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Valve to Piston Contact-damage?


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During my recent hot cam exhaust fit in my original fitment I was 1 tooth off, as my TDC wasn't quite in the centre of the inspection hole i did a manual rotation of the crank to realign and there was a definite loud knock and resistance when I rotated and I'm thinking this was valve to piston contact.

As it was only wound over once (I *might*) have done it twice I can't quite recall, what chances are there I might have broken or valve or something else?

The bike has not been started, head has not been pulled but it is back together.

Should I pull the head off and check, or start and hope?😏

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You may have slightly bent a valve, pull the head off and check the seating to make sure they are sealing. I am not 100% sure but a leak down test or compression test may also help if you don't want to take the head off. Do a test, then give a couple of squirts of oil down the spark plug hole, repeat the test. If the result is better then you may have done some damage. It's a pity that it's late night in the US, I am sure Eddie would know what to do.

Good luck mate.

Luke

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During my recent hot cam exhaust fit in my original fitment I was 1 tooth off, as my TDC wasn't quite in the centre of the inspection hole i did a manual rotation of the crank to realign and there was a definite loud knock and resistance when I rotated and I'm thinking this was valve to piston contact.

As it was only wound over once (I *might*) have done it twice I can't quite recall, what chances are there I might have broken or valve or something else?

The bike has not been started, head has not been pulled but it is back together.

Should I pull the head off and check, or start and hope?🤣

Hey David..I know you are wanting someone to tell you it will be ok not to check if you have caused any damage...😏:cheers::ride:

Its your bike mate, are you willing to risk it...???..😏

I think you know what should be done....

Keep us posted ,Cheers, Craig

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any of the valves have way too much clearance now?

No they are all within spec, both exhaust are sitting on 0.20mm now. I have a .23mm feeler gauge which doesn't fit and the .20mm slides in nicely with a little room to spare so I guess clearance is slightly over .20mm. Same clearance results before I pulled the SM cam as I wanted to measure before it came out.

Could it have been the decomp. making that noise?

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It will give some more RPM up top . I noticed the exhaust note aswell , it sounds more like a thumper , greg

Yes I agree on the exhaust note, I've only taken it to 100klm/h but there's a bit more pull up top for sure.

I ripped myself off not buying both at once coz now I'll have to pay for shipping again when I buy the intake.😏

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I'm a worry wart, it started up and runs fine.

First thing I noticed was slightly different exhaust note, have only done a brief break in ride thus far but i don't expect to notice any huge seat of the pants difference.

when building motors and not a lot of expierience .. the best thing you can be is a worry wart .

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