Another helpful video Jason, I just bought a project 1973 DT3 250 imported to UK all the way from Minnesota. This video helped me find the fault and get her started before I began the strip down 👍🏻
My 73 DT250 been sitting up for 15 years but going to try to get it running again. It ran pretty good when I first got it in 2002 but then hesitation issues and would stop. Will pull it out and get it running again I hope.
I was able to experiment rewiring a stator and check the voltage as the bike was running. This was not an easy task it actually took me 3-4 times rewiring to get this correct. So when I was finished I had 9 volts to the coil at high rpm, this seemed to be the number the xr75 needed to run correctly without sputtering at higher rpm. This is a 6v system. Hope this helps someone.
Yes, I did, but sadly for most, my issue was that the source coil was from a later model year. The coil bolts in, but the windings are different. I converted to 12v and haven't looked back.
@@robertparks7657 I'm sorry for the late reply on this... I'm sure it's too late to help you, but I'll still answer it to help future viewers w/ the same question. On a stock 1974 DT, there is no "12v coil". In the video above, there are two coils that are visible... the one on the left is the "source coil", which provides spark for the ignition system. The one on the right side is the lighting coil, which in the case of the DT, produces 6V AC. (In reality, it produces less than that at idle and more than that at redlilne, but at mid-RPMs, it's in that ballpark.) A tiny portion of that AC is rectified into DC power to charge the 6V battery and run items such as the horn and tail light. Why don't they run it ALL from AC? Because laws required that even if the bike died at night time, the tail light would be visible. Thus the 6v DC battery and rectification from AC to DC. Why not run it ALL on DC instead of a mashup of AC and DC parts? Cost. It costs money to rectify watts from AC to DC. The more watts you want to convert, the more expensive the rectifier is. So the bean counters at Yamaha won the battle of cost by going with the tiniest rectifier possible for the items that required DC, then ran the rest directly from the AC magneto. In fact, in many of the early DT models there isn't even a REGULATOR. The output of the magneto perfectly matched the current draw of all lights in the system. Of course, this meant that if you, say, blew a headlight (which drew a lot of the current), then all of the other lights in the system would be OVERpowered and blow out shortly thereafter!
no...when they are saying primary coil...they mean the primary side of your spark plug coil...not the source coil of the stator...thats why it is 1.9 ohms or what ever they have for specs ..no way your source coil is under 2 ohms...it be in the hundreds ..thats why they also have the secondary coil reading...thats the secondary side of the spark plug coil...the lead plug wire..you got a bad source coil still probably and that reading spec is not up on your screen and its much higher reading
Thank you, and you're absolutely correct! That primary coil value from the service manual had NOTHING to do with the source coil I was testing in this video. The primary coil and the source coil are two entirely different components that I had confused. Thanks for this correction.
Hi Sean, great video. My 71 DT250 lost spark mid-ride and I'm stumped. Resistance across my secondary coil is within spec but I have zero resistance across my primary coil. How is this possible, what does this mean? Nothing can make a person feel incompetent like electrical issues.
Hi jason i got a 72 dt250 mines has 2 black wire coming out of the magneto one to the coil and the other one is lose do you know were the other black wire lead to
Hi! I have xt500. 6v From mag get out 3 wires 2 black .2 yellow The blue ground is joined to the frame beyond the chaine Doesn't sparking before disapprarance spark from brigh became yellow.voltage is in the circuit but appear weak. Outpuy v variable between 4 and 6 . could be the coil or mag that might lost magnetism.thank
That’s a good point. I can’t recall if my capacitor was in or out for this video. In the end, my issue was that the entire stator was the wrong one for the year of my bike. No amount of adjusting or testing would fix that. 😀
@@1607rosie correct, I didn’t mean to imply that it wasn’t. I simply meant that I had already checked off all the “easy” boxes, such as replacing it. I just couldn’t remember if it was in or out at the time of shooting this video. For some troubleshooting steps, it’s better to have that out of the system (example: measuring coil resistance)
Hi, is it normal that the ignition source coil is shortend to the ground plate when all 3 cables soldered to condenser ? I have no spark when flywheel is installed. I believe it's not normal that the cable from the ignition source coil is shortend to ground or is it normal ?
