by the stator being like the other bike which has a known reliable engine. *_I think so on the timing even though it's just the eye-crometer test. I already have the 04 engine dropped back into the blown up 06 chassis so I can test things out with the 06 carb._*
Detonation sounds like a bag of marbles getting banged around inside the engine. It has a sort of rattling sound & the engine can only handle it for a very brief time. Like only a couple seconds & junk. Ok awesome (I'm mean, not really) *I am familiar with that sound and the need to add more fuel from Lectrons that needed power jet opened a bit more & some lean-up-top-Keihin's too. My 01 RM250 and the mess it made out of the tail pipe earned me a lot of jetting time in my early 20's... even though the 01 ran sooty even with spot-on jetting. Don't wear white gear & ride behind me back then or I would "pepper" your fresh kit!! I never even heard the rattle on the 06 in this video & the power was very soft already. I guess the last guy got the joy of all the banging gumballs. That would have stopped me dead in my tracks to try and remedy.*
Besides a lean main jet, a lean needle setting can cause it as well. *Maybe there's more evidence in the original owner trying to richen the bike up before he sold it or was getting the rattle... The pilot & main were one size larger each, than what I installed. I went with Pro Circuit's specs for all components as they have always been great for me. Sea level, 101 octane, & their main/ pilot/ needle & clip spec were all followed. It was just too late.*
I really appreciate the time you took to school me & anyone reading this!
-Charles // mXrevival
@@mxrevival
Happy to help man. Been the hungry guy trying to learn all & as much as I could. I wish I had a guy around who could've helped me get the right answers back then. So yeah dude, it's cool to help you out.
So yes, the head should he parallel to the piston dome or slightly getting larger (1/2 degree) as it gets closer to the dome.
With the properly done solder test which is in line with the piston pin, Good numbers & good gains in low-end throttle response are .035"- .042" on a 250cc engine. If it's over .050", I would cut it. From memory, the stocker is somewhere near .070" give or take .010" on that?
Typically, after decking the gasket surface (to set the squish/quench height) I dig out the dome to bring the compression back down to stock ratios. Sometimes I go even lower than stock (compression ratios) & they still make more power while being less violent. So a tight squish/quench let's you lower compression & keep your power. The lower compression takes some of that hyper violence away from it but it still pulls with all the muscle it would've had. Just slows down the blitz meter a little...more manageable & let's you be more aggressive for longer & make less mistakes because the bike isn't so violent & blasty. Not a big deal in sand but on dry stuff it's nice.
In regards to the "triangle" pocket around the outside of the squish band, detonation happens because that pocket is holding mixture & has a weird sudden spike in pressure around the outside edge of the piston when this ignites which is right above the ring groove area (ring land). This is a weak part of the piston & you know the rest. You want combustion to happen in the dome. The squish is meant to "squish" it all to the dome for combustion.
Wow quite a roundabout right side crank leak hahaha. It's gonna make a few awesome videos though!
Like my pro engine builder buddy Jimmy says, "the air needs to come out somewhere" haha! A few very intelligent dudes in the comments also allude to some other potential issues as well. Need to check the center cases where they meet, the cut on the head, etc. Excited to rebuild this soon
Great vid Charles, I really enjoyed it. Thanks for sharing and take good care.
Thanks dude!
Wow that is insane 😳 sorry ya have to go threw all that but one thing about it it great content for the channel and iv for sure learned some thing I never knew today about 2 strokes 😀 that is so nuts. I love the tool great content 👏 👌 👍
Thanks my brotha!
I guess I’m confused how a crankcase leak would get into the cylinder. Wouldn’t you have a leak between the transmission area and crankcase also?
yea, the transmission is completely seperate and the only way that the cylinder would leak into the transmission, to leak out of the output shaft would be crank seal.
Air being pumped in is getting into the transmission via the powervalve shaft or RHS boost port powervalve mech.
There are some outstanding replies from JonnoMoto & Keith Peterson In the comments that are more in depth & explain better than I did. I rushed this video, and should have done a better job.
