How to Port & Polish, Shave Eyebrows: Briggs 5 hp Flathead Performance Mods
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- čas přidán 23. 01. 2016
- Shows how to upgrade your Briggs and Stratton 5 hp flat head engine by porting the intake and exhaust, as well as shaving the eyebrows.
THE BUILD VIDEOS
1) Governor Removal • How to Remove the Gove...
2) Custom intake and Exhaust • BRONDA Engine, Custom ...
3) ReJetted the Carburetor • How to ReJet a Carbure...
4) Tachometer Test • How to Install a Tacho...
5) Mini Bike Build Intro • Mini Bike Build: Baja ...
6) Port and Polish • How to Port & Polish, ...
7) Connecting Rod Install • Arc Billet Connecting ...
8) Piston and Rings • How to Install a Pisto...
9) Billet Flywheel • Arc Billet Aluminum Fl...
10) Camshaft and Valve Train • Camshaft & Valve Train...
11) Head, Plug, and Break- In • Gasket, Plug & Engine ...
12) Mini Bike Race!!! • Mini Bike Race
LINKS TO ALL PARTS I USED IN THE BUILD SERIES
amzn.to/2ikIjx3 7/8" ID 304 stainless steel tubing
amzn.to/2jfdR7f 212cc honda clone carburetor
amzn.to/2jEJH9U stainless steel plate
amzn.to/2ikMqsY emulsion tube, jet, air filter adapter, and air filter
amzn.to/2jrAbaU tachometer
amzn.to/1TCB91P Valve Grinding Compound
amzn.to/1WL9LBG Feeler Gauge
amzn.to/2aHkOJQ Valve Lapping Tool
amzn.to/2b3BcFq Assembly Lube
PPREDATOR 212CC PERFORMANCE PARTS
INTAKE & EXHAUST (hemi & non-hemi versions)
kartfab.com/go-kart-engines-pr...
CAMSHAFT: (hemi -ebay) goo.gl/9MxkXv (non-hemi ebay) goo.gl/90EnIQ
SPRINGS: (ebay) goo.gl/yCtGV1
HONDA GX200/HONDA CLONE/ BOX STOCK PROJECT PERFORMANCE PARTS
INTAKE & EXHAUST Same as Predator 212cc
kartfab.com/go-kart-engines-pr...
CAMSHAFT: (ebay) goo.gl/PZ0bBK
SPRINGS: (ebay) goo.gl/DQk72E
BRIGGS & STRATTON 5 HP FLAT HEAD PERFORMANCE PARTS
goo.gl/bZai2B Billet Flywheel
goo.gl/elbuKh Billet Connecting Rod
Misc Performance parts for 5hp FlatHead (aka raptor3 )found at www.out2win.com/catalog/raptor...
kartfab.com Visit my website for go kart plans, restorations, and maintenance walk throughs
Visit my channel for more go kart videos / kartfab
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KartFab Google+: plus.google.com/+KartFab - Auta a dopravní prostředky
Silly putty or just modeling clay to seal up those ports instead of rags, works like a charm. I like silly putty for its non stick qualities.
Great vid brother.
Hey BBQJOE here. Great videos! You're easy to understand, the lighting is good, and you're relaxed and not nervous. All those things make for good watching, whatever the topic.
Keep up the good work!
+joesbarbecue1 thanks for the kind words!
Good video. You are articulate, concise, but explain very well. I look forward to more of your videos.
I think you made a fine video. Starting out slow and not overdoing the ports is smart. You can't go back. Remember there's people on here that all they want to be is toxic. I owned a custom Harley shop and built lots of engines . Did all my own machine work and I can say you did a fine job of explaining the process.
Good luck.
Looks simple enough. I just sold my go kart yesterday,gonna share the 'eyebrow shave trick with new owner.
When shaving the eyebrows we always shaved into the cylinder being careful to stay above the piston ring
Yes you can, the piston going a little into the valve area never hurt anything
@@connorssmallengines6663 You grind the wall down untill their even or the piston crown is flush: it's called " relieving" the block, in a Sidevalve. Trev New Zealand 🇳🇿🇳🇿
@@trevinskiking2165 But you can safely go down to the top ring witness mark - - is the point. The intake and exhaust gasses will have a large, clean shot.