Yes, it's correct for one side of the source coil to ground to the frame. Then when the flywheel rotates around that coil, it's generating current. That current WANTS to find a way back to the frame to complete the circuit. If the key is on, then the only path to do that should be through the spark plug. But if the wire coming out of the other end of the source coil has a ground ANYWHERE else in the system, your spark plug wont' fire. This is what the key/kill switch does... it grounds that wire. But to answer your original question, yes, one end of the ignition source coil absolutely grounds to the frame.
thanks for you quick answer. ok, you say the cable coming from the source coil grounds to the frame. when the source coil is not connected to the condenser, I have a connection from the source coil cable to the ground but If I solder all three cables (blue from breaker, b/w from ? and brown from source coil to the condenser my spark plug won't fire. what is the easiest way to find the bad ground ?
@@fredheimer Are you saying if you unhook the condenser, you get spark? That makes it sound like you have a bad condenser or a sloppy solder joint that's grounding it somewhere. I would suggest reading this post (and other posts like it on this forum) and if it doesn't help you answer your question, post a new question... there are guys on that forum that know these bikes much better than me! yamaha-enduros.com/index.php/forums/74-76-twin-shock/1668-dt-250-electrics-doing-my-head-in?start=0
Yes, my replacement was the PowerDynamo 12v conversion from here: hvccycle.net/yamaha-dt-rt-dt250-dt360-dt400-cdi-ignition-12v-180w-7238799dc/ But keep in mind that, while I LOVE the conversion and the magneto is bolt-on, there are some wiring challenges you'll need to face. If you're looking to stick with your 6v Yamaha magneto but it has issues, I would HIGHLY recommend contacting a user named DEET from a vintage Yamaha enduro forum: yamaha-enduros.com/index.php/my-own-profile/993-1971dt1e DEET rebuilt the magneto on the DT250 in this video... the problem, however, was that this magneto was not FOR the bike in this video. That is, DEET did an amazing job on the rebuild (it literally came back looking brand new), but in the end, it was for a 1978 DT, not my 1974. Hope this helps!
Hey so If those coils on the right side of the stator are just for lights, then would a break in one of those lighting coil windings make it not spark. Like can it still be installed and not working and make spark or is the an actual way you have to delete or bypass the lighting coil? Sorry, total newb.
That is the correct setup. 2-strokes can foul plugs pretty easily if they’re too rich, so Yamaha did this so that you could just move the coil wire from the fouled plug to the “spare”, then still make it home.
what do you think it would be if it was working just fine but once you hit like 4th gear and up it would start dying out and now it has no spark coming from the plug..?
Dying out in 4th gear sure sounds like an issue I had which turned out to be a float set to the incorrect level. But that would be completely unrelated to your no-spark condition.
I have a 1973 DT250, and I can't find a diagram on how the stator plate is wired with everything. Would you be able to take a picture of yours for me just so I can see how everything is wired?? I'd really appreciate it!
I could take a picture, but I'm afraid it might not give you much information. Can you tell me more information about what you specifically need to know? Are you re-winding the lighting and/or source coils? If so, then the source coil is EASY... one end of the windings gets grounded, and the other end goes to the black wire in your harness. If it's the lighting coil, it's a bit different. ROUGHLY halfway through the windings of the coil, they offshoot the green/white wire. Because it only has roughly half of the winds, it produces less energy and is used in the "daytime" mode (no headlight). The windings continue on the lighting coil and run into the green/red wire, which feeds the "nighttime" mode, which has enough extra energy to power the headlight. But again, I'm not sure what you're ultimately trying to accomplish or troubleshoot. Any detail you could provide would help.
