How to check cam chain tensioner

Do you have to take the whole engine apart to get at it?

like taking the carbs off or anything?

 

A lot easier if you do take the carbs off.

 

You should also be checking the chain deflection (tension) between the cam sprockets once you've replaced it to make sure you have sufficient tension. 1/4 to 3/8 inch deflection is recommended. No good just taking it out and putting it back. Take the cam cover off and do it properly. Prior to taking the tensioner out you should also be zip tying the chain to the cam sprockets to ensure it don't jump a tooth under slack. Yamaha went tot the trouble to bore holes in the cam sprocket so this could be done............

 

I admit I had the carbs off when I checked mine. However there is a fair bit of work to get the carbs off. I was about to pull the head off mine to remove a stuck plug but I managed to get it out without damage once I could get at it with the radiator off.

But I did the valve clearances while I was going and found all exhaust valves were at .008inch (just in spec) but the inlets were all over the place. One at .006, one at .004, three at .003, two at .002 and one I could not get a feeler under.

I never had a problem with the chain just wanting to jump unless I was turning the engine over by hand with the tensioner off. It is easy enuf to put the cams back in the right spot if you get them out. I was able to get the inlet cam out by removing the tensioner and the guide at the front of the engine, lifting the chain off the sprocket and taking the cam out sideways.

 

Is it possible to do it without taking off the carbs ect?

 

I've never removed my cam chain tensioner with the carbs on however with my 3LN it certainly looks like it would be possible without too much effort. There is a decent gap on either side of the bike to look in while moving a spanner & there looks to be more then enough room to pull the tensioner out. Just pull your right hand side fairing off (less fuel pipes and junk in the way on this side) and take a look in at the tensioner (you'll see it in the middle of the engine directly below the carbs). See if you can comfortably access all 3 bolts with a spanner/socket set. If so then go ahead and pull it out.

Here's a pic I just took of my bike from looking in the gap on the RHS at the tensioner.

If you're working on an older model bike without a deltabox frame then I have no idea how easy it is to gain access without removing the carbies.

 

Thanks ill have a look into it.. mine is the deltabox frame a 3ln3 I think

 

If you remove the tank it should make it a lot easier to gain access.

 

Yes I was actually thinking about that

Sorry if its a stupid question but what exactly adjusts the tensioner?

is it the big bolt? or the 2 smaller ones.. im not sure

 

The picture I posted is from an 3LN3 so yours should be the same.

This is an automatic cam chain tensioner, you can't actually adjust it, only check & replace it. The big bolt has 2 springs under it which work the tensioner and the 2 small bolts on either side just bolt the tesnioner to the engine. The process above describes how to remove the tensioner & check if the tensioner or cam chain is in need or replacement.

 

oh ok... thanks for that

 

Just out of interests, how do u tell if the automatic cam chain tensioner needs chaining? Im guessing the cam chain is checked on the amount of slack present.

 

To be honest I don't really think you have to worry about the tensioner wearing out on these bikes. Unless it somehow seizes up or the ratchet starts slipping allowing the arm to be pushed back (both of which are unlikely) I can't really see what else could go wrong.

The main reason to remove the cam chain tensioner via the process Boz described above is to see how much adjustment it has left. If the tensioner is almost at the end of it's adjustment (all the way out) then that's a good indicator your cam chain is worn/stretched and it's time for a new one.

 

The idea is that if you undo the big nut first and remove the springs, the tensioner will sit in the position that it was running in the engine. When you remove the tensioner body, the ratchet assembly will still be maintaining that position. It is just a matter of checking how much adjustment is left on the ratchet by pulling the tensioner arm out the rest of the way through the ratchet.

Lift the ratchet latch on the tensioner arm, push it all the way back in and bolt it back into the crankcase and then put the springs in and do up the big nut. The springs will put the tensioner arm back in the correct position.

 

well I finally got around to checking it and its still fine.. and the chain is fine too.. I think it must have been jammed or something because now when aI put it back together that clicking sound has disappeared

 

okay i realise this is an old post, but

so this made me think is it possible that it could all be jammed? even though is should get lubricated by engine oil, and if it is possible then a good clean should free all the parts and allow the tensioner to do its job?

 

It would be worth pulling the tensioner out and checking it and see if it fixes the problem.

 

Hi i need a little bit of advice. I bought a new tensioner because my old one was jamming, and want to replace the old one tomorow. I plan to remove the tank and airbox and just swap the tensioner over. is it ok to simply do that or wil more engine surgery be needed? ie cylinder head remains on? also do I have to adjust valve timing?

Thanks and I hope its easy because im pumped to get rid of that cam chain sound.

Also I will recieve a new gasket but i don't want to use it untill i do the valve adjustment in a couple of months, as I believe the tensioner has to come out again anyway. So should I be using some gasket sealer product for now?

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My recollection is that you need to do neither. I am sure it can be accessed from the side of the bike. Just make sure that you follow the procedure and remove the spring and retract the mechanism before installing. The spring and capnut is the last thing you put in once the tensioner is in place.

As for gasket just use the new one. It will survive a few on and offs.