Cam Tensioner Goes Pop Pop Pop

[gene xs]

I am resuscitating a new to me '78 XS650 E. It has sat for at least 6 years.

I got to the point of adjusting the cam chain tensioner. When I kick it over the tensioner intermitantly pops out 1/8 to 1/4" and goes pop pop pop as I kick it over. When it's still, the tensioner is even with the holder, as it should be.

Question: Is this normal? If not, what might be causing it?

 

[Downeaster]

Just guessing here, but that sounds like a kinked or dry chain.

You know how a dry or kinked drive chain will "pop" going over the sprocket?

Perhaps just running it in with fresh oil will loosen it up. The tensioner moving that much is not good, but I'm not sure it would hurt anything to run it that way briefly.

Change the oil if you haven't already, pull the plugs and kick the engine through several times to get the cam chain covered in oil and then let it set for a day or two and see if it loosens up.

 

[5twins]

The occasional large pop out is normal when turning the motor over by hand or with the kicker. It won't be doing that while running. The valve springs snap the valves shut. That pushes the valve's rocker arm which, in turn, gives the cam lobe a quick push. That tugs the chain taught which makes the tensioner pin "pop".

 

[angus67]

For now, adjust it till its about 2mm proud of the adjuster.
once you get it running, adjust it while its running. I think rg has a utube of it.
it will be hot in there, and some oil will dribble out.

 

[gene xs]

I got the bike running and had a very bad clatter from the cam chain. I had to pull the top end off anyway to address leaking valve seals. Here's what I found:

Cam chain seems tight enough on sprockets - I can pull it only about 2 mm off the sprocket.

Cam chain links are not bound up (at least they are not after the engine has run).

Cam chain has been broken apart in the past - The master has been replaced.

The tensioner guides both look fine. They look to be repops - the front has "A0147" cast on the side if that's a clue.

So everything looks fine to me inside the engine.

But, the tensioner is missing the damping washer.

So my question is: could the lack of a dampening washer be enough to cause the clatter I heard while running?

Thanks!

 

[retiredgentleman]

Yes, a missing damper can cause a tapping noise.You can use a copper washer as a damper.

 

[5twins]

What makes you think the chain was split and the master link replaced? Might it be the crude look of the riveting job? If so, that could very well be from the factory. That's how they did them. Here's what my original looked like. "Crude" is actually being nice when describing it, lol .....

 

[gene xs]

That is pretty crude, alright. Mine is lopsided like yours, but does not have the indented line anywhere at all.

 

[TwoManyXS1Bs]

The number on the front tensioner identifies it as an aftermarket item. More info here:

http://www.xs650.com/media/albums/1640/

Being able to lift the chain 2mm off the top of the camshaft sprocket indicates a stretched camchain...