Thinking of modding my 79cc

Will'smotobikes19

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While my 79cc motor is on the bench I think I will modify it. It already has a better plug so I'll probably get a bigger main jet, remove governor, make the exhaust into a straight pipe and was even thinking of taking the stock valve springs from the 212 hemi and putting them in the 79cc. Upon further inspection not only was my coil going but one of the rockers was way too loose. I think I will try to limit rpm with the throttle stop and maybe get a tachometer. I could try to drill the jet but I don't know what the stock size is or what it should be drilled to. I like how the motor looked on the Micargi with the same name- predator. Also mountain bike handlebars on a stretched beach cruiser aren't comfortable I found out. Any tips or info appreciated also what top speed would I be getting in the 40's? I couldn't get the clutch off so I bought a puller. The clutch is shot I think when you spin it it hangs up and it slipped before so might have to get another one.
 


JerboaJohn

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it's normal OHV? long as you have it on the bench, clean up the casting esp. exhaust side. if you leave the governor in, you can file n polish either the arm or top of the shaft 1-1.5mm for an extra 4-500rpm.
 

JerboaJohn

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is this a long-term build or just a short project? yaknow, you can sleeve the PTO shaft to fit a 3/4" 3Dmotorsport clutch hahaha.
look up secret tuning tips small engine (various wordings) and see what ya can apply to single cyl. 80cc theoretically can do 4-5hp on a stock cam
 

Will'smotobikes19

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86013


So I took the gov out. Looked inside and these little 79's actually have a cast iron bore! not your flathead briggs lawnmower from the 90's. I wonder how many miles these things can go. Probably more than a CG for the same price $100. They are bigger but they have torque and better lubrication. The spring on the right is a stock hemi 212 spring and the left is stock 79cc spring. The 79 spring actually looks thicker but it's shorter. I was thinking of using a tachometer and the existing throttle stop to gain rpm but not over rev. This thing isn't even broken in yet. Ran it last spring for a few months before the coil went and the clutch was crap. It looked right on the bike so I will put er back on. It was very sluggish with the governor because of slipping and it wasn't fully engaging. Does anyone know any good 5/8 clutches possibly even not chinese.
 
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mark20

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Sep 26, 2018
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View attachment 86013

So I took the gov out. Looked inside and these little 79's actually have a cast iron bore! not your flathead briggs lawnmower from the 90's. I wonder how many miles these things can go. Probably more than a CG for the same price $100. They are bigger but they have torque and better lubrication. The spring on the right is a stock hemi 212 spring and the left is stock 79cc spring. The 79 spring actually looks thicker but it's shorter. I was thinking of using a tachometer and the existing throttle stop to gain rpm but not over rev. This thing isn't even broken in yet. Ran it last spring for a few months before the coil went and the clutch was crap. It looked right on the bike so I will put er back on. It was very sluggish with the governor because of slipping and it wasn't fully engaging. Does anyone know any good 5/8 clutches possibly even not chinese.
max torque SS is a good clutch, i havent tried hillard but ive heafrd good things about them, i would keep it stock and get one that engages at 2200-2800 rpm, that will make that thing move!
 

Will'smotobikes19

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Oh the gov is destroyed now lol. I could actually just sit on the bike with max throttle and it wouldn’t move. Always had to pedal. Tapped the hole too.
 
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