Pegged at 6970 RPM

[FrizzleFried]

My sons bike (66cc China Doll) w/44 tooth sprocket pegs at 6970 RPM. It won't go more...

Why?

Crappy exhaust? (It's a slightly upgraded BBR pipe...a real mini expansion chamber thing that's essentially a tick above stock... mostly in the sound department).

What would I get speed-wise with a 44t sprocket if I could some how manage to pull another thousand RPM out of it? I'm wondering if it's even worth trying for more... my "ballpark" math says I'd only get around 4-5 mph more out of her... probably not worth the effort.

 

[ImpulseRocket]

Does it behave weird or make funny noises, or does it sound good and just won't pull?

It could be crappy port timing or something like uneven upper transfers. Or maybe the cdi just lacks the juice to spark at higher rpms. I am aure I could think of a few more things.

 

[FrizzleFried]

Yeah... sounds fine just maxes out at 6970... wide open... waited about 5-6 seconds then backed off...

 

[FrizzleFried]

...maybe I should consider it a 'feature' (it is the kids bike!)...

 

[GW's Motorized]

I'd probably think it's the pipe. @coubob had one of those F2 pipes and he had a great improvement when he swapped pipes. If you want more rpm a little port work would go a long way.

 

[DAMIEN1307]

...maybe I should consider it a 'feature' (it is the kids bike!)...

In this day and age, if it were my kid, I would be building his bike with a padded roll cage stuffed with air bags all around, I sure wouldn't want him going as fast as my bike could propel him until he was at least 40 years old...lol...lol.

 

[Nickt919]

If it’s a 26” then he’s going right at 30 mph. As long as it’s running decent maybe it’s a blessing for you.

Tire Size, RPM, Speed, and Differential Ratio Calculator

Describes the process for converting a gasoline powered car to electric power

www.advanced-ev.com

 

[Sidewinder Jerry]

I'm assuming 26" tires; giving you a top speed of 29.9 mph.

 

[Whitewill1412]

I'm assuming 26" tires; giving you a top speed of 29.9 mph.

That's what Nick said ^^^

 

[Nickt919]

Jerry is usually very precise.. and correct with his answers..so it was a bit different from my answer.
I rounded off a bit…