@@TIMEtoRIDE900 What I said,just abreviated for simplicity....cheers NZ
Don't make the exhaust any bigger. The exhaust port on a flathead Briggs 5hp is too big from the factory. Smoothing out the casting lines is fine.
Dude I polished my 5hp like you did and it ran its ass off thanks and I put a washer on the sparkplug and that made the spark shoot straight to the piston and that made a big difference in performance
Did a pretty good job. I did the almost same thing on my kids 5hp Briggs, I took a little more off in the runners on mine. It really woke up the motor. If wondering, made low end rpm way stronger, but I have a stock cam also. I love cruising down the street and then just hammer on it, LOL.
+prancstaman yeah, it revs pretty good :-)
@@KartFab Ditto ...Trev New Zealand PS only Flatheads are a low end to midrange Engine: look up the Daytona winning Hudson Twin H powered 308ci L6 6cyl Flathead from the 1950s...a built in chopped Merc too , unlike an OHV...many of which thrive on Revs ( for those of us less knowledgeable ) Cheers everyone from NZ...before you say or think it; no I'm not bragging...Cheers
Great job! Thank you
Good job I'm glad you done this one im starting to build a flathead and want to put some good solid horsepower to it bit keep it at a dependable level to. Just want good performance
Scott I can sell you a new 98cc Chinese built Flathead if you want new to work on.Their very reliable & I'm in New Zealand but I possibly could get one dropshipped to you in the states from China, spares are plentyfull if you wanted to go new. PM me if your interested.Trev NZ🇳🇿
How much power do with these modifications?
We have to do the two things or flat head enough?
You can buy carbide cutters for working with metal. For aluminium, get a coarse cutter and use a coating of grease in the port to keep the aluminium from plugging the flutes. As the grease fills with filings, wipe it out and put on another coat. Wash the grease off before using sanding drums. The grease is messy, but makes the job easier and gives a better finish.
One major area to promote flow is the "short-side" radius. On the Briggs, this is right where the roof of the port turns up to the valve. You want to make this a smooth curve with no sharp edges.
The intake should be finished with a coarse sanding drum to give a slight roughness to promote turbulence along the port wall which helps eliminate fuel sticking to the port.
The exhaust should be as smooth as possible to promote flow and minimize carbon buildup.
Unless going for high RPM, making the ports bigger can be detrimental to power, so go for smoothing the port and eliminating sharp edges rather than removing a lot of material.
Not legal for legal 4 limited class folks
i bought one of these for my mini bike and when i took the piston out of the engine the piston was damaged really badly but luckly the cylinder walls can be repaired
Eyebrows looked good, ports not so much. 😬👍
you did a fine job
thanks
you will get almost as good in further gains buy recessing the exhaust valve & radiising the valve seats...radiis the cylinder side of the exhaust channel as well, to about 16th abouve the comp ring & remove the brudge between the valves to encourage exhaust flow scavenging into the intake to promote earlier intake flow if using the std cam...will prote much easier flow from the intake valve & better swirl into the cylinder through the exhaust channel.
Great Channel Man! Not sure if you will ever see this but Epoxy on the Intake 90 Degree Turn would be a good idea and I bet would gain about a good 1/2 HP or so.
yeah, lots of dead space there. Ive also heard that you should thread a pipe into the exhaust and cut it off flush to help speed up the exhaust velocity as it is already way too slow.
I feel like you did a pretty good job.👍
Thank you!
I like what you did, but I would have left much more of that that center ridge untouched, the part between the "eye brows" , kept it a little higher, that actually helps to channel intake gas into the cylinder head. Question, how much HP did you gain ?
You get a small loss in compression and a big flow gain so you can rev higher. I have seen jr dragsters that just have the entire “eyebrow” area milled off for flow with supporting modifications. You are right about the center section though and I even missed a spot where the eyebrows transition into the cylinder. I was going off of the information provided to me by someone I thought was experienced but it was just his personal preference. I got a different block and went back to a thicker head gasket for flow gains and I thing the .050” head gasket helped more with flow than eyebrow shave and thin head gasket.
