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Old 06-24-2014, 05:36 PM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Just set up a new lower engine, and now the rear wheel locks when clutch is engag

Originally Posted by sergman89 View Post
First, thank you for your time.I just bought a lower engine from and then I bought a new piston as well because my old piston had an arrow shaped chip of metal missing from its top side. This will be a HUGE help guys, and I swear give me 1 more year and ill be a pro returning the favors!
Below are all the factors I feel may be effecting this.

The issue is that the piston seems to get stuck and locks the back wheel instead of turning over. I thought maybe some starting fluid, but that only works if the piston is moving inside.

When I was trying to put the chain on the motor, I had to loosen the head bolts because there was to much pressure and it kept me from turning the bolt WITH the sprocket.

Apparently there are quite a few different kinds of pistons though or its just a way for them to market. When installing the new piston and everything I only used a little bit of oil supplement to glide the piston into the upper engine.
Pix would help so we can see exactly what you have, but I'd like to add here a question.

You do know that all you need to do is remove the spark plug from the head to relieve th compression?

You never need to loosen the head inorder to relieve compression for turning the engine over.

Im not sure what you mean by "oil supplement" you should always lube piston and cylinder with a light coat of 2 stroke oil before installing piston.

Some pistons are made with an arrow shaped indent in the piston top.

A new engine is gonna be a little tight and be sure that with all else done right that you have the clutch cable adjusted correctly.

I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!

Last edited by mapbike; 06-24-2014 at 05:40 PM.
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