Carnage!!!!! Better it happened now though, had the cheapest setup the owner before you could find.... I agree going oem, expensive but a little piece of mind makes it worth every penny. Good luck bro🤜🏻🤛🏻
Haha!! YES! I totally agree on the oem. Hard to argue with hundreds of thousands of dollars of Japanese R&D right??
Dude, those video baby monitors are the shit. Only way I'm getting out to the shop when mama's working.
I would take the clutch and power valve covers off and retest that right side crank seal as well as the power valve area as mentioned by someone else. Is the power valve sealed from the transmission and clutch cavities? Otherwise they all would have an air leak, right? I've only been into 4 stroke Suzuki, and snowmobile engines without power valves.
Those old Suzuki 2 stokes in old Arctic Cats are bulletproof!
It's funny, I was doesn't work at the distance I am from the short-term apartment we're in. The garage is pretty far away and apartment is on the third floor... So I sit one of my cell phones behind it on speaker and then call myself from my other phone also on speaker 😅
No the transmission is not sealed from the PV completey. Johnny Moto nailed it on my oversight.
There's a seal on the main shaft that the power valve rides and rotates on, which air could have been pushing through when I pressurized it the cylinder, that would then make its way into the bottom end and out of the counter shaft or sprocket seal.
I believe the engine was just damaged already, Maybe because it was already ridden too long or too lean by a previous owner.
As far as a retest, at this point we will just rebuild this sucker & I can't wait to ride it again
Gotta do what you gotta do. That's a great idea. I have an engine now. I'm about to do a full rebuild as well. I have split cases and replaced bearings and broken shafts and gears. First time for a full rebuild for me. I'm glad you keep these bad ass videos coming for us. Moving isn't fun or easy.
furnco cap for the yz's
Go pro x rod and piston 😎👍🏼👏🏽
Absolutely!!
I have a crank for an 04 rm 250, it would need a rebuild but if i remember its a stock crank
That is awesome, thank you for letting me know! If it's not too much trouble, and in case I miss your reply here on CZcams, please let me know would you like for it whenever it's convenient for you 🙏 www.mxrevival.com/contact
i think your the only guy that pressure tests a 2 stroke, maybe your crankcase has a leak of somesort, you should just do a full rebuild to save time and heartaches
Oh dude, absolutely. Needs full rebuild with OEM parts or equivalent. 🙌 thanks for watching!
Happy Saturday Charles !! I bet you are gonna find that you have a crack in one of your crank case covers also...that thing was leaking out fast.I am sorry, but that Baby is due for a total rebuild. I guess that means some more great content is coming my way 🤣
Haha!! Right?? Insanely fast! It will be good practice for me. And in the end much better components inside! You know what's really cool, is I could just snap my '04 engine in here and still enjoy the bike in the meantime
Hell yeah dude🔥🤙🤘
💪💪💪💪
Time to build a stroker 295 monster 450 killer!
Definitely have to look into the big bore situation right now, why not?
@@mxrevival absolutely!!!! Hole shot all those 4 strokers
Good morning!
Likewise!!
What a Saturday charelles has a blown bike
Me I have a sprained ankle due to mud
Smash the👍
Ahh dang dude, heal up fast!!!
What do you mean running tight?
It's an expression used to express the engine feeling sort of bound up / something is wrong or not running right.
Once the cylinder was machined for a steel sleeve it was ruined, the Nikasil lining dissipates heat much better, that steel sleeve is a recipe for seizing and never ending problems, it's a cheap fix that always ends up being more expensive, the industry spent countless time and money developing that proven technology and some machinist comes along and undoes it just to make a buck bad idea any way you look at it.
I'm not a fan either!!
lol you said full cockroach mode!
🤣 man I am hurtin' a little bit away from my regular shop/ tools!!! #FullCockroachMode
@@mxrevival i built a airplane in a garage smaller than that love the show get the RM screaming again.
Too funny, just like the trailer shop! I was like "damn it this 1 car garage is bigger than my shop!" 😂
Them smokers always blowing up
🤣🤣🤣
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