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Blew up my motor

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NinjaBob:
I have had no major troubles with the 7 other kaws stacie and I have owned. My 08 Concours is still running fine at 170000. Ran at track day like a champ.

OldButNotDead:
Sorry, I missed the part about the exhaust valves.  More familiar with FJR's.  If you have just done on valve clearance check on FJR's the one thing that is easy to screw up is skip a tooth on the timing chain.  Normally that would be immediately made apparent and the engine would not just stop.  If the cam timing was off, the cams would not necessarily be damaged.  That engine just stopping is the part that doesn't make sense to me on a purely mechanical failure.

normkern:
Diagnosis, based on what's been presented here:

Important facts- Valve gear problem + Valves adjusted 500 mi ago= Related.
Bent/broken valves means camshaft went out of time. (Over revving could theoretically cause this, but the ECU has a rev limiter that cuts ignition well before the mechanical limit is reached.)

Cam sprocket bolt heads are sheared off. That is a key fact here, but is it the cause or the effect?

There are several ways this could have happened.

1. Sprocket bolts could have been overtightened when they were assembled after the clearance check, weakening them. Not very likely.

2. The camshaft bearings could have seized, locking the camshaft and causing the sprocket bolts to shear. The camshaft bearing caps are numbered and have to be reassembled in the original positions on he head. If two of them got switched, the bearing surfaces do not mate correctly, making the camshaft much harder to turn. A camshaft bearing could overheat and seize, shearing the bolts.

3. A valve stem broke and the head of the broken valve jammed between the piston and the other valve as it was opening at the end of the exhaust stroke. This would prevent the valve from opening and lock the camshaft. That would shear the sprocket bolts at the surface where the sprocket mates with the camshaft hub.

Collateral damage:
One of the falling boltheads got the tine on the timing rotor while the crankshaft was still turning.

In addition to damage to valves, there will be damage to pistons, possibly bent connecting rods. Broken valve heads getting crunched in the cylinder can damage the cylinder head and cylinder walls as well. Since the cylinder block is part of the upper crankcase casting, you may find it best to find a used motor and do a swap, rather than fix this one.

It's these nightmare scenarios that make me paranoid about doing valve adjustments on complex bikes. Sorry to have to be so negative, Bob. :-(

Norm Kern 

NinjaBob:
Thanks for the analysis Norm. I did not remove the sprocket during the valve adjustment, no need.
No sign of galling or scoring of the cam bearings, does not look like it seized. I verified that the cam caps were all in proper position.
Scenario # 3 sound very likely. No plans to try to fix. Used motors are available at at reasonable price but don't know what I will do at this point. Busy getting the 08 ready for STAR.

mi-msta:
Bob -


Have you checked the cam chain? I had what sounds like the same thing happen on my 2004 GSXR 1000 -- cam chain snapped - no jolt no nothing, bike just coasted to a stop. All 16 valves were bent. The key though is that the starter - ran very freely --
I was lucky in one respect the chain didn't bunch up and cause further damage - my guess is that your did.


Just my 2cents worth.

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