Good job. I have only 4 engines now. I find it much easier to use the grinding stones attachments. Cone shaped, cyclinder shaped, and frisbee shaped.
I did however grind down my guides to create a much smoother transition. I saw it done it pics online and it didn't have any ill effects on the engine.
I practice a few times on two of the 97 mL engines since they're so cheap.
It helped build my confidence.
Ohh and by practicing on the cheapo engines it allows to get a feel for how much to can knock off the casting of the sidewalls.
+2SlickNick I 'practiced' on my NOS engine, so that's why I didn't port that much out. Also, I read that if you port out too much (esp the exhaust) it kills your velocity (which kills torque) so I just went the safest route.
@@KartFab Yeah : want to keep to around 85% Exh to Intake flow or you can overport or overflow & go slower taking too much off.
Stones for Cast metal, grinding bits for alloy( Stops stones from loading up on Alloy ) Cheers everyone From NZ...World's fastest old Indian Bike ...no I'm not bragging before some Troll says it. Cheers
once i go and get a new steel wool brush tool for my Dremel i will do this mod to all my old Flathead engines
And if i want to shave the exaust's bearing????? How can I do it?
Nice
you were pretty conservative on the porting and polishing. Then again it's been 21 years since I've done this. :)
thanks
looks a good job i ported an old ford 2.0 litre cast head using your same principle..... as long as you dont take too much material off or go too deep to upset flow characteristics you dont need a flow bench(where a specialist tuning company measures the port flow during porting making sure the flow works as if done wrong the engine will lose power at certain rpm?this is what i was advised...but could be wrong?...great video well presented....thanks for sharing
You can grind the tops of the valve guides it's not going to hurt them. Your not removing enough of the guide to affect the valve life.
yep! thanks for the tip.
ive heard that when you grind the inside of a engine block you have to use lube so it dont rust. is that correct
Aluminum doesn’t rust
Would an 8HP briggs engine benefit from porting and polishing, as well as doing the eyebrows?
One word Tom: Yup. Trev New Zealand 🇳🇿
Good video, why don't you want intake chamber smoothed out?
Intake needs to be slightly rough (like sandpaper) to help maintain fuel atomization
Nice work what about shaving the head or get a copper gasket
If you are following the playlist, one of the next videos goes over what head-gasket i put on there, which is about half as thick and is copper.
The last time I shaved my eyebrows my girlfriend left me again.
+Dan Henderson lulz
Lol
i think u did a pretty good job and its funny im acually in the process of doing the exact same thing to and older 5hp briggs myself
and im going to steal your honda carb on briggs engine idea
instead of a bilit fly wheel i am putting a 3hp flywheel of a lawn mower i found that is aluminum and i am taking the points off and converting it to a magneto and making a special bracket to fit the magneto lower and so i cann adjust the degrees of timing
+Dale Jackson cool man! You don't have to steal my idea, i give my ideas out for free so everyone can benefit. Advancing the timing by 3-4 degrees is optimal for a gas engine at lower rpms. 5-7 (maybe 8) is better for the methanol engines.
+Dale Jackson thanks!
@@dalejackson5003 Dale ,a slider motorcycle carb is like night & day compaired to the butterfly type...run one around 22mm & you'll never look back. Trev NZ 🇳🇿
built a 3.5hp when I was a kid and did all that and more man that go-kart was so fast but I want to make one for my kid like the video.
Porting is specifically useful at higher RPM. During high RPM the gases have less time to enter and exit the cylinder so better flow is critical. Porting does not help so much during mid to low RPMs.
Nice Video!
John Fraser
Cleaning up and staying mild helps all over.
I had something my dad ported for me when I was a kid, haha a moped.
it had the same power in the basement maybe a little more responsive,but the midrange woke up dramatically and the top end was tons better.
It depends on how crazy you go but yea huge ports aren't known for nice low end power.