I appreciate your response! I actually ended up getting mine running after all. The source coil appeared to be wired backwards, and someone put a "new" ignition coil which actually ended up being faulty. Put the original ignition coil in it and then found out the person before me put the carb together backwards, aka the little throttle cylinder was in backwards so the throttle was stuck on... after that scary disaster my bike idles so sweet I didn't even have to time it, I bought it for 300$ 3 years ago and couldn't figure out how to make it run so it just sat in my backyard and I'm so happy I finally got it running. Now I have a new issue however, and I'm assuming its a tuning issue? Basically the bike fires right up on choke and idles and revs in neutral, but as soon as it turn choke off it dies or taking off with with the choke still on. I went through the carb and cleaned it all out so its super clean so it has to be a tuning issue i'm assuming.
Glad it's running! That's a positive first step. When you say it needs the choke to run, think logically about what that means from the engine's perspective. The purpose of the choke is to give the engine a richer fuel:air ratio when the engine is cold. SOME carbs (such as those commonly found on lawnmowers and chainsaws) do this by restricting the airflow to the engine. Less air=richer mixture. The DT250 carb, as is common in motorcycle carbs, works by introducing additional fuel to the engine. When you use the choke on the DT, you're unplugging a jet circuit that pours more fuel into the engine. So if it only runs right when you have the choke on, this tells you that one of two things is happening. 1) You have a clogged jet/circuit somewhere in your carb (not getting enough fuel to the engine), OR 2) You're getting too much air to the engine. Do you need to use the choke ONLY for low RPM use (meaning that it runs great at mid/wide open throttle)? Or is it anemic even when wide open? If you only need the choke for low RPM stuff, this is the classic symptom of a clogged pilot jet. The pilot jet gives it fuel at low RPMs. When it's blocked, the choke kind of "fakes" the fuel provided by the pilot jet. I have another video on CZcams for the carb on this bike. Check it out and see if your pilot jet looks as clean as mine. It has radial and lateral holes, so make sure they're ALL open. If you need the choke to run at ALL RPMs, then I bet you have an air leak. These are SUPER common on older two strokes like our DTs. The crankcase of a 2-stroke goes through pressure and vacuum cycles that a 4 stroke engine doesn't do. The crankshaft seals on both the clutch and magneto side are notorious for leaking when they age. You need to do a leakdown test to see if your engine holds both vacuum and positive pressure. I could/should create a video on this process, but there are plenty of guides online on how to do this. When I did my leakdown test, I found that my engine was incredibly leaky... it wouldn't hold vacuum for more than 10 seconds. I feared that I was going to have to split the cases, but when I sprayed the engine down with soapy water and put positive pressure in the crankcase, I found that my leak was simply where the 2T oil line hooked to the engine! It was literally just a missing copper gasket. When I replaced that, the engine was remarkably tight and leak free! The leakdown test on a 2T engine really is mandatory. A minor air leak will give you tuning headaches as long as you own the bike. A bigger air leak will give you a lean condition that can toast your engine entirely. It's a BIT of work to create the leakdown setup (but can be done inexpensively using Harbor Freight tools and auto-parts exhaust parts). But it's a part of owning a proper running 2-stroke. Do it! Good luck!
Jason Scott what do you mean by 2T oil line exactly? I don't believe mine has a oil pump or anything like that, and yeah it just stalls the bike as soon as I turn the choke off regardless of the rpm, do you do the leak down test with through the carb or with it off? Also, this might be a leak but I'm not sure, does your throttle linkage have a o ring on it going into the hat of the carb? Mine doesn't it just kind of floats on top of the brass adjuster thing, I wonder if that's where the air leak could be. I'll definitely do a leak down test on it this weekend just to test everything I appreciate the info!! I don't think the seals are bad as they look to be replaced.
patrickpl94 the 2T oil line goes from the right side of the engine case to the cylinder. All DTs have it, unless someone converted it to premix-only. There is no o ring on the throttle cable. A leak test is done with the carb and exhaust OFF, but the spark plug in (and cylinder at or near TDC).
