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Big Mac

Engine freshen up/now need help

8 posts in this topic

I just performed a top end freshen up on my 426 and I have a couple of problems now. I will take it back apart tomorrow and I am just looking for some suggestions and things to look for before I tear into it again.

I bought a stock cylinder & piston, new rings, valve springs, keepers and valve seals. The valves themselves all seal fine so I just cleaned up the carbon and reused them in in the same locations. I am not able to start it via the kick start, I have to give it a running jump start (leads me to believe timing is off). Also have a knocking noise that seems to be coming from the head and it really has me scared. Only ran it about 1 min with all that noise so I hope I didn't do any damamge.

I also run a 450 cam for the auto decompression but was running that for quite some time before the rebuild.

Anything you guys can suggest would be apprieciated. Thanks in advance.

Chris

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sounds like your piston is slapping the cylinder. or your piston is hitting your head. make sure you put your piston on the right way.

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Sounds like its out of time to me. The knocking sound was probably a valve kissing the piston. Never try to push start a bike if you can't start it with the kicker. Good luck!

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Sorry for the late reply. It was a timing issue. I took the head off and the two outside intake valves were just kissing the piston. I took them out and checked to be sure and they were fine. Not bent or any damage measurable. Recehcked valve lash and timed it again. It started on the second kick and no more piston slap. I was so happy and will be riding this coming weekend again. Thanks for the responses guys

Chris

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I took the head off and the two outside intake valves were just kissing the piston. I took them out and checked to be sure and they were fine. Not bent or any damage measurable. Recehcked valve lash and timed it again. It started on the second kick and no more piston slap.
How does it feel to be the luckiest man in Texas?

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How does it feel to be the luckiest man in Texas?

It feels great. I would rather be lucky than good any day. And I usually am.

It rode great this weekend. No problems or hiccups of any kind. My buddies were quite impressed with the new power as was I . Thanks again Thumper members!!!!!

Chris

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