Yamaha TRX850 Enthusiasts Forum

Hi everyone, hoping someone has experienced this before and may provide a clue.
My bike has developed a rattle (probably) in the engine at about 2800RPM then it goes away at 3000. It rattles louder when under load, you can just hear it if you very lightly revit through that range. It is hard to pinpoint where it is coming from when on the move. Doesn't do it when freely revved while bike is parked. Is it my camchain?? Thanks Gary

Does sound like it could be your cam chain Gary. You can release the cam chain tensioner until it clicks and then tighten it back up again to see if that quietens it up a bit. How many k's on the bike?

Hi Gary,
is the same noise there in different gears?
-trying to separate a clutch/gearbox issue from a motor issue, no rattle while free revving tends to point away from the power production area.

She's got 90000km on the engine. I have had the bike for the last 5000 but from the talk I had with the previous owner when I bought it I am pretty sure they were hard k's. The noise is there in all gears. 3000 rpm seems the ideal cruise around town revs so the noise is regular. I know its a good move to do the camchain sooner than later, but I'm waiting to try to pick up a second hand head to reco as the engines smokey (not too bad but noticable) at high RPM when trying to keep in front of my mates in the hills around here. I'll do the head and camchain all at the same time (unless I come across a lower k engine at the right price) . I'd like to think of the TRX as a long term bike as I've really taken to its characteristics. It handles Ok, it's fun to ride and sounds great. I had it tuned and dynoed a while back and it's doing 73 rwhp woo hoo! I put in a R6 shock and that taught me what rear suspension should feel like (previous bike TL1000S). I think I will have a play with the tensioner and see what happens....

Forgot to add it's always had a very slight shudder on take off in first which I thought was due to the tall gearing, I hadn't considered the clutch as a possible source (until reading the last post.......)

sorry mate, sounds like a big end, worn piston or main bearing. They all tend toward more of a clunky sound than a rattle though. Little end (bearing, of the conrod) and valve train noises tend to go away when loaded up.
If its the former you should be able to hear the same sound at all times albiet quieter, like idle.
Put the sharp end of a screwdriver against the side of the motor in a few spots when its running, put the blunt end against your ear, now the screwdriver is a stethascope. Can you hear it better? Can you pinpoint the area on the motor its coming from? the noise WILL sound different throught the screwdriverscope but try to chase it
1- put it in first, engine off and rock it about - can you hear the same noise?
2- Do a surgical examination of your oil filter and the oil in the filter housing. You will make a mess, try to find some metal color or tiny metal fragments in there.

tell us what you find

Also, dont trust what I write, I cant even find a blatant misfire!


good luck

Years ago I had a Ducati 860 which did the big end, so I know for sure it ain't a big end. I read on another string in here about a guy who found it was the front blinker rattling, not that either! I know the knock of a little end well (XR500, DR250 and other dirt bikes....) As far as the cam chain (or tensioner) I have had the tensioner bolt out, saw the springs, then put it back together - what is the click that was mentioned - is the cam chain tensioner on a ratchet that should tighten when I reinsert the springs? Or should I have pushed the tensioner to click tighter with a narrow drift or something. The rattle does not sound like the beginning of something catastrophic (famous last words) its just a rattle at the very vibraty part of the rev range. When I road it today it seemed to be coming from the clutch/camchain tensioner area. Off to the mechanic for an opinion I suppose......

How'd that ride day go up north this week??

Mine had a rattle at approx same rev range, turned out to be the front indicators rattling in the fairing. You can put some duct tape across them to temporarily hold them firmer for testing. I put some silicone from the back and problem solved.
Also look for anything else loose on the fairing.

Kevtrx849 wrote:Does sound like it could be your cam chain Gary. You can release the cam chain tensioner until it clicks and then tighten it back up again to see if that quietens it up a bit. How many k's on the bike?

Don't ferchrissakes release the tensioner unless it's at TDC firing on the left (astride the bike) - the chain might jump otherwise!