I have the same bike with 8,000 miles and then sat a fews years started for about an hour but wasn't working right either in 4th or 5th gear it just wouldn't pick up anymore then after awhile the bike just stopped working I have no clue what it is I changed the top coil but the bottom ones I don't know anything about so I'm stuck
For troubleshooting help, you're better off going to a forum such as yamaha-enduros.com. Am I correct to assume that you have no spark? If so, it's best to unplug the black wire off the secondary coil (the one under the tank) that goes to your key and kill switch. I had an intermittent spark issue that was completely stumping me one time, and it was traced to a key switch that kept momentarily grounding out (and cutting spark in the process).
Jason Scott I actually went through the whole bike last night haha nd found out there was oil where the magneto goes so I cleaned it all out nd tried it again nd now it's 100% sparking so I just gotta get a new carb cuz my floats were getting stuck then it should be running nd I'll prolly run mixed gas instead of the automatic one it has so it don't overflow again thanks tho very much ;)
Glad it's working, but I would question what you're proposing to do. Your oil autolube system and your carb are 100% separate systems. They don't interact with each other at all. So you say you had oil in the magneto, but that your carb float stuck. Those are unrelated issues. And if, indeed, you have a carb float issue, pre-mixing gas/oil will not fix anything. If it was purely an oil leak (and not gas), pre-mixing would also not fix it. If you truly see oil in your magneto, then it's nearly guaranteed that you have a bad magneto crankshaft seal. Your crankcase becomes pressurized on every revolution of the crank, and if that seal leaks, then oil will blow past it. I would HIGHLY recommend you do a leakdown test on your bike. I predict that you'll find 1 or more leaky seals, and if you have leaky seals, getting it to run right is going to be an exercise in futility. Google how to do a leak down test on a 2 stroke motor and give it a shot. It's not too terribly hard, and I came up with my own leakdown test equipment using parts from the auto parts store and a Harbor Freight vacuum gauge. Good luck!
Jason Scott yeah I know there serperate it's just my carb was stuck so I'd rather but a new one I was just saying I'm gonna run the mixed gas instead but I tried it after and there was no oil coming out without the cover so it should be perfect the top and bottom end was redone
@@Musalini-oq7bu I can't give tips based on no symptoms, but start a post at the site above and there are a number of experts who can help out. Step 1 will be to give the basics about the bike and what you've already tried. Have you checked for spark? Cleaned the carb? Checked compression? Stuff like that. Good luck!
Another helpful video Jason, I just bought a project 1973 DT3 250 imported to UK all the way from Minnesota. This video helped me find the fault and get her started before I began the strip down 👍🏻
My 73 DT250 been sitting up for 15 years but going to try to get it running again. It ran pretty good when I first got it in 2002 but then hesitation issues and would stop. Will pull it out and get it running again I hope.
Thanks for the video .
I was able to experiment rewiring a stator and check the voltage as the bike was running. This was not an easy task it actually took me 3-4 times rewiring to get this correct. So when I was finished I had 9 volts to the coil at high rpm, this seemed to be the number the xr75 needed to run correctly without sputtering at higher rpm. This is a 6v system. Hope this helps someone.
Yes, I did, but sadly for most, my issue was that the source coil was from a later model year. The coil bolts in, but the windings are different. I converted to 12v and haven't looked back.
did you do the rex spped shop conversion?
I bought the PowerDynamo kit. Not sure if it's what you linked to or not. All I know is that it works great!
