Yamaha TRX850 Enthusiasts Forum

I am gonna replace the valve stem seals on my TRX to try and improve the oil consumption issue. My question is...are there any special tools I will require, is there any thing I should be aware of (read careful). I am gonna take the motor out whilst I do it, because I am going to re-paint the front of the motor at the same time its out. I was considering replacing the rings but I am not sure how big a job this is. As always any help or advice is greatfully received. Thanks David.

Kenvis Repesco wrote:I am gonna replace the valve stem seals on my TRX to try and improve the oil consumption issue. My question is...are there any special tools I will require, is there any thing I should be aware of (read careful). I am gonna take the motor out whilst I do it, because I am going to re-paint the front of the motor at the same time its out. I was considering replacing the rings but I am not sure how big a job this is. As always any help or advice is greatfully received. Thanks David.

Well, i think you´ll find out changing rings and hone it will be easier than the seals...but as you in there and want to less the consumtion of oil i would def do the rings. Get a ring compression tool (it also helps with 4 hands)....and then you need a valve compress toolie (left this to others so i never seen one IRL)

I'm with above If the valve seals were shot it would smoke on startup and when you open up after deceleration.

I've yet to see a smoky TRX/TDM but I have followed a few and oil burning can be smelt under aceleration, indicating glazed/worn bores/rings - I go for the glazed problem to be the problem

Agree on the rings verdict, I would still replace the stem seals as well though, they're cheap & it's not much extra work.

My thoughts exactley. Thinking about it...a dealer recently told me the bores on the TRX are plated, maybe Nikasil like on the RGV's etc. Forgive my ignorance, when you say hone, does that mean just cleaning up the bores or actually removing material, thanks again David.

Only TDM 900 bores are ceramic plated - the TRX is plain ol' steel (or maybe it's cast iron). The problem with honing is that you can end up with too much piston/bore clearance - what you want to do is to "glazebust" the bores - a process which scratches the bore surface. Glazing is common with engines which receive too gentle a running in period thereby the rings and bores never properly bed in.

Here's a pic of a glazebuster...................attach the spindle to a drill and run the buster up and down the bores to produce a cross hatching effect which traps the oil to aid bedding in. New piston rings should then be used BUT the bore needs to be thoroughly washed in soapy water to remove any dust or you'll end up with more trouble. Another method I've seen used is to leave the cylinder outside overnight after a rainstorm to produce rust on the bore surface - but I think I prefer the glazebuster.........................

He must be confusing the TDM900 (which has a plated bore) with the TRX which has a reborable cast iron bore.

Thanks so much chaps...really appreciated.

Mine smokes on start up so I'm guessing I need to get the same done to mine
Whats a bike shop gonna sting me for this ?