Yamaha TRX850 Enthusiasts Forum

Ive now been keeping a more careful eye on my oil consumption , its getting though about 200ml in about 200 miles (which is about 200ml more than my R1) so am i right in thinking that its rings / valve stem seals ? now do you do a rebore or a hone ? cost is not a problem, but i do want it to last as i will be keeping trixy for some time i think,,strange thing is there is no smoke, ever ,and no leaks from the seal behind the sprocket , so dont know were its going to , will a rebore and new seals fix this ? or is this a trx thing and they just burn oil ???

mine goes thru 1L per 1000miles, so same as yours
but it does smoke noticeably when started, especially when its been stood for a week or more
seems to use less on long journeys therefore i assume its just thirsty when cold

it doesnt bother me much, as i dont do a lot of miles on trixy
thats what the TeDiuM & S10 are for

I'm told mine smells oily from behind. Answer is I dunno. Will a rebore improve it any? For how long? What mileage is on the motor? Perhaps a hone and rings would be the better option?

New rings and a piston hone may sort but you could be loosing oil from any number of places - past the valves?

The problem is that you probably will not know unless you do it!

thanks for all your input ,,Ive have just pulled the sprocket off the shaft and the cover plate and there is some clean oil in there ,,not lots but its a start ,it wasnt there when i changed the chain and sprockets so its only just started to leak Ive had a look at the seal and there are marks but they are not at the 12/3/6/9/ o,clock but its a start i will order the part Monday and see how it goes from there

you'll see pegs on the back of the seal. these go at 12, 3, 6, 9 o'clock with refernece to the crankcase joint. have a look with the seal out and you'll see the oilways which must not be blocked by the pegs.

if the seal has no pegs on the back, don't fit it. (wemoto sent me the wrong one for starters).

thank for the heads up i will get the part from yamaha dealer,(i just hope ive got enough fooking money )

£7.70 from wemoto, plus post. genuine yam part (correct one eventually!)

it will be interesting to see how much it was losing from this seal ,,i will keep you all updated

a common oil loss spot is valve stem seals. When the bike is at rest, oil in the head dribbles down the stems and rests on the valve heads.. So when you start it up, it blows a puff of smoke out the exhaust and will have a oily smell to it while running as its very slow burning.

Since TRX has 5 valves compared to 4, it does leak more oil than usual.

Hone is all you need, you dont need a rebore unless your going bigger in CC, thus need new pistons. A hone is to mearly make sure the cylinder walls are straight, and not wavey. New rings and hone should make a noticable difference. Clean your pistons while your at it.

thanks quan time, when i fit new rings would you gap them as per the book or a bit tight ,is there a better oil control ring that i could use ?

When I put in new rings, it was as book

rings DEF by the book.

The oil wiper / trapper seal is a bit different. Its the big wavey one in the middle of the ring set. This traps oil in its grooves to help lube the piston going up and down. Now here you CAN do a little bit of tweaking if you wish.
Put your wiper seal onto your piston, not the other rings, put the piston into the bore, so the top of the piston is level with the top of the head. It should hold there under its own force. Put a paper clip or something else which is fairly light, count how many you put on before it starts to move. Repeat on both sides.

it SHOULD be around 25g i THINK, but id double check that (depends on engines, but id say 25g is being conservative) Take your oil ring off and lightly close one of the waves up a little, it shouldnt require much at all. Re measure. Squeezing the wave together will make less friction, pulling it apart / flattening them out will make it hold into the bore more.

Please note: this is going to extremes, and 99.9% of bikes dont need this. But since you have the pistons out and getting new rings, why the hell not.

Once you have bent one of the waves, dont rebend it. Go to the next one. And also remember you only need to do the TINYEST amount to get a difference. Will take time, but you can be happy knowing you did a good job.

PS: random double spaces for free, stoopid keyboard is dying.

thanks for all the info i will be looking in there soon , iam going to change the oilseal behind the sprocket to see if that inproves things first ,then my plan is a topend rebuild at the end of the season ,,so iam sure i will have more questons then ,,,,thanks