The cleanup , with a fresh top end increased top speed from 29 to 37 lol
It would be great to measure pressure just below the intake valve as a function of rpm, with and without porting. I'm going to guess that there are gains to be had at low rpm too.
You did good on removing the eye brows but that port and polish looked rough.
I'd love to see some dyno numbers on a stock flatty and then with each mod done. I've seen some vids but they never seem to show the numbers for a bone stock b.f.h.5. we all know it's not 5hp.
True that! There was actually an extensive write up on that. I forget where it’s posted, multiple message boards. Might have to do some searching “5 hp Briggs modification guide”
i got a 3ho push mower that needs tweeked
would be interesting to hear if there is any way to identify a kart engine or any other small engines, i'm working on a small engine that had no indication as to the make and model but it looks exactly like the one from the video with the exception of the intake and exhaust ports being swapped, so being able to identify a small engine would be rather helpful in my case >.
+TriniRogue Tecumseh engines typically have intake and exhaust reversed
2 years late but Maybe a hs50 or h50?
Why is it so important to leave the intake side rough? Or at least not polished? I honestly need to know im building my first limited motor and everything into consideration
Keeps fuel atomized.
Question. On these Kool Bore blocks is there enough material there to re-sleeve with a cast iron sleeve?
+Racer X I'm not sure, but I have heard of it being done. One thing to watch out for is the crank. If the side cover and block don't have beings in them for the crank, it's not worth doing any upgrading.
KartFab Thanks. The side cover does but the flywheel side does not. I can get a sleeve for under 40 bucks but have to call and see what the machining cost will be. Might be cheaper to start with a new block.
@@Shaft-Industries Ask your machinist:simple Trev NZ🇳🇿
Did you say make sure its not super smooth???...
im gonna do this to my old Blown up Briggs 5 hp once i get the cylinder walls fixed
im also going to do this to all my other Flathead engines i have like 5 Flathead engines
Would this work on a Tecumseh H60?
RoughRoad Garage why not
I work with them all day, I'm a small engine mechanic. I would never actually own or use one, haha!
I got one. Dual ball bearing block with cast iron bore. Put in brass valve guides and a few other goodies. It’s fun just to have not the one in this video.
can you also make mini bike frame plans ?
+Jochen Decaestecker Probably not this year. This year I am doing drift trike plans. You can get an azuza mini bike kit and build it up.
exhaust should be "D' Shape , flat inner elbow bend.greater or same crosssetional area,
Can you grind the threads out of the exhaust port
The exhaust port is actually too big. What a lot of people do is thread in some pipe which increases exhaust velocity
How many powerhorses did this put into the engine?
No idea. I dont even know what a powerhorse is.
where can i get parts for a briggs raptor?
+Gahl Yogu out2win
do you know a good website to buy go karts from
+Jrgaming ebay, bmikarts, gopowersports, ombwarehouse, gokartsusa, and craigslist (my favorite).
Great video grant im gonna port and polish my first small engine (briggs flathead) please feel free to follow the build and offer advice .. thanks for great content
Good luck buddy! Pay attention to the inside short turn radius on the intake and exhaust. That's the part you need to focus on the most. Cutting eyebrows arent really necessary, just focus on smoothing out the sharp edges rather than cutting out material from the combustion chamber. Also, a part not shown in the video is the transition from the eyebrow to the combustion chamber, you can and should cut that into a smooth transition but dont go into the ring land.
@@KartFab Agreed. Trev NZ🇳🇿
plz do the other video i just got my hands on a 1980's briggs 5hp out box never ran and i want to mod the shit out it
+Joseph DePew check out my progress on instagram - KartFab Im almost done modding it. One thing you should do before you decide to mod it, is check to see if it has a cast iron sleeve, or is a "cool bore" aluminum bore. You also need to see if it has bearings on the crank.
What size billet piston rods you use for your 5hp was probably
+Crazyjesse11 standard length
And what is stander length for a 5hp ?
the "castings" or "burrs" you talked about are called flashing, just so you know.
+Poptart McJelly thanks.
I need your help and advice
With?
