When should you replace a cam chain?

[Samuraiace]

I'm doing a top end rebuild, new guide, gaskets, rings but I'm curious if I need to replace my cam chain. I know it's probably the best idea to just replace it but how do I know when it needs to be replaced? Is there any way to check while I have the engine apart?

 

[DLD1]

As long as you haven't used up all the adjuster it should be OK. I haven't experienced or heard much about failures or excessive stretching of cam chains. I would inspect it and the guides, and if it looks good I'd leave it alone.

DLD1

 

[650Skull]

Excessive wear, causing the chain to lengthen or stretched shows up on points plates when the points run out of adjustment. often the owners would file the hole in the adjustment plate instead of replacing a cam chain.

XSjohn used to use old cam chains for his 8.1 motor. he found most of the stretched, (wear within tolerences), chains were still in good condition.

 

[Samuraiace]

Cool this will save me a bit of cash for other parts to get me rolling thanks!

 

[5twins]

If you have anywhere near 20K on your motor, it's probably best you replace the chain. Sure, they can last much longer than that if properly maintained (checked/adjusted every 1000 miles) but most never were.

 

[1974jh5]

I've always been a 'while I'm in there' kind of person. It sucks to rebuild a top end then find out six months later it all needs to come back apart because the cam chain's slapping or at the end of its adjustment.

Also, as the chain stretches (actually this is due to wear, not stretching) the cam timing will change. It will retard the cam timing which can help top end a bit at the cost of some low end snap.

 

[650Skull]

I've always been a 'while I'm in there' kind of person. It sucks to rebuild a top end then find out six months later it all needs to come back apart because the cam chain's slapping or at the end of its adjustment.

Also, as the chain stretches (actually this is due to wear, not stretching) the cam timing will change. It will retard the cam timing which can help top end a bit at the cost of some low end snap.

Correct......Altered my post. Using common language


In no way am i advocating not to change a cam chain if the adjustment shows the chain is worn/ stretched. Each has to be judged on its merit, mileage, or amount of adjustment

 

[Samuraiace]

Well I don't know what the engine has for mileage the cluster isn't from that bike, it was in a shipping crate for awhile. The guide was trash but the chain looks in good condition. I'm not sure about the adjustment, how do I check if it's stretched too far or no longer usable while the top end is apart?

 

[650Skull]

If in doubt, better to arrr on caution

 

[Samuraiace]

I think I've just been avoiding the inevitable , time to purchase a chain.

One other question, can I replace pistons from one engine to another?

 

[CDNTX650]

I wouldnt....Pistons and bores wear in a shape together. I would bore and re-ring if your that far. Unless you are keeping the same pistons and bore and just fitting them to a different bottom end, then you might be okay

 

[zmaxmotorsports]

Does your manual list a max length/stretch allowed for a certain number of links?

 

[650Skull]

One other question, can I replace pistons from one engine to another?

It is done but the pistons and barrels would have to be measured and be within tolerances.

 

[weekendrider]

Excessive wear, causing the chain to lengthen or stretched shows up on points plates when the points run out of adjustment. often the owners would file the hole in the adjustment plate instead of replacing a cam chain.

So in the TCI ignition it would manifest itself as advanced timing also?

This may be of interest. Maybe it isn't the length that is the problem?
http://www.allredsmotorsport.com/id61.htm

 

[XSLeo]

No, The TCI is triggered by the pickups on the crank, so the cam chain has no effect on the ignition timing on the TCI engines. It can effect the cam timing.
A too worn chain can let the tensioner hit inside the cam chain tunnel before it runs out of adjustment. It can also let the cam jump time. Both of theses things happened on my 75.
Leo