Gearing for 79cc Lifan

Tang

Member
Sep 29, 2013
72
1
8
Indianapolis
I'm trying to work out maybe a better gear ratio....I have to change Jack shaft out.(bent)..changing from 5/8 to 3/4 inch.....Bike top speed is 24 mph....My weight is 250 lbs....Original gearing is...11t clutch to 36t j/s in....10t j/s out....50t axel...with 16.364 to 1 ratio.....I live in some what hilly area.....Will also do some upgrades (carb, intake, possibly govenor.)
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,397
60
48
Tang, you're really pushing that motor!

With governor, redline at 3600rpm is 17mph.
Right now, @ 24mph, engine's turning almost 5100rpm.
If you just change to 12t j/s, redline @ 20.4mph
At 24mph, engine will spin almost 5100rpm.

Your first priority is to remove the governor.
 

Tang

Member
Sep 29, 2013
72
1
8
Indianapolis
So govenor first, 10t to 12t...what about the 36t J/S in sprocket.
Ok...maybe I'm lost on this. I thought removing govenor will make motor rev and redline even more.
Will the sprocket change the redline on motor. I do want some speed increase. Maybe say 35 mph over all with better torque.
 
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5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,397
60
48
Methinks your gear ratio is way too low(numerically high). I'm sorry. I believe I gave you wrong info.
Coincidentally, I'm planning a 212cc Predator install into a 7-speed comfort bike. I'm trying to run its power thru the multi gears.
With a TC2 geared @ 2.7:1 and 83t/17t timing pulleys and 24t/14t chainring/ cassette, my final drive is 7.69:1. That works out to 36mph @ 3600rpm. If I remove my governor, theoretically, the bike might hit 50mph @ 5000rpm.

So my advice to you is to lower your gear ratio drastically. Search this forum and the other one, to see what gearing other heavy guys with your engine are using.
BTW, I weigh 210lbs.
 
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