Upgraded cam chain tensioner

[drix]

Hi guys

My bike has a bit if cam chain rattle, it starts on the button but sometimes pop & it doesn't run tip top low down in the revs despite the carbs being balanced correctly (near to new FCRs). My mechanics believes it's the cam chain tensioner wearing out and suggested a replacement... What should I go for? Standard Yamaha part or aftermarket or the below which is Yamaha but from another model/type?!

A light "rustling" noise which comes and goes. The modified tensioner came out in 2005 or 06. The new one has a longer supporting body inside the camchain tunnel - I think they're identical from the outside. It's an R6 type of tensioner on a coil spring, not the ratchet type of the 850

The bike has 44000kms on the clocks, valve clearance not done but no valve noise or valves closing up symptoms to be noticed.

Cheers
Adrien

[alextrx850]

44,000 ks seems a bit young for the tensioner to be a problem Adrian.
Maybe test the theory by loosening the two bolts on the tensioner and slide the unit out ten mm.
Maybe give it a tap as well, then refit.....tends to wake it up.

[cobbadiggabuddyblooo]

The TDM 900's had a few issues early on with their cam chain tensioners but I've never heard this from a TRX??
They work via a ratchet set up so once extended they lock and the only physical way to release it is to unbolt the tensioner and remove it .
Then when in your hand you can release the ratchet (there are teeth on the shaft) that locks the rod so you may push the rod back in.
The larger retaining bolt on the outside of the tensioner hold the two springs that keep tension on the rod upon the chain.

Easy job to check, remove the larger retaining nut and springs.
Unbolt the tensioner but mark the top of the tensioner with a black dot next to the top retaining bolt.
The correct way for it to sit is,
There are two vertical supports that run from the top and bottom retaining bolt with the spring retaining nut in between.
The shorter vertical support should be on top, this is so the ratchet on the shaft has constant pressure upon it with the rotation of the chain which will be rising against it.

Count how many teeth are out... Write it down as a reference so you can count them when refitting.
Now with the tensioner in your hand, unlock the ratchet and examine the teeth on the shaft.
I have 2 with over 140,000km's on them with no visual wear upon the teeth or the pivoting lock.

When bolting back in place, unlock and push the shaft all the way in , bolt back in place then place a small screwdriver in where the springs go and push the shaft out slowly and count the clicks until it stops. (around 8 )
Apply a little pressure but no need to be excessive to see if the shaft is firmly seated and no more clicks.
Replace the springs and larger nut.

The clutches can be a bit rattly on the trx, pull in the lever while in neutral and you can hear the difference.

[dandywarhol]

My post was about the 900 tensioner - it won't fit the 850. How do you know the clearances aren't tight - if tight you can't detect it by noise - the opposite in fact. I'd check the clearances - I did and found 4 inlets had minus zero clearance! And it popped when starting up and ran rough at idle

[cobbadiggabuddyblooo]

Yes I agree Dandy, personally I would look into general inspection, maintainence and clearances possibilities to start.
Doesn't take long to check electrical and earth connections, carby and float levels, vaccum lines, jet needles and emulsion tubes ( needle jets )
44,000km is close to a a major service , you would be changing brake and radiator fluids so just remove the radiator and check your valve clearances.

[drix]

I'll have a go at fettling with the tensioner this weekend. Also have a spare motor for donor parts. Failing that, then yes, valve clearance checks it is!

[dandywarhol]

My suggestion would be to revert back to stock carbs and give me your FCRs

[cobbadiggabuddyblooo]

Just be mindful their may be tension on the cams in their position due to the valve springs.
If looking at checking your valve clearance , it may be worth your while to check the tensioner then as you can make sure the cams don't move and are still aligned correctly when releasing pressure off the chain.

[drix]

Finally got round to playing with the second cam chain tensioner and checked a few other things. Only thing I noticed was a slight air gap from one inlet rubber which I still need to fully address but all in all, symptoms more or less remain.

A good excuse to open the top end this winter for some head porting, kent cams and fit the 2mm valves that have been sitting at home for a while!