How did you get your engine so clean?
wire wheel
+KartFab thank you i really appreciate it
After porting .. find a 4hp head. Small cc chamber .. bump up the comp.
i heard that too, but very restrictive flow with the smaller head.
I love your videos and I think their awesome but could you try to be more thorough. sometimes I end up a little confused. thanks
In fact the exhaust isn't where the gain is at all, it's more in the intake, it's still a bit rough normally you want to decrease the angle of attack, that's what I Dit with a Honda engine (gx) and fill the port with some filler stuff. But I am gonna try this in my own briggs. Good video by the way
Shaving the eyebrows is only good for the top end. I wouldn't recommend doing it unless you have supporting mods.
Could you apply the same theory to other engines?
Porting, yes. Shaving eyebrows is specific to the flathead. Most engines are OHV and much more efficient.
***** thanks!
@@KartFab Shaving a Flatheads "eyebrows" is called relieving. Trev New Zealand🇳🇿
supersmooth is too smooth..
Where have u gone ?
+Eisa Furniturewala dont worry, i am posting a video tonight
Can I just tattoo my eyebrows instead of Shaving them and get more power?
will this work for a tecumseh?
Depends on if its a flathead tecumseh or ohv. OHV is not the same and doesnt suffer from the flow problems of the flathead (L-head) engine.
KartFab well for the flat heads of course
Yep. Just dont take too much off. Check the compression ratio too. The briggs flathead engine already has a crappy compresison ratio, so it isnt hurt much by doing this to unlock flow for higher rpms.
i have a engine that as no compression so it wont run but everything is rebuilt so what could it be
+rcmaster 1965elcamino explain 'everything is rebuilt'
+KartFab the piston,rings,seals,carb rebuilt,new head gasket,new bearing, new valves and new springs.
did you do it yourself or did you have someone do it for you? Were the valves lapped and valve lash set?
+KartFab I did it and the valves is lapped and lash set. this is my 20th engine rebuild I did but this one don't work.
with the spark plug, can you rotate the crank to the compression stroke by hand and then it bounces back, or does it rotate right on through? Did you double check the camshaft gear dot lines up with the dot on the crank? new headgasket? head bolts torqued to spec? Id check out all that stuff first, but if in reality you did a complete thorough rebuild, the problem may be in the piston/rings/bore itself.
The eyerow job looked ok but the porting you could have gone alot more streamlined. The short turn radius on these is just terrible and needs amuch rounded and easier turn and in the bowl needs a ramp on the back side rather than a cut out cup, I realize that this will require aluminum to be added but it will help in the airflow. just stick your finger in it and any sharp turns or areas where its just a dead area by your finger will need to be filled in, Just keep in mind the straighter the better.
can you do a retro race kart build?
I have a modern go kart I'll be fixing up.
Alright do you still have the oval track kart ?
Yea
R.I.P my old Briggs 5 hp the old owner of the engine ran it without oil and it overheated the piston a couple of pieces of metal off the piston got melted onto the cylinder walls might take it to a machine shop someday and have the cylinder walls repaired
im gonna see if a machine shop can fix the cylinder if they can then im going to put the Flathead on a mini chopper project im working on
You’ve got two options if you take it to a machine shop. 1) bore oversize and put in new piston. 2) put in a cast iron sleeve. And have it bored to whatever size.
The inside walls of both the intake port and exhaust port needs to be pulled back to more inline with the entrance to the intake seat & pulled inline with the exit from the exhaust seat. What was shown in the video won't help at all. Lol
Where did u get this engine
+dylan harrigan eBay nib bare block with crank
did u buy it of someone or a company
and do you still have this engine ive been looking for one for a while and cant finde one
+dylan harrigan yeah I still have it. You can get a used Briggs racing engine or something else too
would you consider selling it? ive been looking for a while
actually im not sure if you want to make it "super smooth" , advised by professional engine tuners you should have some texture ... theres a scientific explanation but im not 100% on the details so i dont want to confuse.
+Gahl Yogu you are right. Exhaust can be polished but intake should be a little but rough to help keep the fuel atomized.
good to know thanks!
Apparently helps increase "swirl" - making the burn more efficient.
