Yamaha TRX850 Enthusiasts Forum

(Photos: cylinders on left, gearbox on right, taken from left side of bike)



Got a leak, behind the cylinders, in front of the gearbox. You can see the oil pooling around the bolt for the casing, bottom left in the second pic.

The external oilway is covered in oil, as is the base of the gearbox but the cylinders seem fine, so I was thinking the rose joint/bolt where the external oilway goes into the engine, but this is as tight as it can be. So what else?


Does this connection have copper or similar washers which could have gone? (looks like it in the pic)
Base gasket for the gearbox?
External oilway cracked? (never heard of it but..?)
Anything else?


What are my options for finding out? I'm thinking tank off, airbox off, clean it all and run the bike to see whats weeping and from where?

Cheers

Dave.

Ok,first of all a degreaser and wash off,don`t run the bike just use an old paintbrush for the degreaser and something like a washing up liquid bottle filled with water to forcefully wash off the oil contamination.
I`m doubtful it`ll be the externall oil pipe that`s split,never known a mild steel oil pipe to go,although any flexible sections are weak points obviously.
It could be the banjo come loose but again it`s not very common.It could also be a stress crack on the cases,again VERY rare but I`ve seen it at oil gallery banjo`s before.
I`m guessing it`ll be the oil tank gasket(underneath the oil tank)loose filler cap,or maybe even the breather hose from the cam cover(split/perished).
A good way to find a slight/slow leak is some talcum powder around the dried engine,oil will show very quickly on it,just run the bike up to temperature on tickover and keep watching.

Or the breather pipe at the camcover kinked/blocked causing crankcase pressure to build up and pee out oil and mist.

It's not as simple as "someone" having missed the hole when filling oil?

If not, then the other recommendations before me could have been mine as well... Gaskets/washers for the valvecover, oilpipe, oiltank, breather. Can't remember how the airbox looks like, but if there's oil in it, I recall it has a hole for letting oil out?

HansJ wrote:It's not as simple as "someone" having missed the hole when filling oil?

If not, then the other recommendations before me could have been mine as well... Gaskets/washers for the valvecover, oilpipe, oiltank, breather. Can't remember how the airbox looks like, but if there's oil in it, I recall it has a hole for letting oil out?

Yeah, that would be my first thing to check - if you spill oil while filling (overfill or miss the filler) it will end up where it is in the pic. Clean it, then run it and see if you get fresh contamination.

Don't think its an oil spill as I've not topped up for a while and the oil on the motor is definitely fresh.

I've checked the crank breather and the drainhole from the airbox and its not that.

Just seems odd that the 'oiliest' bit is the external pipe. Makes me think it is coming from above that.

Maybe I should be looking at the right side of the bike around the oil filler pipe area. The oil on the bike is on the left side but that may be because thats the way it leans on the sidestand.

Think a partial stripdown, thorough clean and a run with it on the paddock stand is in order, and hope its nowt too major!!

trixynut wrote:Don't think its an oil spill as I've not topped up for a while and the oil on the motor is definitely fresh.

I've checked the crank breather and the drainhole from the airbox and its not that.

Just seems odd that the 'oiliest' bit is the external pipe. Makes me think it is coming from above that.

Maybe I should be looking at the right side of the bike around the oil filler pipe area. The oil on the bike is on the left side but that may be because thats the way it leans on the sidestand.

Think a partial stripdown, thorough clean and a run with it on the paddock stand is in order, and hope its nowt too major!!

DOH!

Well, hopefully it's something you DON'T have to drop the motor to fix.

New copper 'O' ring at the bottom of the banjo? thats where it looks to have been weeping.

Dave E

Sherlock had a similar problem on his Diversion at Walcha IIRC, I just cannot remember what the fix was.
You there Scott?.

the trick with copper is get it cheery red with heat then drop in cold water ,,hey presto new soft copper washer ,,, we used to do this with triumph head gaskets

`Annealing` is the technical term Steve,it`s used to make the copper more ductile.
Quenching isn`t necessary,in fact it`s better to heat the copper to `dull red` then let it cool naturally.
And yes,unless copper`s badly deformed/compressed it`s always reuseable.
By the way,similarly you can soften/anneal aluminium the same way but to guage the correct heat a wee bit of washing up liquid can be used,this will boil off and the aluminium will blacken,this is the point to take away the heat source and allow the worked piece to cool.

i just rub a bar of soap on aluminium and when it turns black,,,, bingo bango,,, same thing really

..ok, so sprayed with degreaser, cleaned thoroughly, dried, and went out for a blast.

Got back, and the investigation has turned to the right side of the bike..

..there's oil on the main external oilway from the oil tank to the right front of the engine (the 'shiny pipe') and some spots above this on the end of an overflow pipe but as its from the carbs, its not that. So working upwards from there, theres no oil coming out from any of the gaskets on the oil tank (bottom one or middle one) and no oil on the small diameter external oilway that runs from one side to the other at the back of the cylinders, but there is oil on the oil filler pipe.

So, I'm pretty sure I've worked out what it is ................................. but I'm not saying!!

.. but theres a clue in the photo!!

Split filler cap O ring?
Sorry I cannot view those images at this pc.

there's no cap ... or am I being blonde (again!)