I am just in the process of working out if i do or don't need to replace the timing chain, the symptoms are a rattle from the engine... But the bike is being rebuilt at the moment.

I am aware that a good indicator is the guides show signs of wear, and further down the line the case cover can also show signs of a rubbing chain...

My guides look good at the moment, and the lower and right hand sides look to have good tension in them, however when looking at the upper section of chain there is an amount of looseness. The two photo's show first off the chain as it is, the second when i have taken the slack out using my fingers on the small cog on the left.

Some guidance would be very welcome

Hi there, check the tensioner, if it is fully extended then maybe you need to change the chain and/or the sprokets. There is also a procedure for review of chain wear in the Haynes.
It is also necessary to check the wear in the sprokets, on both camshaft and crankshaft
Best regards
JAP

i guess the indicator is the height of the chain tensioner twincarb

the tensioner mechanism (a oil presure piston thingabob ) also has a ratchet thingy so tension can only increase without settling back down to super slack .

or thats the way its suposed to work ..

unfortumatly verry small increments in cam chain join link length mean that the pretension on the tensioner means that it has to or could mean that the overall length of the chain could be at the limit of the chain tensioner moovement ,,,worth a second look mate ..

twb did a replacement a little while ago and found that he had been delivered a chain with at least an extra link in the length ...the result was that the length of the chain apeared to be at the limit of the tensioner i guess rattle resulted ...anyhow the short story is that after replacing the chain everything came back to measureable tollerances ....might be worth searching for the thread for the pics ...(cant find it just at the moment )

I have the Haynes in front of me at the moment, and two of the checks it suggest is

a) measuring the chain length over a 1ft length compressed. then stretched it shouldnt be more than 1 to 2% extra. Can do that taking the chain and all out, so thats the next step

b) "if the tensioner plunger is found to be fully extended".... hmmm it doesnt give a sugestion of what is fully extended and what it would be like brand new! the photo's below show that the tensioner is extended to 6mm but i am not sure what the max extension should be..

looks good to me mate

Just had a look and there is up to about 20mm of adjustment on the tensioner.. so i am well within limits so all is good i think, esp with the wear on the guides is very minimal....

You're in there, you have a rattle - I would replace the chain and eliminate the doubt and if you do, best option is to count the links rather than measure chain length, it is surprising how much longer the chain is with a little wear.

My 2p. :silent:

I just went thru the same thing, after I had the timing cover off, I lined up the timing marks, and found when the two cam marks were dead on, the crank was about 1/4" or more past, so the chain was stretched. I put a new chain on and the rattle was gone, and I was able to time the bike much better. I think the thread is on this site somewhere.