TRX850 Oil return problem?

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

Ive got a yamaha trx850 (same as tdm850 engine). I've recetly had it apart due to a few problems and having reassembled it im still having the same problem i had prior.

Basically, the window in the sump wont indicate any oil even though ive filled with the specified amount and circulated throughout the bike.

The bike runs a dry sump with the oil stored above the engine, there are two oil pumps one for the engine and one to return oil to the sump. The return pump is certainly pumping oil having disconnected the return hose whilst running the bike but its just not coming up in the window apart from when i initially filled the bike with oil.

I have replaced the oil pump, bled the engine as presribed in mr haynes, but still, no oil seems to be coming through to the window.

Any ideas? im stumped!
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

I have no experience of thew TRX but I've had dry sump Yamahas before (XTZ motor in my MZ)

First and most obvious possability is that you haven't put enough in there. Filling the oil tank after fully draining the engine just fills the oil tank. As soon as you start it, that oil will be sucked out and start filling up the rest of the engine. I'd expect a good 3-400ml to be inside the various oilways, filter chambers and engine componants so you're going to have to top it up once it's been run and bled after a service.

They are a bit odd to check the oil level in anyway. Most dry sump motors I know require you to run the engine at idle for about 30 seconds with the bike totally upright to allow the return pump to do its business then kill the engine. Wait a minute or so, then check the level. If you check after revving/running, the feed pump may have chucked a load of oil out there but the return pump may not have put it back again yet.

If the return pump is returning oil, the feed pump must be feeding it or there would be nothing to return. So your pump is working.

The bit you are filling with oil is not the sump. As the term "dry sump" suggests, the sump is not normally full of oil, it's fed into the bearings by the oil pump then sucked out again. Your oil could potentially be dropping into the sump and staying there in which case it would smoke on startup and probably start breathing a load of oil out through the crankcase breather. If there is a seperate sump drain plug, you could try undoing this, a fairly small amount of oil should come out (I doubt any more than 100ml).

I'd also say the following. If there is enough oil in it, if the oil is disappearing from the oil tank (look with a torch as you start it) and reappearing down the return hose and the oil pressure light is going out, there can't be much wrong with it. Oil doesn't just disappear.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

temeluchus · World Chat Champion Joined: 01 Oct 2008 Karma :

As I recall, on my XBR500, there should be a one way valve on the return to the oil tank. If this goes the oil will drain back into the sump so the tank will always seem to be low. Does make it smoke a bit when started cold.
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Some shite cruiser. Now with guns and FREEDOM!

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

cheers lads, firstly i dont think there is a one way valve on the TRX engine but ill double check that.

Furthermore there is no oil burning on startup and the plugs are as they should be.

i've filled with 4000ml of oil where a dry engine should only need about 3800 if i remember rightly, alas no oil is showing and ive overfilled to the point of it spewing out of the overflow because of this problem in the past (thus how i discovered the problem!)

i was thinking perhaps the oil is staying in the sump rather than the oil tank (cheers stinkwheel, wrong terms being used!)

I will try letting the bike idle for 30seconds without any revving and see if it works, but i'm tempting to lift the tank cover off and see whats happening in there.

Thom
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

temeluchus · World Chat Champion Joined: 01 Oct 2008 Karma :

According to the fiche, the non return valve is in the oil pump itself. It is a small ball bearing on a spring. If its stuck you will never get the tank to fill.
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Some shite cruiser. Now with guns and FREEDOM!

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

Hi, is this the trx pump or the xbr we're on about now? ive had the oil return pump apart and there is certainly no spring/bearing inside it?
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

temeluchus · World Chat Champion Joined: 01 Oct 2008 Karma :

evoboy · World Chat Champion Joined: 20 Aug 2009 Karma :

Cant really help with the problem.

But my TRX oil tank always shows oil in the sight glass.

I was told to get the bike hot then check the oil level?
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Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

APT Motorcycles

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

cheers lads, when i got the bike before stripping it down it also showed oil in the sightglass but it remained dry for a few months so perhaps a seal dried out or something. i'm looking into this one way valve thing as this would explain why the tank isnt filling with oil.
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Just thinking out loud here.

Could the oil pressure relief valve in the sump be stuck open?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

god i hope not. I've just reassembled it all.

I did notice this item in the fiche, im not quite sure of its function, but i guess it opens under excessive pressure to release it?

I cant imagine wy or how it would have opened, nevermind gotten stuck?
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

temeluchus · World Chat Champion Joined: 01 Oct 2008 Karma :

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

hey mate, do you mean the pressure relief valve? i think ive seen the diagram you mean
____________________
Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

My god! a bike with 28k miles has obviously NEVER had its sump opened. The strainer had about 10-5% of its surface area blocked with shite much of it metallic!

It works now that its clean and hopefully thats the end of my problems. Cheers guys.
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

evoboy · World Chat Champion Joined: 20 Aug 2009 Karma :

Thom · World Chat Champion Joined: 24 Oct 2007 Karma :

I'd certainly be tempted to look at it even just as a precaution, i wouldnt like to think of what could happen if i ran my bike as it was for long!
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)