Yamaha TRX850 Enthusiasts Forum

Came to my second valve clearence job, to find all my inlets way small. Removed my inlet cam to find the camshaft eating through the head on number 1 cylinder, not uncommon so it seems. Had to scrape away a metal lip from around and above the shim bucket to remove it. Must admit i had to do this last time i did the shims, and that was at 28000m. But being of limited funds and botch it attitude i persisted with it. Its been on 4 european trips since then. Got a complete second hand head on its way from a 18000m motor. Mine is now on 72000km, about 47000m. Going off posts i have found its an oil feed problem, is there any modification to solve this. Apart from this major hic up its been totally reliable. Must be time for a new bike me thinks.

andre wrote:Came to my second valve clearence job, to find all my inlets way small. Removed my inlet cam to find the camshaft eating through the head on number 1 cylinder, not uncommon so it seems. Had to scrape away a metal lip from around and above the shim bucket to remove it. Must admit i had to do this last time i did the shims, and that was at 28000m. But being of limited funds and botch it attitude i persisted with it. Its been on 4 european trips since then. Got a complete second hand head on its way from a 18000m motor. Mine is now on 72000km, about 47000m. Going off posts i have found its an oil feed problem, is there any modification to solve this. Apart from this major hic up its been totally reliable. Must be time for a new bike me thinks.

Any symptoms in ordinary running, or was it only obvious once you got the head off?

Well its been poor starting in recent weeks, so i suspected valve clearence, and knew it was due. Was maybe noisier at the top end than normal, hard to tell as it will have been a gradual difference. And sounds like a tractor when at its best any way.

Hmmmm,I`m not aware of this `oiling` problem,is it indeed something that rears it`s ugly head all too often members?
And what`s the reason,poor quality oil,oil pathway issues(not direct enough feed etc)or a mish-mash of all three?

Well even the replacement head i got is showing some mild signs of the same thing. So must be a very common problem. At a guess its poor oil feed, always seems to be the inlet side on number 1 cylinder, also the one with the thinnest bearing journals. The replacement came from an 18000m engine, so should'nt have to worry about it for a couple of years.

andre wrote:Well even the replacement head i got is showing some mild signs of the same thing. So must be a very common problem. At a guess its poor oil feed, always seems to be the inlet side on number 1 cylinder, also the one with the thinnest bearing journals. The replacement came from an 18000m engine, so should'nt have to worry about it for a couple of years.

Hmmmm,interesting,there was no evidence of it on mine when I had the cam cover off for repainting two months ago and mine had done just shy of 20,000 miles at that point.
Any other members aware of this?

mine was ok at last inspection 22000 miles the oil comes in on the right hand side inlet cam , i would think its a combination of poor quality oil ,, not been changed enough ,, low level ,, or possibly contamination from fuel mixed in the oil ,, ie emulsion tubes

You cant tell till you take the camshafts off, and then try and remove the middle shim bucket on left side. It may not be that common, i am unlucky alf afterall. Always use decent semi synthetic oil, changed every 4000m. All my valves are lapped in, waiting for gasket set now which includes valve stem seals.

are your stem seals pattern or genuine ??

Its a complete engine gasket set, and its pattern. You are going to tell me yjey are crap now, i bet. The Yam head and barrel and 2 exhaust gaskets cost almost the same. And monet is tight.

Oops just noticed my mistake their. Thats what happens when one does'nt wear ones glasses.

Just had my cams out for a re-shim and there was no visible wear on the head at all and this is on a 30,000 miler

andre wrote:You cant tell till you take the camshafts off, and then try and remove the middle shim bucket on left side. It may not be that common, i am unlucky alf afterall. Always use decent semi synthetic oil, changed every 4000m. All my valves are lapped in, waiting for gasket set now which includes valve stem seals.

I was gonna ask if yours was ok, i seen your previous post. Guess i am just lucky. I see it was the inlets that where out. On my replacement head all the exhaust cams where at or close to the max tolerence, and the right side inlet where all way to small a gap. How much did you pay for the cam chain?

andre wrote:I was gonna ask if yours was ok, i seen your previous post. Guess i am just lucky. I see it was the inlets that where out. On my replacement head all the exhaust cams where at or close to the max tolerence, and the right side inlet where all way to small a gap. How much did you pay for the cam chain?

Cam chain was £43 for an original Yamaha one. My old chain was about 1 1/2 links longer which had put the timing out and had the tensioner on its last notch.

AHTHUD wrote:

andre wrote:I was gonna ask if yours was ok, i seen your previous post. Guess i am just lucky. I see it was the inlets that where out. On my replacement head all the exhaust cams where at or close to the max tolerence, and the right side inlet where all way to small a gap. How much did you pay for the cam chain?

Cam chain was £43 for an original Yamaha one. My old chain was about 1 1/2 links longer which had put the timing out and had the tensioner on its last notch.

The timing is still correct but it looks off as it don´t line up as it would with a new chain, it will begin to get off when camchain tensioner can´t do more...so you where close....