Yamaha TRX850 Enthusiasts Forum

I really love my TRX...

but I just can't hack the oil consumption. Even my 27yo Pantah consumes nothing like this beast does. It's a 1999 model with 'only' 40,000ks on it which I wouldn't have thought was much at all!

I've done some topic searching along these lines and even tried Diesel oil, but I guess it's time for valve stem seals and rings. Is it a big job to get done? Can I, a reasonably competent DIYer have a bash at it, farming out any machining jobs to the pros, or is it something I shouldn't even consider tackling at all? What else would I be prudent to change whilst I have the engine apart, given that I don't need any more performance?

I'd like to keep this bike for a while, I love riding it, but I've got to get this sorted.

Thoughts? Suggestions?

Generally accepted in TDM circles it's a ring/bore issue. Worn valve stem seals are usually diagnosed as puffs of smoke on startup or on the overrun.

It's my belief that too gentle running - in causes the problem, the rings and bores glaze through too gentle load during the critical first 1000 or so miles. There's rarely blue smoke showing under hard acceleration but if travelling close behind you can smell burning oil.

Usually no appreciable wear on the bores so a hone and set of rings sort it out.

My bike uses no oil after changing to semi-synthetic, but I guess thats just a cure for milder oil abuse.

Thanks guys, I've located another engine and will see if I can buy it. Not perfect, but I then have something to overhaul whilst still on the road.

dandywarhol wrote:It's my belief that too gentle running - in causes the problem, the rings and bores glaze through too gentle load during the critical first 1000 or so miles.

This is so often the case DW, you've got to load the engine - over a wide range of conditions. Babying it is of no use whatsoever.

Not guilty of that here, officer.

I've been lucky with the two TRX's I have owned have never used any oil. I am still thinking of doing a full rings, bearings and stem recon in the near future. Might even slip in a 878 kit and 3rd gear set while I am at it.

when i overhauled mine it was clear that the stem seals were past there best they had gone hard ,, just don't be tempted to use pattern stem seals , the ones i had were slightly over size so they never went any were near my engine , with a spare motor you could rebuild in your own time and end up with as good as new motor,,, good luck

Don't forget to check the oil seal behind the front output shaft sprocket.

I'ts a long shot.

I overhauled a mates bike after it destroyed a big end bearing.Did the job properly with all new genuine parts.

Put it back together and it was leaking oil near the starter motor.I pulled the starter out and fitted a new o'ring to it ,only to still have a leak.

Finaly I tracked it to the front sprocket,and I remembered reading that these seals sometimes let go.I replaced it and the leak stopped.

When I removed the sprocket covers,it was obvious that it had been leaking for a long long time.

Like I said it's a long shot,but must be worth a try.

I'm with you on this one Davamb. I'm also in love with my TRX but the oil consumption is quite annoying. I did a piston rings and stem seals job on an other (older) bike (XZ550) and this cured the consumption on that bike. The job itself could be done by a DIY with some experience. I'm thinking of doing this to my bike the upcoming winter.

Mine is one of the rare ones Dave that doesn't use that much at all. It only starts to burn it towards the end of the service interval, which is now. Only topped it up twice in 6,000kms

Bob

Honing and new rings can cure it, but remember to have the cylinder wear checked. The big heavy pistons tend to wear down the bores, and if that's the case, honing and new rings will only cure oil consumption for a shorter while. I don't say it won't cure it, but since ther engine already is in bits and pieces, let a workshop do the measuring of bores and pistons.