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Old 04-28-2014, 07:58 AM
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SuperDave SuperDave is offline
Motorized Bicycle Elite Member
Join Date: Sep 2011
Location: Panama City Beach, Fl. USA
Posts: 180
Default Re: Top Speed, 80cc Chinese motor? what is the record?

Originally Posted by Jumpa View Post
I ah feel ya Dave!! 39 M.P.H. was my top speed going down a hill 32 level
Dave as i bet you already know 90% of the vibe is coming from loose motor mounts, I had one mount vibrate out and the vibration was ten times worse so after I fixed it & I went over the other 3 bolts and glued some rubber tubing inside the mount as well as the saddle clamp.

I got on it , got up to speed and it was sooo smooth hardly any vibration at all . Still feels like its gonna fragment between my legs though at top speed!~
While using some kind of elastic isolator might sound like a good idea, it has been the experience of many that it will cause more troubles later. By isolating the vibes from the frame, the motor mount studs end up sustaining the majority of abuse, oftentimes resulting in broken studs. Upgrading the factory provided studs with Grade 5 hardware or better will help with this, but it won't prevent the studs from stripping out the threads from the case, another problem that has been reported.

Best suggestion: Remove the studs & make sure the threads are tapped all the way in. The Chinese workers often cut corners here & won't take the extra minute it requires to do it all the way, they are encouraged to crank out as many units as possible, so to save time they only tap the threads 1/2 to 3/4 the depth of the hole. This means less grip of the stud in the case & may result in stripping. Next up, replace the studs with good hardware. Avoid the temptation of using AllThread Rod & cutting it to length, even if it is grade 5, the act of cutting creates friction & heat, weakening the temper & strength. I got my upgraded precut studs from JuiceMoto, but other vendors sell them too. Lastly, use locktight & double nuts, red locktight for the case & blue locktight for the nuts.

There are a few cures for vibration, using a quality CDI such as a Lightning or a Jaguar helps by recurving the timing advance to be more advantagious to our China Girls. It has been said that the factory ignition provided is better suited for 4 stroke equipment that operates at a constant speed, such as rototillers, lawnmowers & sump pumps, there's too much advance built into them. Aftermarket CDIs correct for this. If that is too much for your budget at this time, a Rocket Key can be used to replace the half moon key under the magnet rotor, retarding your ignition in an old school manner(I've done this, because my SuperRat uses a 1Peice magneto, an aftermarket CDI isn't an option for me). Some folks have reported using a Dremil Roto-Tool to wallow out the mounting holes in their magneto in an effort to have some timing adjustability.
By the holy power of Love, Life & Laughter, I commend you to Go Forth & Be Awesome!
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