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Author Topic: Rear head problem  (Read 481 times)


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Rear head problem
« on: July 19, 2017, 01:47:42 PM »

Hello all, New to the forums.

Have a problem with my Hyosung gt250r engine. I originally removed the engine from the bike for a faulty cam chain tensioner. Once the engine was removed i removed both of the heads to see which one of the cam chains was loose, Then removed the stater motor cover to reveal the magneto, When spinning it it spins, Then all of a sudden it sounds like it hits something, A bit of a thud and wont spin anymore, If you remove the rear cylinder cam chain tensioner, So the cam chain is loose it spins freely, As long as the rear cam chain is not spinning around if that makes sense.
So the problem must be to do with the rear cam chain ?

We have taken both heads off, The pistons are completely fine, The piston barrels are fine, No scratches or anything like that. There is no metal in the oil.

What do you guys think it could be ?


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Re: Rear head problem
« Reply #1 on: July 19, 2017, 09:36:40 PM »

If you didn't pay close enough attention to the cam timing when re-fitting the chain, it could be a valve touching a piston.
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Re: Rear head problem
« Reply #2 on: August 16, 2017, 12:55:21 AM »

Also, if the cam timing chain is not tensioned properly and you turn the flywheel counter clockwise this could happen. 

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