Jason Scott where can we locate the 12 volt coil? Thanks, Bob
Question Jason I have the same bike as you and bought the same kit. What ignition timing mm did you set your bike at. Thanks
@@robertparks7657 I'm sorry for the late reply on this... I'm sure it's too late to help you, but I'll still answer it to help future viewers w/ the same question. On a stock 1974 DT, there is no "12v coil". In the video above, there are two coils that are visible... the one on the left is the "source coil", which provides spark for the ignition system. The one on the right side is the lighting coil, which in the case of the DT, produces 6V AC. (In reality, it produces less than that at idle and more than that at redlilne, but at mid-RPMs, it's in that ballpark.) A tiny portion of that AC is rectified into DC power to charge the 6V battery and run items such as the horn and tail light. Why don't they run it ALL from AC? Because laws required that even if the bike died at night time, the tail light would be visible. Thus the 6v DC battery and rectification from AC to DC. Why not run it ALL on DC instead of a mashup of AC and DC parts? Cost. It costs money to rectify watts from AC to DC. The more watts you want to convert, the more expensive the rectifier is. So the bean counters at Yamaha won the battle of cost by going with the tiniest rectifier possible for the items that required DC, then ran the rest directly from the AC magneto. In fact, in many of the early DT models there isn't even a REGULATOR. The output of the magneto perfectly matched the current draw of all lights in the system. Of course, this meant that if you, say, blew a headlight (which drew a lot of the current), then all of the other lights in the system would be OVERpowered and blow out shortly thereafter!
nice video jason. i have a 74 ty 250 losing spark after you ride long enough to get it warm
no...when they are saying primary coil...they mean the primary side of your spark plug coil...not the source coil of the stator...thats why it is 1.9 ohms or what ever they have for specs ..no way your source
coil is under 2 ohms...it be in the hundreds
..thats why they also have the secondary coil reading...thats the secondary side of the spark plug coil...the lead plug wire..you got a bad source coil still probably and that reading spec is not up on your screen and its much higher reading
Thank you, and you're absolutely correct! That primary coil value from the service manual had NOTHING to do with the source coil I was testing in this video. The primary coil and the source coil are two entirely different components that I had confused. Thanks for this correction.
@@hermetheuscoffee Jason, I have a 1977 dt250. Any chance you want to sell your magneto.
I think I need one.
@@will7its I don’t have this bike anymore unfortunately.
@@hermetheuscoffee Ok, thank you
My source coil is reading 1.5 ohms. What should it be reading? If you know please.
1977 DT250 Thanks
Hi Sean, great video. My 71 DT250 lost spark mid-ride and I'm stumped. Resistance across my secondary coil is within spec but I have zero resistance across my primary coil. How is this possible, what does this mean? Nothing can make a person feel incompetent like electrical issues.
Hey Jason, what threads are the flywheel puller? I ordered the Motion Pro 27mm X 1.0 LH but it’s not threading into my 1974 dt250a.
Hi jason i got a 72 dt250 mines has 2 black wire coming out of the magneto one to the coil and the other one is lose do you know were the other black wire lead to
Hi! I have xt500. 6v
From mag get out 3 wires 2 black .2 yellow
The blue ground is joined to the frame beyond the chaine
Doesn't sparking before disapprarance spark from brigh became yellow.voltage is in the circuit but appear weak. Outpuy v variable between 4 and 6 . could be the coil or mag that might lost magnetism.thank
I don’t really do motorcycle troubleshooting in CZcams comments, but Yamaha-enduros.com is an excellent website to find help from other owners.
Don't forget to check your condenser. a bad condenser will make it run bad .or not at all. I'm not sure how far out you can be in your resistance.
That’s a good point. I can’t recall if my capacitor was in or out for this video. In the end, my issue was that the entire stator was the wrong one for the year of my bike. No amount of adjusting or testing would fix that. 😀
Jason Scott I grew up with that type of ignition on cars and motorcycles. The capacitor is a vital part of your ignition.
@@1607rosie correct, I didn’t mean to imply that it wasn’t. I simply meant that I had already checked off all the “easy” boxes, such as replacing it. I just couldn’t remember if it was in or out at the time of shooting this video. For some troubleshooting steps, it’s better to have that out of the system (example: measuring coil resistance)
Good job.
