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Old 07-30-2009, 11:46 PM
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MikeJ MikeJ is offline
Motorized Bicycle Senior Member
Join Date: May 2009
Location: Colorado Springs
Posts: 82
Default Re: weight limit on 80cc engine

I second the recommendation to get a shifter kit from Sick Bike Parts. I installed mine only two weeks ago. I weigh 245 lbs. A test hill I chose is 250 feet vertical climb in about half a mile. Another factor is the hill altitude is almost 7000 feet air density above sea level on a normal day. The air is thin. On a hot day, the air density can reach an equivalent of 9000 feet above sea level. Some people from sea level have a hard time breathing in a brisk walk. Any naturally aspirated engine here puts out only 3/4 of what it can produce at sea level. My 80 cc engine can't make the entire hill by itself even in first gear. So when I am under 10 mph, I throttle back a bit and pedal. On flat highway, cruise at 30 mph in 4th gear and only 80% of redline rpm. 35 mph on declines. Only because I know it has good brakes! The engine had only 75 miles on it at hill test time. It is not fully broken in yet. I expect performance to get better at lower altitudes, in colder temperatures, and with another 100 miles on the engine.
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