Valves kissed the piston!!!
Posted February 09, 2008 - 06:57 PM
Posted February 09, 2008 - 09:14 PM
Maybe when your engine seized, the sudden shock of stopping caused the sprocket to slip on the cam. then when you rebuilt and set the timing by the marks, the lobes would not be synch'd properly. Is your cam sprocket adjustable or pressed on? Even pressed on it could slip. There was someone on here a few weeks ago with a stock cam sprocket that slipped.
Posted February 10, 2008 - 06:32 AM
One more thing I discovered that explains where on the piston the vavles hit: The piston in the cylinder can be rotated a tiny bit. Probably enough that a valve out of sync would hit it on the side of the valve indentation on the piston. No way in hell I am tearing into a bottom end to replace a crank. I don't have the patience or the skill. My last question before deciding to dump the bike for pennies or fix it: If I leave the crank as is, replace the topend valves and have the timing right, is there any reason why the valves would ever come close enough to the piston to kiss it whether it be on the shoulder of the valve indentations or in the center of them?
Posted February 11, 2008 - 02:16 AM
Firstly if the bike was running fine before you seized it , I would suggest the amount of movement in the big end is normal ( piston rotatation). Unless it ran out of oil and has done a bigend. This would allow the piston to come up too far hitting the valves.But doesn't sound like it.
Secondly you say the exhaust cam is different (new). It's possible that it is incorrectly timed. Which would result in the inlet cam being out of timming also. I''m talking timing dots. most unlikely though
Thirdly did the guy's who rechromed your cylinder grind the surface? If so reducing valve to piston clearance.
Wiseco pistons are widely used and this is the first time I've read that one has kissed the valves.
I would put my efforts into checking the valve train. That includes valve timming with a degree wheel.
If the cam lift of the new cam ,with it being higher, it would only account for the exhaust valves hitting not the inlet.
Posted February 11, 2008 - 04:18 AM
Posted February 11, 2008 - 07:54 AM
Posted February 11, 2008 - 08:16 AM
Wonder if that's the case and it's also what is making the piston turn counterclockwise on you like that.
Doesn't account for your timing issue, but it's a start to look for what might be causing the piston rotation other than a bad crank....
Posted February 11, 2008 - 08:35 AM
Posted February 11, 2008 - 09:13 AM
Posted February 11, 2008 - 09:37 AM
Keep us posted - maybe before ripping it all down, see if you can swing the piston back to the left (in pic) with your finger and see if it was an illusion first before going through all that trouble...
You can get the manual off the link in the stickies up top.
Posted February 11, 2008 - 02:51 PM
Posted February 11, 2008 - 03:21 PM
Posted February 11, 2008 - 03:56 PM
Posted February 11, 2008 - 06:10 PM
Posted February 11, 2008 - 07:06 PM
Posted February 11, 2008 - 07:43 PM
Did you forget the clip or was it not fully seated, popped out, and is now floating around in the engine? If you are not sure, I'd remove some covers and look around in the bittom end.
Posted February 11, 2008 - 10:37 PM
Unfortunately you now have bent valves and need to get that fixed. If they are stainless they can be reground. I would not regrind titanium because you'll
take the nitrite off and they will wear real fast.
At top dead center of the exhaust stroke the intake valve is opening and the exhaust valve is closing. So yes, both valves are opened. How far open is relative to cam specs. You should have a minimum of .050 (imperial) valve to piston clearance for safe operation.
Posted February 12, 2008 - 03:24 AM
As others posted, replacing all five is cheap insurance. Seats will be fine.
Look at the bright side, you now have a fancy ashtray. Another positive is it was not the crank or rod.
Posted February 12, 2008 - 05:20 AM
I also hope that on pic 2 where the top of the crack is - that little triangle piece made it through to the sump and comes out with the oil change (I'd be draining into a clean container and then straining the oil to make sure) - it may not be big, but it can do damage.
By the looks of it, the wrist pin slid sideways and caught on the bottom lip of the bore and the force split the piston - any marks where it hit the bore? - it could leave a dent that protrudes into the bore some - you might have to have the bore refinished else it'll wear on the new piston.
Also, if that happened, it's like taking a sledge to the rod and bottom end, so inspect everything very carefully for excess free play or damage since your big end bearing could have taken a beating on that one hit.