Thanks!
Hi, is it normal that the ignition source coil is shortend to the ground plate when all 3 cables soldered to condenser ? I have no spark when flywheel is installed. I believe it's not normal that the cable from the ignition source coil is shortend to ground or is it normal ?
Yes, it's correct for one side of the source coil to ground to the frame. Then when the flywheel rotates around that coil, it's generating current. That current WANTS to find a way back to the frame to complete the circuit. If the key is on, then the only path to do that should be through the spark plug. But if the wire coming out of the other end of the source coil has a ground ANYWHERE else in the system, your spark plug wont' fire. This is what the key/kill switch does... it grounds that wire. But to answer your original question, yes, one end of the ignition source coil absolutely grounds to the frame.
thanks for you quick answer. ok, you say the cable coming from the source coil grounds to the frame. when the source coil is not connected to the condenser, I have a connection from the source coil cable to the ground but If I solder all three cables (blue from breaker, b/w from ? and brown from source coil to the condenser my spark plug won't fire. what is the easiest way to find the bad ground ?
@@fredheimer Are you saying if you unhook the condenser, you get spark? That makes it sound like you have a bad condenser or a sloppy solder joint that's grounding it somewhere. I would suggest reading this post (and other posts like it on this forum) and if it doesn't help you answer your question, post a new question... there are guys on that forum that know these bikes much better than me! yamaha-enduros.com/index.php/forums/74-76-twin-shock/1668-dt-250-electrics-doing-my-head-in?start=0
did you ever get to the bottom of it? i have a 68 DT1 with weak spark/no start
Yes, the short answer is that the magneto in this video is for a 1978 DT, not a 1974! I was chasing my tail the entire time.
Hey Jason. I have a 75 DT250, and am having trouble finding a replacement magneto. Can you let me know where you got yours? Thanks in advance!
Yes, my replacement was the PowerDynamo 12v conversion from here: hvccycle.net/yamaha-dt-rt-dt250-dt360-dt400-cdi-ignition-12v-180w-7238799dc/
But keep in mind that, while I LOVE the conversion and the magneto is bolt-on, there are some wiring challenges you'll need to face. If you're looking to stick with your 6v Yamaha magneto but it has issues, I would HIGHLY recommend contacting a user named DEET from a vintage Yamaha enduro forum: yamaha-enduros.com/index.php/my-own-profile/993-1971dt1e
DEET rebuilt the magneto on the DT250 in this video... the problem, however, was that this magneto was not FOR the bike in this video. That is, DEET did an amazing job on the rebuild (it literally came back looking brand new), but in the end, it was for a 1978 DT, not my 1974. Hope this helps!
@@hermetheuscoffee I see. So the magneto in the video was for the wrong bike, and you replaced it with the one from the link above correct?
Joshua Poling that is correct!
Hey so If those coils on the right side of the stator are just for lights, then would a break in one of those lighting coil windings make it not spark. Like can it still be installed and not working and make spark or is the an actual way you have to delete or bypass the lighting coil? Sorry, total newb.
Sorry for the late reply. You can consider these two independent systems. You don't need the lighting coil at all to fire the spark plug!
I have a 76 and it has one coil wire but 2 spark plugs? Is that not supposed to be like that?
That is the correct setup. 2-strokes can foul plugs pretty easily if they’re too rich, so Yamaha did this so that you could just move the coil wire from the fouled plug to the “spare”, then still make it home.
what do you think it would be if it was working just fine but once you hit like 4th gear and up it would start dying out and now it has no spark coming from the plug..?
Dying out in 4th gear sure sounds like an issue I had which turned out to be a float set to the incorrect level. But that would be completely unrelated to your no-spark condition.
