Oil pump and 2nd, 4th gear in my 2000. Please advise.

I finally split my cases yesterday and upon pulling the oil pump out it started dropping pieces of a broken pin and other metal chunks from the opening. Also, the star shaped rotor had grooves cut between it and the area it rests against. I have not yet dissasembled the oil pump assembly itself, but I'm sure the culprit to my scarred cylinder is in there.

The pickup screen is clean as can be, as was my oil filter after the cylinder damage occured. The pieces that caused the damage must be from inside the pump, right? Where does the oil pump deliver oil to... how did it get to my cylinder without damaging anything else along the way?

Also, second gear has some wear on the inside where it meshes with 4th. I never had any shifting problems in the past, but I got a feeling they're coming if I reuse these gears. Are there any more problematic gears I should replace while I'm in there? The shift cam looks good, but the one fork I took out has some wear in it. I am going to replace the forks, but do you think its necessary to replace the shift cam too?


There are two oil pumps on your bike.

The one you are describing is what I would call the (star type) scavenging pump, it pumps oil out of the cases and back into the reservoir.

It does make sense that, since the pickup screen is intact, whatever damaged the pump was part of the pump itself, especially if it looks like it was something too large to get past the screen.

For this same chunk of metal to have caused your cylinder damage, however, it would have had to travel through the oil return line to the oil tank, past the screen in the bottom of the tank, through the (impeller type) pressure pump, through the oil filter, and then into the top or bottom end (the pressure pump lubricates the bottom end via the hollow crank, the top end via the external oil manifold on the right side of the cylinder).

So I doubt that whatever damaged the pump then went on to damage your cylinder. More likely is you had some tranny damage, and these parts migrated into your cylinder and also snuck past the pickup screen to damage the pump.

Fourth gear, both of them, but especially the drive gear (one on the main shaft as opposed to the one on the countershaft) is the one that gave me problems on both my '00 and '01. I would inspect all the gears and replace both fourth gears unless they look absolutely perfect.

Replacing the forks is a good idea, this in fact may be what lead to your gear damage, but the shift cam I would keep unless you see any damage to the grooves etc.

Hope this helps.

Before you reassemble, make sure the gears slide smoothly and effortlessly on the shaft splines (the ones that are splined, anyway). One small, nearly invisible nick on a spline is enough to lead to a partial dog engagement and more gear damage.

On my '00 I had a chunk of fourth gear get lodged against the crank counterweight. Not good.

I also had some scratches on the scavenging pump star (rotor, whatever you want to call it) and its outer gear (or, again, whatever), but not enough to warrant replacement.

I found chunks (maybe gear pieces!?!?!?!) inside my flywheel and wedged behind my clutch basket. I haven't pulled the gears yet, but I have a feeling this is where it came from. I find it really strange that I am getting peices of a pin coming from the oil pump.

The previous owner dropped a valve into the piston and trashed a bunch of gears, but had it professionaly fixed and put 2+ years on it without problems. I wonder if there was some missed contamination that finally broke loose and got sucked up into the oil pump. Visual inspection of my gears looked promising, nothing obvious was broken/missing but I haven't pulled them yet.


thanks man! You're a big help and I appreciate it.

Hmm, since you found stuff on the clutch side of the motor I would, given that this is a 2000 model, make sure to inspect the primary drive gear, the balance drive gear, the straight key that holds the latter, the main nut, tab washer, and right case where it fits over the crank end.

It doesn't really surprise me that your scavenging pump is damaged given all the metal that ended up stuck to your mag, as I mentioned, I had some fairly obvious (but not terminal) damage to this pump after the tranny fragged on my '00, and the pickup screen was perfect. It wouldn't take a very large piece to make the pump star break the pin that holds it to the shaft.

It probably goes w/out saying that you should flush your oil tank and all the oil delivery lines. :)

And get a Zip-Ty magnetic drain plug. This probably saved me a lot of headache when fourth gear on my '01 chunked off a few bits.

Good luck.


Hick is right on with his breakdown of the oil flow. The thicker gerotor is only $13.00 from Yamaha, it can't hurt to replace it. If the high pressure pump (the one inside the steel cover and casting) is scrored in any way shape or form REPLACE the pump. The High pressire pump comes as an assembly (just as you removed it from the case, that runs just over $100.

