79CC Rear Sprocket Help!

[BaraaBikes]

So Built a OCC Chopper using a Predaotr 79cc with a exhaust and a air filter, no other mods to the engine, My rear wheel is 20" and I have a 10t clutch. I dont want to waste money on a Transmission and getting a torque converter would cost me alot and would still have problems. I tried using a 44t rear sprocket and it didnt work out to well for me (bad takeoff and 35ish top speed) The ratio is so bad that im not even hitting speeds where the governor is slowing me down, any sprocket suggestions? I was thinking about getting either a 54t or a 60t. (I dont want to get the transmission)

 

[5-7HEAVEN]

What’s a transmission, in your words?

If you don’t want one, get the biggest rear sprocket that’ll fit.

 

[Chainlube]

35 mph on a governed 80 cc is pretty good. If you go with a bigger wheel sprocket your take off will be better but your top end will suffer. You might be able to get 30 out of a 60t but then the governor will kick in and slow you down.

 

[BaraaBikes]

What’s a transmission, in your words?

If you don’t want one, get the biggest rear sprocket that’ll fit.

The 79cc transmission that you can get from gas bike or some homemade jack shaft system that is complicated is what I consider a “transmission”. I want to get a big sprocket but I don’t want it to be “too big” (too much torque no high end)

 

[BaraaBikes]

35 mph on a governed 80 cc is pretty good. If you go with a bigger wheel sprocket your take off will be better but your top end will suffer. You might be able to get 30 out of a 60t but then the governor will kick in and slow you down.

I want to be able to hit 45-50 with a reasonable amount of torque, and I’m definitely thinking of modding up the the engine (19mm carb, governor removal, porting) are the only mods I’m thinking of doing. So should I get the 60t or 54t?

 

[Chainlube]

Hold off on the new gear until you are done your mods, if you want to go 50 you better add some stiffer valve springs. They will float around the 5000 rpm mark. Are you running the motor gear right on the crank or a centrifugal clutch? I think you'll be faster with a 44t or 36t than a bigger gear.

 

[5-7HEAVEN]

You’re asking a lot, for what you have now.

Get the 54t.

After your mods, see how that works.

Sometimes, it’s trial and error.

 

[gary55]

I want to be able to hit 45-50 with a reasonable amount of torque, and I’m definitely thinking of modding up the the engine (19mm carb, governor removal, porting) are the only mods I’m thinking of doing. So should I get the 60t or 54t?

I'm afraid it's one or the other with a single speed sprocket setup and the engine you're using. For both you need a jack shaft setup to a shifter hub. With the occ I'm not sure what the bike will allow. You would need at least135mm dropouts for the internal hub. Sikk bike parts might have some info if the j shaft setup is possible on a occ? Else wise 5-7 is probably right on the 54t. If the engine doesn't have enough power to hit the gov. with the 44 a 48 or 54 might have at least the same top getting to the gov with better low end. As long as the chain stays run parallel you should be okay with sprocket/chain clearance to the stay. If the stays converge in toward the front it can restrict the size sprocket you can use.
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[Chainlube]

I'm afraid it's one or the other with a single speed sprocket setup and the engine you're using. For both you need a jack shaft setup to a shifter hub. With the occ I'm not sure what the bike will allow. You would need at least135mm dropouts for the internal hub. Sikk bike parts might have some info if the j shaft setup is possible on a occ? Else wise 5-7 is probably right on the 54t. If the engine doesn't have enough power to hit the gov. with the 44 a 48 or 54 might have at least the same top getting to the gov with better low end. As long as the chain stays run parallel you should be okay with sprocket/chain clearance to the stay. If the stays converge in toward the front it can restrict the size sprocket you can use.
View media item 62630
View media item 62629
View media item 62417

Do you remember where you got those wheels in your #1 and #2 pictures? I need a couple 24" for my next bike, I have a couple 17" M/C wheels that once the rubber gets put on will be close to 24". I just want the wheels to be a little lighter than those.

 

[gary55]

Do you remember where you got those wheels in your #1 and #2 pictures? I need a couple 24" for my next bike, I have a couple 17" M/C wheels that once the rubber gets put on will be close to 24". I just want the wheels to be a little lighter than those.

purple bike #1 has 26" rims but are sun rhino lites sim to these. Green bike 24" rims came with the donner bike for the build Fito Modena then laced 5 speed hub with new spokes. Amazon.com : SUNringle Sun Rhyno Lite 24" 36 Holes Black Rim w/Silver Sides, Schrader Valve : Bike Rims : Sports & Outdoors