Jason Scott never seen you answered but the carb I redid my self nd that was perfect I just can't get the spark 😴
I have a 1973 DT250, and I can't find a diagram on how the stator plate is wired with everything. Would you be able to take a picture of yours for me just so I can see how everything is wired?? I'd really appreciate it!
I could take a picture, but I'm afraid it might not give you much information. Can you tell me more information about what you specifically need to know? Are you re-winding the lighting and/or source coils? If so, then the source coil is EASY... one end of the windings gets grounded, and the other end goes to the black wire in your harness. If it's the lighting coil, it's a bit different. ROUGHLY halfway through the windings of the coil, they offshoot the green/white wire. Because it only has roughly half of the winds, it produces less energy and is used in the "daytime" mode (no headlight). The windings continue on the lighting coil and run into the green/red wire, which feeds the "nighttime" mode, which has enough extra energy to power the headlight.
But again, I'm not sure what you're ultimately trying to accomplish or troubleshoot. Any detail you could provide would help.
I appreciate your response! I actually ended up getting mine running after all. The source coil appeared to be wired backwards, and someone put a "new" ignition coil which actually ended up being faulty. Put the original ignition coil in it and then found out the person before me put the carb together backwards, aka the little throttle cylinder was in backwards so the throttle was stuck on... after that scary disaster my bike idles so sweet I didn't even have to time it, I bought it for 300$ 3 years ago and couldn't figure out how to make it run so it just sat in my backyard and I'm so happy I finally got it running. Now I have a new issue however, and I'm assuming its a tuning issue? Basically the bike fires right up on choke and idles and revs in neutral, but as soon as it turn choke off it dies or taking off with with the choke still on. I went through the carb and cleaned it all out so its super clean so it has to be a tuning issue i'm assuming.
Glad it's running! That's a positive first step. When you say it needs the choke to run, think logically about what that means from the engine's perspective. The purpose of the choke is to give the engine a richer fuel:air ratio when the engine is cold. SOME carbs (such as those commonly found on lawnmowers and chainsaws) do this by restricting the airflow to the engine. Less air=richer mixture. The DT250 carb, as is common in motorcycle carbs, works by introducing additional fuel to the engine. When you use the choke on the DT, you're unplugging a jet circuit that pours more fuel into the engine. So if it only runs right when you have the choke on, this tells you that one of two things is happening. 1) You have a clogged jet/circuit somewhere in your carb (not getting enough fuel to the engine), OR 2) You're getting too much air to the engine.
Do you need to use the choke ONLY for low RPM use (meaning that it runs great at mid/wide open throttle)? Or is it anemic even when wide open?
If you only need the choke for low RPM stuff, this is the classic symptom of a clogged pilot jet. The pilot jet gives it fuel at low RPMs. When it's blocked, the choke kind of "fakes" the fuel provided by the pilot jet. I have another video on CZcams for the carb on this bike. Check it out and see if your pilot jet looks as clean as mine. It has radial and lateral holes, so make sure they're ALL open.
If you need the choke to run at ALL RPMs, then I bet you have an air leak. These are SUPER common on older two strokes like our DTs. The crankcase of a 2-stroke goes through pressure and vacuum cycles that a 4 stroke engine doesn't do. The crankshaft seals on both the clutch and magneto side are notorious for leaking when they age. You need to do a leakdown test to see if your engine holds both vacuum and positive pressure. I could/should create a video on this process, but there are plenty of guides online on how to do this.
When I did my leakdown test, I found that my engine was incredibly leaky... it wouldn't hold vacuum for more than 10 seconds. I feared that I was going to have to split the cases, but when I sprayed the engine down with soapy water and put positive pressure in the crankcase, I found that my leak was simply where the 2T oil line hooked to the engine! It was literally just a missing copper gasket. When I replaced that, the engine was remarkably tight and leak free!