I had to do both my high pressure pump, scavenge pump, 4th pinion, and 5th wheel gear. You'll see the culprit when you get the shafts out and on the bench. Don't be shy about looking at the forks closely, the bend easier than people think. The shift drum on the other hand is pretty tough, they don't wear all that much.

If you do a search on "YZF oiling system" you get a real good breakdown on the oil flow thru your engine, it's nice to review it while the motor is on the bench. You'll have a whole new appreciation for your ride!

You'll have a whole new appreciation for your ride!

Oh, I'm sure he does already. :)

Ditto what you said about the pressure pump though.

Yea Hick, you're right, but ya know...Once you get over the fact that you got to spend $$$. You make the teardown an adventure :)

I know I'm one of those sick minded guys that loves to see how things works. :)


What made you tear it down? What were the symptoms?


You were doing a rebuild on this one, right? Maybe some parts from a failed bearing.

Your concern with the oil pump is this: As Hick said, there's two. The outer, smaller one that lives in its own little housing is the feed oil pump. It gets its oil from the tank and sends it to the filter and then off to lube the important stuff. The larger inner one is the return, or scavenging pump. You already know you need the inner and out rotors, but you should be critical also of the plate that separates the two rotor sets, and the bore that the return pump sits in. The bore is machined directly into the crankcase, and only a little damage should be tolerated. Have a shop check it if you're in doubt. If you decide it's a problem, it may be repairable, but check the price against new.

If you had debris in the return pump, it's also in the oil tank. Remove the screen and clean the frame out, especially the return fitting at the steering head, and the return line, too.

My guess is that what damaged your cylinder originated in your engine, and then went on to your oil pump from there, screen or no screen.

I took apart the oil pump to find this


which I think was caused by this IMG_6402.jpg

but I have no idea what it is or where it came fom. I found it inside the oil pump assembly.

The oil pump is majorly FUBAR'd IMG_6404.jpg

What happened....

Out in the high desert crusing around very gingerly when the motor dies and locks up. I check the chain and all is well so I get a tow back to camp. Open it up to find the cylinder wall scored pretty badly (bored .040" to get the damage out) cause of something between the piston rings and cylinder (now I know it was the inner pump star mechanism peices).

I'm going to replace the oil pump assembly, the outer rotor gyro thingie, all shift forks, 2nd gear and possibly 4th gear too. I've already got a good deal of money invested in the big cylinder and getting my head worked so I dont want any surprises down the road. BTW... the drive gear and CB key were fine.


I do have some scarring on the inner bore of the return pump, but not enough to warrant replacing the case. I'll try to get a pic next time I'm up where my bike is. Its got a few lines grooved into it, very similiar to the star shaped part in the first pic.

Thanks for the input!

That pump rotor looks okay to me, but it is hard to say from a picture (even though that is a great pic).

No idear what that unidentified piece is. Is it metal (looks like it)? Is it part of a spring, or more rigid?

If it isn't a badly mangled spring or circlip I'm totally stumped as to its origin.

Its more rigid than spring material, its also welded at one end. I dont know if it was welded before or after it was introduced to my oil pump though.

I damaged the frame oil screen the day before my last ride so I removed it. I wonder if that peice was lying in wait and when the frame screen was gone it finally got ingested. I'm stumped.... time to resume the search.

I'll go out on a limb and say that the two pins you found are the ones that drive the pump inner rotors, so they did come from the pump. What ever the other mystery thingy is, I have no idea either, but it's time to get a search warrant.

Be sure you lap out any burring that stands proud of the surfaces in the return pump bore. If the old outer rotor is intact, use that to do it with after you lap it flat on a piece of glass.

I damaged the frame oil screen the day before my last ride so I removed it. I wonder if that peice was lying in wait and when the frame screen was gone it finally got ingested.

Not likely.

The oil tank gravity feeds directly to the (impeller-type) pressure pump. From there it passes directly through the oil filter. Then it travels to the bottom end via the crank, and top end and tranny feed tube via the manifold.

So unless that thing passed through the filter it did not get into the scavenging pump from the tank.

I have no idea what that thing came off of.

Wild guess: mangled piece of a roller bearing cage???

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