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Discussion Starter · #1 ·
I have a 2014 675r with nearly 40,000 miles as my primary commuter. Riding home the other day I felt a light pop and then had reduced power. It got me home and I started tearing it down. Low and behold one of the exhaust valves broke off and was disintegrated. The valve did make a couple impacts with the piston but it doesn't seem cracked. Not having my bike is killing my commute her in southern CA. So my question is just slam a valve in it and get it back on the road, tear it all the way down and replace the piston, or replace all pistons and valves.
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Tear it all down! The sharp edge of the piston damage are detonation triggers as well as major fatigue risers. It will surely fail if you just put in a new valve. Likely your cylinder has some some scaring as well.

ALSO, you likely have some bearing damage on the lower end... do a full tear down and check everything, else you may be buying a spare engine (if you'd like to ask how I know...)


Now the big question, how did you toast a valve? Tune or tight valve clearances are my first guess
 

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Discussion Starter · #3 ·
Tear it all down! The sharp edge of the piston damage are detonation triggers as well as major fatigue risers. It will surely fail if you just put in a new valve. Likely your cylinder has some some scaring as well.

ALSO, you likely have some bearing damage on the lower end... do a full tear down and check everything, else you may be buying a spare engine (if you'd like to ask how I know...)


Now the big question, how did you toast a valve? Tune or tight valve clearances are my first guess
No tune, will never know the tolerance on that one but I checked the rest before I pulled the basket an theu were all good. I have had an exhaust leak for a while which in the process for the valve I found no gasket on that cylinder header but hard to imagine an exhaust leak causing this but maybe.
 
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