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Old 01-01-2016, 01:04 PM
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sbest sbest is offline
Motorized Bicycle Elite Member
Join Date: Nov 2015
Location: Nova Scotia
Posts: 248
Default Re: Engine won't go past 30MPH

Leo, I have 3 motors. The first 66cc 44t 26"wheel I got would not go over 30mph, and would not climb moderate hills at all. The new Grubee Skyhawk 66cc 44t will do 35-37mph and will climb moderate hills with ease. With a few mods I am getting the Skyhawk to climb steep hills at over 30kph (18mph). Under that speed I still lose torque. I agree with your post, but would add that torque adding mods are something to consider as well as low gears.
These motors are not all the same. It is obvious the new Grubee Skyhawk is better balanced than the older 66cc motor and will run to higher rpm and makes slightly more power. I have the older motor apart right now and see no counterbalancing on the crank. The cylinder porting looks similar but has some huge casting flaws. I've cleaned up the porting flaws (no mods or further porting) and while the case is apart will try stuffing it to see the effect. I'll take a guess at what to drill for counterbalancing the crank. Crank balance and piston ring thickness are big limiting factors for these engine's rpm.


Last edited by sbest; 01-01-2016 at 03:09 PM.
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