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So, the "project bike" that I have been riding around for about 2 months quit on me on saturday. I finally got the valve cover off to start looking and found this:




The part that has the red box on it was sheared off and the bolt and piece were missing. As well, the lobe on the oppisite side had a stress crack.

I got the engine out of the frame last night and got the camshafts out so I could get in there and look, and I don't see much damage so far, and I see most of the broken parts, so I think I can get her running again. My question iis, however, what might have caused this to break? Any thoughts?

Any real pictures of the damage? It's easier if you can look at the pieces.

I keep forgetting to take pics when I'm at home (writing from work now). I will try to remember to snap a pic later today.

Here are actual pics of the damage, and one of the piece in the engine

Wow...

I'd say off the top of my head that was just a manufacturing defect. That's the peice that holds the camchain sprocket in place... So either your cam stopped for some reason, causing the chain to torque back and reef on the sprocket... or it was just a weak spot waiting to brake.

Have you gone any deeper into the engine?

No, I haven't gotten deeper yet, I hope to get a little deeper tonight, or Saturday.

I wonder if the sprockets go on in one direction only and I had it flipped over. That would cause stress around that point when torqued down, or I guess it could just be a defect as you said. I'm not sure that the cam stoped, the engine will crank over until the chain binds on the pieces that have fallen down, so I just don't know. My hope is that nothing got down in the transmission and caused any damage.

I did get a little chance to tear further in to the engine last night. I got the cylinders offand peer'd down into the engine case. I don't see any major damage to any gears or the big camshaft. I did drain the oil and there was some metal shavings in the sump, but not a ton. I think its looking like its going to be ok. I can still hear a couple of pieces (like the bolt) in the bottom of the crank case, so I will, unfortunatly, have to split the case to get those pieces out. YUCK!