Valve Cover Rubber Needed? (Was Oh Crap!)

[RossKean]

That part is listed for a BUNCH of Yamaha applications - motorcycles, boats, ATV, snow machines etc.

I don't think I would want to leave it out. Might be OK or might not...

 

[dcarver]

Yo DC. I have a brand new timing chain I have never used. If you can't get on quickly I can priority mail it to you.

Thanks Skooter. Not yet decided to replace or not.

Do timing chains really stretch?Like drive chains of any sort, you will get elongation as the chain wears but this apparent "stretch" is a function of wear in the pins/bushings, not stretching.

Ok not literally stretched, but severely stressed. Sounds like he hit the stater and it locked the motor. Not quit as bad as actually running and locking but stessed none the less. But as said better than piece dropping into the crankcase.

Yes. Hit starter, rotated maybe 20 degrees and locked up. Knowing the chain was under duress I spent 2.5+ hours loosening CCT bolts within 2 threads of out which hopefully removed some tension.

Just now examined the chain in the crank gear area and find nothing visually wrong. Secured chain to top sprockets then lifted exhaust chain follower allowing slack at crank gear. Carefully examined each link visually with magnifying glass looking for link difference pin-to-pin and plate separation spacing. Then carefully 'seated' the chain to crank gear teeth feeling for engagement issues.

So far all looks good, chain wise.

CCT appears to be in good condition too. I have a new one to compare with, both feel identical in spring wind up and release smoothness.

Next step, install CCT, inspect entire length of chain and be sure timing hasn't slipped.

 

[Fred W]

I guess you would have to calculate the centrifugal force of a chain of that length running at 9k rpm and decide if it would deflect the chain between the two cams. The other two long runs, running down to the crank and running back up to the intake cam sprocket are both taught with curved guides to keep them from deflecting outward. Im thinking the engineers decided that if there was any slack that caused that chain to deflect outward that it wouldnt take too long for it to saw through the alloy valve cover. Seems like cheap insurance to securely glue that sucker back in there where it belongs.

 

[dcarver]

That part is listed for a BUNCH of Yamaha applications - motorcycles, boats, ATV, snow machines etc.I don't think I would want to leave it out. Might be OK or might not...

I guess you would have to calculate the centrifugal force of a chain of that length running at 9k rpm and decide if it would deflect the chain between the two cams. The other two long runs, running down to the crank and running back up to the intake cam sprocket are both taught with curved guides to keep them from deflecting outward. Im thinking the engineers decided that if there was any slack that caused that chain to deflect outward that it wouldnt take too long for it to saw through the alloy valve cover. Seems like cheap insurance to securely glue that sucker back in there where it belongs.

I guess you would have to calculate the centrifugal force of a chain of that length running at 9k rpm and decide if it would deflect the chain between the two cams.

I have not the brain power to perform such a cacluation.

However, I do have enough wallet to order part today, as well as new-to-me iggie coils complete with caps from a 17k 06.

Still on the fence if a new cam chain is needed.

 

[dcarver]

Ok, I gotta know. How do you screw so much stuff up for a simple valve adjustment?

Worse than that SkooterG.. Just a valve cover replacement as I phooked up the gasket at last valve adjust!

 

[Fred W]

That is easy enough to do. Even when you get everything else out of the way its hard to keep the gasket from getting mugged up. Especially if it isnt securely glued to the cover with some gasket goop.

Ran into that earlier today. Tried to use some sticky grease, but it wasnt sticky enough to keep the gasket in its groove. High temp silicone sealer to the rescue.

Sometimes trying to take shortcuts becomes the longest way.