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Old 04-28-2014, 09:59 AM
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Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Top Speed, 80cc Chinese motor? what is the record?

Originally Posted by SuperDave View Post
There are additional methods available to reduce vibrations in a China Girl, which is one of the biggest limiters of RPM & speed, such as internal balancing. Most of us reading this do not have the equipment, knowledge base or skill set to do this ourselves. You might take your motor to a reputable machine shop with experience in 2 strokes or just purchase a prebalanced assembly from Dax, Arrow or CR Machine. Some have reported varying degrees of success by lightening the piston by drilling holes in it. But unless you have experience in rebuilding motors, I wouldn't recommend it, as it is far too easy to remove too much or cut the wrong location, resulting in a junk engine that will never run again. I tried using a lightweight titanium wrist pin & I can report that while it did ease vibrations, it didn't last, the titanium alloy used turned out to be too soft, it deformed within 10 miles & resulted in internal damage. At present, I'm awaiting FedEx to deliver me a new top end kit that I bought last week.
I know this doesnt go with the thread topic but I wanted to say regarding the titanium wrist pin that my engine that is running one has a little over 30 miles on it now and its holding up so far with the aluminum bushing instead of the needle bearing, I did blow a head gasket the other day so Im thinking when I pull the head I may as well pull the jug and see if I can see or feel any signs of wear between the pin and bushing, if so Im gonna pull it out and consider it a failure, I have been running the engine pretty hard the last few miles just to see how it would hold up under the high rpms and vibes from this engine, I think I blew the gasket because the engine was so hot after running it at wide open for about 3+ miles the other evening, still no knocking or signs of pin and bushing failure so maybe its a good combo... time will tell unless I see wear when I check it out maybe next week.

This bike only tops out at 36mph vibes are better than before but still uncomfortably high at top speed.
I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!
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