Yamaha TRX850 Enthusiasts Forum

Hi Team,

Decided it was time to give my rex a birthday last weekend. I got real excited towards the end of the day and whipped the head off to check the clearances.

Good thing I did that.

Found one of my Inlet valves with a 0 clearance. Pulled the cams off to check things further and found even more issues.
My thoughts is that at some stage its suffered oil starvation and the cam has started to chew the head and cam cap. Photos below.

My questions are:
Can I re-use the head? My thoughts were that there is potentially not much load on that face so it might be salvageable?
Will the Cam need to be replaced?
It is possible and if so where can I get new Cam Caps? Im New Zealand based.

And finally as a supplementary question:
With my 0 clearance do I need to check and/or replace that valve?

Its a high milage bike and I know very little about the history. It does not get ridden loads, more of an impulse buy at the time. (As soon as it started up I buckled.....)

Any info would be greatly appreciated.

Cheers

Apparently I cant upload photos. Niggly

Alright hopefully this works.

Flickr photo links below

https://www.flickr.com/gp/157937416@N05/86C919

Caps are matched to the head and not usually an interchangable part. They are more than likely bored to the correct size with the cap fitted.
Cylinder No.1 inlet cam journal is a common gall as it's starved of oil on initial start up. Song of the lads in Germany have placed a small bleed point on the end of the inlet cam oil galley just like you see on the exhaust cam galley.
Check clearance with plastigauge and if possible clean up the surface with a touch of wet n dry.
Cam/journal clearance tollerence is in the workshop manual.
If you got the head off chech your valve seat/head as pre 97 trx/tdm's had issues with inlet valves closing up and need replacing by 60-80,000km. The revised inlet valves fitted on later models will fix this problem