I seem to have a little problem. I have a 1999 400ex. A friend and myself were tearing down the top end for a rebuild. We already had the head off of the motor when we realized part of the timing chain had fallen into the case and kinked itself. The only way that we could get it out was to rotate the crank clockwise. We only moved the crank a hair more than a quarter of an inch. I know this is a bad thing because of the decompression system. The top end on the motor is still off. What should I do from here? If I rebuild the top end will everything be ok or do I now need to rebuild the bottom end? Any help is greatly appreciated. Thanks.

 

Although common sense knowledge dictates to never turn an engine over backwards, I've never seen an engine damaged from doing so slowly and carefully. Besides, you already had the decompressor out, it's mounted on the cam (unless it's been circular filed ala aftermarket cam).

 

to get the cam chain tessioner tight machinics turn the engine backwards slowly this helps get it just a little tighter so you should be fine if you line all the timing marks up when you put it back together
good luck

 

Thanks for the help.