Gearbox Ratio

[Nova1971]

Does anyone know the gearbox trans ratio on these new Chinese belt drive
equipped kits? Is it 4:1 or 5:1? No info in the descriptions of these
4 stroke kits. I believe the drive sprocket is 10 tooth. That's all I know.

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that's chain drive. 10 tooth drive and probably 44 rear. I run 11/36

 

[Nova1971]

Speed (mph) = rpm ÷ total reduction × wheel diameter × ⚻ ÷ 1056.

6800 ÷ (4 × 41/11) × wd (?) × ⚻ ÷ 1056 = mph

my tach reads 10,800 and with 11/36 gearing I can't pass 54mph. Does this sound right or is my tach hooked up wrong?

 

[Sidewinder Jerry]

my tach reads 10,800 and with 11/36 gearing I can't pass 54mph. Does this sound right or is my tach hooked up wrong?

What's your outer tire diameter? How are you determining your speed while riding? What does your tach stay at during WOT on level ground?

At 10800 rpm on 26" tires with 11:36 drive ratio mathematically you could do 62.3 mph. The big question then becomes is are you producing enough horse power to do it???

If you're doing 54 mph on 26" tires using an 11:36 ratio your rpm would be 9368.

If you're using 24" tires with your 11:36 then it'll take 10,149 rpm to do 54 mph. The 10,800 rpm would produce a speed of 57.5 mph.