Lots of comments from experts on port & polishing. Wonder how many ever operated a flow bench to see whats happening and actually seen the results on a dyno from their work? My guess is they are just regurgitating what they seen on other amateur vids or weby backyard forums.
+Mazda rx7 yup. I am trying to find a place in Dallas Fort Worth TX to get this on a dyno, but nothing yet :-(
Without a dyno, make one change, test and record. But testing conditions should be as close as possible each time. results will vary under different atmospheric conditions. Or look around for plans and make a dyno
But even with a dyno you still have to make one change/mod for each run or you don't know what did what. Comes down to cost of change to improvement.
Got an extra 4-5k? I'll get a dyno for that.
The combustion chamber modification was very good however the porting was a joke...
How I got here I don't know. I'm needing yo thin out my eye brows, they look like caterpillars over my eyes.
If your old enough & knowledgeable enough you'll know it's called Ported & for the area between the valves & piston - that's called: relieving or for a Flathead as Jan & Dean sung
"She's ported & relieved & she's stroked & bored" Trev New Zealand🇳🇿Use the correct terminology.
Those words are actually from the Beach Boys' song "Little Duece Coupe" . "She's ported and relieved and she's stroked and bored. She'll do 140 in the top end floored. She's my little duece coupe. You don't know what I got. Little duece coupe you don't know I got""
Your technical description of the process is correct however.
Just cause it sounds good, don't mean it is... You need angles for turbulence... Which mixes the fuel for a better burn..
I think it is a great video but you can just get buy the new Predator Ghost engine instead of spending hundreds of $$ on billet parts and get a small boost.
Yes and OHV engine is better than Flathead for the most part
Flat head Briggs looks more enjoyable. Thankfully my old man has plenty of old Briggs 3.5s and 5s in his shed to play with.
wouldn't Briggs do this if they thought it would help?
+mkosak00 Briggs made this engine for Industrial equipment to run at 3600 rpm. If you are running it at that rpm, none of this is necessary.
It's a mass-produced engine. They want to spend as little as possible to manufacture an engine that "gets the job done" and charge as much as possible for the product.
Its easy juat steal one
the intake should never be smooth so the air/fuel can mix a lot better :)
+Boss Kelso Ummm.... 'No'. Fuel/air are mixed in the carburetor... what he is port/polishing is the passage inwhich the said mixture will be traveling into the cylinder. A textured surface is a 'restriction' for said flow (envision a stone path vs a sidewalk, and your feet are the drag on the momentum down the path/passage).
If enough is ported/routed from the intake side (w/out taking out too much metal, ofcourse), 'that' and possibly adjusting the jetting up (a size, if needed), can increase HP/torque abit more (.5~1hp)... not counting the free flow intake and header he's already probably added 2hp from stock. ;-)
+Tihm Kart if the intake is polished and smooth, then the gas may form droplets on it, and atomize worse!
The problem with doing many mods at the same time is you have no idea what actually gave you how much improvement. Your only going by what the manufacturer says, which is often BS
not a horrible job for a first motor. Could be a little better if you bought the right bits for the job. lol
The only way your going to see improvements from your work is with a flowbench and ccing the chamber with a burrete with liquid? That is the proper way to build a motor and also degree the cam with a degree wheel! Lot of work for a motor of this size you bet but just going off of videos your shooting in the dark and chasing your tale! Get a good performance book and speak with vendors and always trust your own work with solid numbers and procedures? Never although informative base your work on u tube videos! Sound working knowledge and procedures puts you in the winners circle!
+Mike Mansfield Can you please buy me a flow bench and dyno? I don't currently have an rn tea 5-10 grand just laying around
Throw the flat head in the trash can, buy a briggs animal, make double the power and torque.
predator factory racing eats briggs animals for lunch bahahaha. I actually modified that flathead some more and its pretty mean. Never as good as OHV will be, but its fun to have.
BOOOORIIIING.
Do better
Why bother with a piece of shit like a Briggs? Just get a Honda.
I got 6 Honda’s haha. Why mess with a briggs? Because I can.
Very nasally voice I mean it's good but very boogered up
It’s a curse really.