Yamaha TRX850 Enthusiasts Forum

first of all i'm a newbie so hi guys .
i'm new to the trx and i've had mine for about 3 months and read all the write ups on them before i bought 1 and i'm well impressed with it.
it's a p reg but it's got 35,000 miles the clock and everywhere i looked said about keeping your eye on the oil level cause they do burn oil but mine seems to be eating alot of oil.it's used half a litre over 180 miles,just after a bit of advice as to what the problem could be and what sort of fix it is,chers for any help .
heres the trx and below that is my 2-stroke fettish that i'm haveing at the moment,a project i've just finished and there's more of em to come .

Hello and welcome.

High oil consumption could be caused by stretched valves - oil passes by the valves stem seals, or worn rings or possibly by the output shaft oil seal weeping.

tbh it's most likely valve stem seals.

Some people find certain oils better than others - my opinion is not to run a fully sunthetic oil as that seems to get consumed faster.

Check the underside of the engine for a film of oil - this will be the output shaft seal. There can be a problem if this is fitted incorrectly. It has four prongs on the back which must not cover the oilways in the seal housing. The prongs need to be at 12, 3, 6 and 9 o'clock. The oilways are at 7 and 11 o'clock.

Just be sure that you're checking the level correctly - after a 15-20 minute minimum ride and let the oil settle for 10 minutes before checking, with the bike held upright, engine off.

Nice looking TRX - best standard colours.

Amazing. I was about to post a message of my own about oil consumption! Mine is a 1996 model with 38000 kilometres.
Last weekend I went out on a 200 mile trip and took 300mls to fill it back to the level I left with.
So my consumption is about half a litre every 350 miles, which concerns me, but about twice as good as yours!

There does seem to be a well documented problem with pre-1997 TRXs stretching their valves, eventually causing the cylinder head to trash itself

I have already changed the oil shaft seal but it has made no difference to oil consumption.

My debate is whether to just change inlet valves / oil seals or whether to also renew the piston rings.

And similar to you, I have an unrestored 1981 Yamaha RD350LC ! Quite a few on this site appear to have a fondness for Yamaha Strokers....

I'm sure a dash of T-cut will bring it up just fine

thats for the reply martin,their is'nt any oil under the engine so most likely the valves by the sound of that.is this a easy job for a novice mechanic as i've never pulled a 4-stroke motor to piece's or is it a job for a proper mechanic .

kebab;if thats matchin numbers it's worth afew quid already,i've got a nice standard swingarm if you fancy a swap i've got a 350 lc to do aswell but will probably never get done,to many projects at the mo.
i've fitted the later ypvs f2 engine,forks(drop straight in)wheels and swingarm to the blue 1,needed some mods to the frame to take the swingarm and shock tho.

scottie it's a head off job.

disassemble, measure valve stems, replace valves as required, fit new seals, reassemble, check clearances, re-shim, prime oil to head.

it's do-able, but not as simple as a 2 stroke, obviously

martin young wrote:scottie it's a head off job.

disassemble, measure valve stems, replace valves as required, fit new seals, reassemble, check clearances, re-shim, prime oil to head.

it's do-able, but not as simple as a 2 stroke, obviously

tahnks m8

Scottie

first of all welcome

2nd - that RD is lovely. Don't think I've ever seen a powervalve engine that clean Do you wanna come round and rebuild my TDR

3rd of all - what the guys have saidabove is right. Either valve seals or rings (or probably both). Nothing major in terms of works if you are a competent mechanic.

BTW - you can download the Yamaha workshop manual from this site.

phuk72,thanks for the comment on the rd,if u think thats clean u wanna see some of em on the rd forum .
sorry to the other lads for the 2 stroke piccy's but it is a twin after all .
as for the trx,i might av a go at it over the winter,

cheers guys

I have a 2 stroke single as well!

Dave E

Maybe we should start a 2-stroke corner

I just read the other day that the valve part number changed in 1998 (see here) which would explain the problems I had with mine.

It was burning well over 1L per 1000km before the engine doctors had their way with it.

So......replacement of all the Inlet valves AND replacing the valve guide oil seals should slow down oil consumption considerably?

Or would it be wise to also replace the piston rings / hone the bore?


I dont expect to ever have zero oil consumption, but I also dont want to keep topping it up like a two-stroke!

well i did read alot of write ups on the trx before i bought it,because to be honest i had never heard of them untill some1 on the rd forum posted up a piccy of his and i just loved the look of em.and i still have'nt seen another 1 on the road yet but me brother liked it that much he had to buy 1 aswell and his does'nt use the slightest drop.

i did expect to top up the oil now and again but not as much as this so it needs to be done or it will cost me a fortune in oil but not sure whats gunna be involed,it will be setting it all up that will be a pain for me .
cheers guys now i know what the problem is i can do sommat about it and might aswell changed the rings and get the barrels honed aswell while it's all apart

kebab19 wrote:So......replacement of all the Inlet valves AND replacing the valve guide oil seals should slow down oil consumption considerably?

Or would it be wise to also replace the piston rings / hone the bore?

I did all that to mine - it was an expensive fix but she runs sweet now.