Motorized Bike Speed.

[DaveenBavari]

I have an 80cc Motorized bike and it runs great. I have a 28 tooth rear sprocket on a 26 inch wheel. There are people on here who are doing 45-50 with a 36 tooth sprocket but I can only do around 35 and when I'm at that speed the engine is at the very top of its rev range. Any ideas on what it could be?

 

[crassius]

iI you slip the clutch a bit at that speed, do the revs go higher?

 

[Street Ryderz]

I have an 80cc Motorized bike and it runs great. I have a 28 tooth rear sprocket on a 26 inch wheel. There are people on here who are doing 45-50 with a 36 tooth sprocket but I can only do around 35 and when I'm at that speed the engine is at the very top of its rev range. Any ideas on what it could be?

At 35 mph with a 28t gear on 26" wheel your engine is only turning 5300 rpm so not the top possible rpm,Your engine is strugling to turn the smaller gear!Guys using a 36t gear and 26"wheel the engine is turning between 9 and 10 thousand rpm to hit 45-50 mph.So your engine needs to make more torque to turn that gear or go to a higher tooth count!

 

[Timbone]

I am running a 40T and that's very big, cruising in the 30's. I always pedal out of a start, because the 69cc can't pull it off the line. The sweet spot is 36t to 41T since 44T will not get you to 30 unless you mod up.

 

[DaveenBavari]

The 28 tooth works very well for me. I'm only 125 pounds so the acceleration is still pretty good. I do have to pedal to a higher speed before I let go of the clutch though. It doesn't feel like my clutch is slipping but when I'm at 35 it sounds like the engine is about to explode. So it has the torque and power to get up to speed.

 

[Timbone]

By my calculations, a 28T rear sprocket should have you at about 47 mph at 7000 rpm. 35 mph at just over 5000 rpm...

 

[Street Ryderz]

Thats odd because as I said above with that gearing on your wheel the engine rpm would be around 5300-5500 and thats just below the normal sweet spot for these engines.That being said if you are hearing high rpm then yes somthing is slipping in the clutch or something!