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Old 07-01-2010, 10:43 PM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
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Default Re: The inside of my thrashed 66cc engine

Originally Posted by junked View Post
No, play between rod and crank is not normal and would only get worse very fast if you were to just replace the jug, piston etc. You probably have damage to the crank pin also, not just the bearing. I would buy a new engine.
Thank you "Junked" and all who have commented on this thread,

I have many years of experience working on 4 stroke engines and have rebuild and modified many of them to stock and/or performance specs. but these cheap china 2 strokes are a new animal for me and since the rest of the parts in these engines seem to have such loose tolerances I was unsure about the amount of slack that is acceptable in the lower roller bearing between the rod and crank journal, this engine had a clacking & knocking sound to it from the very begginning and now I am thinking that this sound was due to the lower bearing having all that slack all along, from the way it looks there were never enough rollers place between rod and crankshaft from the factory, there is enough room to put maybe at least 3-4 more rollers in there, I bet one of those rollers got turned at an angle between the rod and crank and then broke under the stress and this may be what came up and hung between the piston and the transfer port in the cylinder, I know something did, because the ring retainer pins were still in place and intact when I pulled the piston out of the cylinder. well looks like this is a spare parts engine now, Dang-it and it was so darn smooth running for it's short clacking life.

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