Yamaha TRX850 Enthusiasts Forum

So, I have been a bit quiet around here lately as I have had the bike off the road due to wear on an inlet journal, presumably from oil starvation or a blockage, which was discovered when checking my clearances. Anyway, I have the top end back together and want to order the oil pumps from the USA as they are MUCH cheaper when buying matching parts for a '92 TDM850. The scavenge pump has the same part no., but the engine pump has has a different model prefix, ie:

TRX850 oil pump assy. 2 = 4NX-13303-00
TDM850 oil pump assy. 2 = 3LD-13303-00-00

Now, I am not fussed about the last two digits, but the model prefix bothers me. The gears on the pumps have the same part no., but the pump covers are also slightly different:

TRX850 = 3VD-15416-10
TDM850 = 3VD-15416-00-00

... which makes me suspect that there might be a slight difference in fit.

If anyone has experience regarding interchangeability, I would love to hear from you!

I posted up an article on Yamaha part number breakdowns not long ago :

http://www.trx850.com/phpBB_forum/viewt ... 48&p=71974

& Kayla is also a wealth of information.

Are you ordering your parts from partshark.com? I used them & I think I sourced parts from a 1993 TDM.

Thanks for the link MV, I found another topic on the web somewhere regarding Yamaha part numbers and if the 5-digit no. matches, it still seems completely arbitrary if it is the same part or not. That link helped shed some light on the issue, but I'm still not sure whether or not the part (engine oil pump assembly 2) can be used.

Yes, I am ordering from PartShark, thanks to Rob for posting this site - wish I knew about it when I was doing my valves! But it still saved me a bunch when I was getting a camchain and assorted gaskets. My current grief is that post rebuild I do not get an oil weep from the gallery bolt. I have removed the sump and there was a bit of crap in the strainer, but not heaps. The engine oil pump wasn't within spec but was still within "service limit", reckon I should just get a new one but am hoping I can use the TDM one at about a third of the price. Interestingly, the TDM900 uses the same part no.

My plan is to remove the all oil hoses and give them a good blast of air in case any crap is in them, don't want to drop the motor so can't check the tank. Hope pressure can be restored with new oil pumps and it's not cam journal clearances. Might put out a feeler in the wanted section.

JL wrote:So, I have been a bit quiet around here lately as I have had the bike off the road due to wear on an inlet journal, presumably from oil starvation or a blockage

Are you sure it's an oil pressure issue? When I replaced my engine, I checked all the clearances, one only was well out, either I measured it wrong or it closed up very quickly, result was zero clearance on that valve & damage to the cam journal... I have seen reports of other cases, some on here.

Pretty sure I should replace the pumps - didn't get a weep from the gallery bolt after a minute... They have over 100,000 on them anyway, thought it can't hurt to replace them!

Hi JL

Check inside the oil tank. There is a coarse filter there that can get blocked. I know because I had the exact same problem and oil starvation cost me an engine.

It's a carbs off job but worth it to save an engine.

Cheers, Andy.

andyaber wrote:Hi JL

Check inside the oil tank. There is a coarse filter there that can get blocked. I know because I had the exact same problem and oil starvation cost me an engine.

It's a carbs off job but worth it to save an engine.

Cheers, Andy.

Hi Andy, were you able to remove the oil tank cover with the engine in frame? I have searched and can't find any reference to anyone doing this. If it's just carbs off then that would be great!

JL wrote:Hi Andy, were you able to remove the oil tank cover with the engine in frame? I have searched and can't find any reference to anyone doing this. If it's just carbs off then that would be great!

It's possible, at least the top half, but it is a struggle in patience. I couldn't get a proper gasket for the oil tank when I replaced my engine, so I made one out of gasket paper.

That would have been fine if I'd remembered to cut out the sump breather hole in the gasket Ended up building up enough pressure in the oil tank to blow out the sightglass window, good times!

MV - I can remember that happening to you! I will order the gaskets from partshark, assuming it's the same gasket after I check part #s. Also glad to hear the cover can be removed with engine in frame. Is the strainer in the tank accessible with only removing the cover? It's not referenced anywhere in the parts manual, at least from what I can see.

In terms of patience, I have built up practice learning how to remove/install the carbs on the xs650!

I made some gasket templetes up for all the casings and the top and bottom of the oil tank. I can scan them and put them in a pdf which you can pint and use to cut your own if you like, hell of a lot cheaper than buying ready made ones

Con Rod wrote:I made some gasket templetes up for all the casings and the top and bottom of the oil tank. I can scan them and put them in a pdf which you can pint and use to cut your own if you like, hell of a lot cheaper than buying ready made ones

Thanks for the offer, I reckon they might be worth putting in the downloads section! The gasket is $6.98 at PartShark, which isn't too bad though. No idea what it would cost here, probably $20!

Hi JL

My engine was already out of the bike when I did mine, but when I explained the problem to my local mechanic, he said he had come across it before and had to remove the carbs.

Cheers, Andy.

JL wrote:Is the strainer in the tank accessible with only removing the cover? It's not referenced anywhere in the parts manual, at least from what I can see.

Yes. It also unbolts with the oil line (it's attached to the end of the line) on the back of the tank. But I think the frame fouls it so you can't remove it (the oil line & filter) with the engine in situ.

I'm going to have to drop the engine. The bolt that holds down the guide for the vacuum + fuel hoses cannot be pulled out as it fouls the frame. It was also the hardest bolt to undo and the shank appears to have rusted. I suspect the small gap created by holding down the guide allows water ingress. Anyway, I can say in my experience that the oil tank cover cannot be removed while the engine is in the frame!

When I get around to dropping the motor, I'll take some pics of the oil tank internals and strainer as there don't seem to be any here on the site.

Btw, the oil pump assembly 4NX-13303-00 (engine feed) costs $215 here in Oz, double that of the scavenge pump when ordering from the 'states. At least I can order the rest from the US. Fun times.

I'm off for a shower and a beer. It's funny how much those garage floodlights make you sweat when working on the bike.