The leakdown test on a 2T engine really is mandatory. A minor air leak will give you tuning headaches as long as you own the bike. A bigger air leak will give you a lean condition that can toast your engine entirely. It's a BIT of work to create the leakdown setup (but can be done inexpensively using Harbor Freight tools and auto-parts exhaust parts). But it's a part of owning a proper running 2-stroke. Do it! Good luck!
Jason Scott what do you mean by 2T oil line exactly? I don't believe mine has a oil pump or anything like that, and yeah it just stalls the bike as soon as I turn the choke off regardless of the rpm, do you do the leak down test with through the carb or with it off? Also, this might be a leak but I'm not sure, does your throttle linkage have a o ring on it going into the hat of the carb? Mine doesn't it just kind of floats on top of the brass adjuster thing, I wonder if that's where the air leak could be. I'll definitely do a leak down test on it this weekend just to test everything I appreciate the info!! I don't think the seals are bad as they look to be replaced.
patrickpl94 the 2T oil line goes from the right side of the engine case to the cylinder. All DTs have it, unless someone converted it to premix-only. There is no o ring on the throttle cable. A leak test is done with the carb and exhaust OFF, but the spark plug in (and cylinder at or near TDC).
I have the same bike with 8,000 miles and then sat a fews years started for about an hour but wasn't working right either in 4th or 5th gear it just wouldn't pick up anymore then after awhile the bike just stopped working I have no clue what it is I changed the top coil but the bottom ones I don't know anything about so I'm stuck
For troubleshooting help, you're better off going to a forum such as yamaha-enduros.com. Am I correct to assume that you have no spark? If so, it's best to unplug the black wire off the secondary coil (the one under the tank) that goes to your key and kill switch. I had an intermittent spark issue that was completely stumping me one time, and it was traced to a key switch that kept momentarily grounding out (and cutting spark in the process).
Jason Scott I actually went through the whole bike last night haha nd found out there was oil where the magneto goes so I cleaned it all out nd tried it again nd now it's 100% sparking so I just gotta get a new carb cuz my floats were getting stuck then it should be running nd I'll prolly run mixed gas instead of the automatic one it has so it don't overflow again thanks tho very much ;)
Glad it's working, but I would question what you're proposing to do. Your oil autolube system and your carb are 100% separate systems. They don't interact with each other at all. So you say you had oil in the magneto, but that your carb float stuck. Those are unrelated issues. And if, indeed, you have a carb float issue, pre-mixing gas/oil will not fix anything. If it was purely an oil leak (and not gas), pre-mixing would also not fix it. If you truly see oil in your magneto, then it's nearly guaranteed that you have a bad magneto crankshaft seal. Your crankcase becomes pressurized on every revolution of the crank, and if that seal leaks, then oil will blow past it. I would HIGHLY recommend you do a leakdown test on your bike. I predict that you'll find 1 or more leaky seals, and if you have leaky seals, getting it to run right is going to be an exercise in futility. Google how to do a leak down test on a 2 stroke motor and give it a shot. It's not too terribly hard, and I came up with my own leakdown test equipment using parts from the auto parts store and a Harbor Freight vacuum gauge. Good luck!
Jason Scott yeah I know there serperate it's just my carb was stuck so I'd rather but a new one I was just saying I'm gonna run the mixed gas instead but I tried it after and there was no oil coming out without the cover so it should be perfect the top and bottom end was redone
If it dose Leak again Ima just have to that thank you tho very much ;)
Temperature...
Can you please recommend websites for this bike
Yes! Yamaha-enduros.com
@@hermetheuscoffee thank a bunch I got one of these bikes 1977
Trying to get it to run again
Any tips ?
@@Musalini-oq7bu I can't give tips based on no symptoms, but start a post at the site above and there are a number of experts who can help out. Step 1 will be to give the basics about the bike and what you've already tried. Have you checked for spark? Cleaned the carb? Checked compression? Stuff like that. Good luck!
@@hermetheuscoffee ok thanks a bunch mate I appreciate the lookout