Topic: Bolts came out of cam chain sprocket

[JimZ]

Hey. Can't figure out how to find my previous post. Sorry. Started the bike up a couple weeks ago. Loud pinging then engine seized. Just cracked it open and found that the two bolts that hold the cam chain sprocket to the camshaft had almost completely unthreaded themselves. Before I put it back together, is there something I should do to prevent this from happening again and how did it happen??? Thanks!

[flybox1]

Clean all threads with acetone, apply a high temp thread locker, and properly torque them.

[rotortiller]

Make sure they are the right bolts and torque them down to spec. Suppose you could use loctite, although I never had the need. The hardened special bolts should not have threads formed all the way to the bolt head-it needs a smooth grip area for the sprocket holes. No washer is used.

[754]

Was it grinding on the cam tunnel..may or may not have been the pinging..

[ekpent]

 Buy new ones and use the thread locker. Are you replacing the cam chain also. If it seized/stopped from the bolts hitting a cam tunnel that chain absorbed some major punishment and am surprised it did not break depending on how fast the engine may have been spinning.

[PeWe]

Medium thread locker if you want to remove the bolts again. Loctite 243 (blue) I have always used the medium strenght and never got any bolt or sprocket come loose which is the adjustable model with oval holes
Tighten the bolt according to the manual.

Important to clean the bolts and sprocket threads with acetone. Use a cotton swab or 2.

Sure that there is no alu flakes in the oil now?

[Can550]

Please do have a close look at the top cover if rocker rods/ pins have damaged the holes, wobbling around can cause various damages. Saying this from personal experience. You are lucky that that bolt or sprocket did not break. I had to replace came/ top cover, rockers, tappets, rockers rods/pins.

[jonda500]

This happened to me once when I inadvertently left them finger tight. I only made it once around the block before CLACKER-CLACKER-CLACKER-CLUNCK!! It locked up and stopped dead. Taking the cylinder cover off revealed the cam chain draped over the camshaft with the cam sprocket nowhere to be seen! I pulled the engine out and disassembled it to retrieve the pieces of sprocket - it was broken into five pieces, but seemed to be the only casualty. I put it back together with a new cam chain and guides as well as the sprocket just to be safe - disaster over, all good. (I did use blue loctite 242 on those two M7 bolts!)
John