I took the oil pump out today and to me it needs replacing..... But I found another selling on ebay in far worse condition: https://www.ebay.com.au/itm/Oil-Pump...oAAOSw6-tbuvDk

Hopefully someone can point me in the right direction as to what condition is considered replacement...

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I recently replaced my 3AJ pump because it was shot:

https://www.horizonsunlimited.com/hu...-damaged-98084

I replaced it with a 2nd hand one from a XTZ660. It's the same pump, also has 3AJ on it. I think even the newer 2007 model XT660Z's pump is pretty much the same, although don't pin me down on it.

Anyway that pump on the picture I wouldn't use. Is that the replacement or your own one?
Here's some pictures of my 2nd hand one:

https://imgur.com/a/zJfbt23

Hi saintnz,

I have a 2kf for some years, learned how to make the engine last after a rebuild. Below is one of the articles i wrote, there are more but this one addresses the cause and effect of engine failure; 5th gear fails, metal particles destroy oil pump, oil starvation to piston and camshaft.

https://www.horizonsunlimited.com/hu...solution-80123

You say "engine locking up after 5 mins of running". The pump can look terrible and still pump enough oil to prevent seizure.

Modifications made by Yamaha to XT600 over the years can cause confusion. 2kf didn't come out with a 3AJ pump. If you fit a 3AJ pump you also need to fit a 3AJ drive gear. Again, the gear can be fitted wrong way around, the pump works intermittently and can run for months before piston locks up. So check those.

Then, take some advice and protect the oil pump with strong magnets near the oil strainer.

Best,
p

agree with pete.... this is a mostly ball bearing engine, just the cam is plain bearing, very unlikely that it seizes due to not enough oil.... unless the pump is simply not turning for some reason.


Agree also on the fact that a badly scored pump is an almost sure sign of (the usual... ) 5th or 3rd gear damage, so not good news.


not much fun to do but to me it sounds like you need a full disassembly and finding out where is it seizing and to check the tranny.

HI Peter, what do you mean by this? If I remember correctly, the gear looked identical/symmetrical to me. I put it in the same way it came out, but looked like it didn't matter.

DYP, if you put it upside down pump will suck the oil off the engine

Hi Doubleyoupee, Turboguzzie, cc saintnz,

You're testing my memory.
The pumps: there are 3 pumps to be found in XT600s, in each the oil pump capacity was increased to address issues experienced with enlarging the brilliant XT550 (5Y1)engine to 600cc. The pump rotor was widened from 4mm to 6mm (1VJ) and finally to 8mm (3AJ). All pumps have 18mm scavenge rotors.

The 4mm pump has no marking in front, only 5Y1 on the back, as have all the others.
The other 2 are marked in front 1VJ and 3AJ respectively.

The gears: The 1st and 2nd pumps are physically the same size, so use the same drive gear, a dished gear without any marking, fitted with the dish facing away from engine, if i remember. The shafts on these 2 pumps had a single groove, for the circlip holding the gear in place.

The 3AJ pump, listed under various part numbers, was enlarged to accommodate the final wider pump rotor, and therefore needed the gear to be less dished to meet with it's mate behind the clutch.

Therefore you MUST fit a 3AJ gear with a 3AJ pump.

The shaft of this pump was marked under where the gear sits, with 2 shallow grooves, just as an identifier.

To explain the 3AJ gear being installed in back to front; the gear will fit both ways. It is nearly flat, but installed incorrectly will drive the pump intermittently and result in unreliable oil pressure.

I know, because, in a senior moment, i put that gear in wrong way around when repairing the little screw come loose on gear-change drum pawl. Bike ran like that for about 6 months without a sign. On a day, moving off from a traffic light, it gave 3 distinct consecutive pinks. While wondering 'where that came from' riding with thoughtful care, i felt the engine started to tighten up.

We ride on the left here, and after a quick oil level check, leaning over to the left, i turned the engine over a few times with the kick.

Started the engine to a new slight rattle, and rode home. And rode another +/- 100 while trying to diagnose the tappety noise. Gradually realized what i was going to find.

Happily that was a few years and many thousand km ago. I corrected my mistake, it still has the clatter, but maintains its knee-crunching compression if i get things wrong, and runs up to 160kmh way easier than before.

best,
p

Thank you very much for the help.

The pump I removed has 1VJ on the outer casing.... The gear wheel has 3AJ and that was facing up looking at it directly... if that makes sense... so the flat side was facing in towards the pump (inside)

Hi there, thats exactly what happens with mine.... you can feel it starting to tighten up..... is it possible the combination of the 1VJ and 3AJ wheel is the problem? It was running reasonably ok when I got it, but I always felt it was restricted somehow...

So the oil pump gear is inline with the other gear but not central... hopefully you can see from the photo

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The pump shown is the one I pulled.... I brought a secondhand one off ebay that "looked" ok and confirmed by the seller it's in usable condition but it's for a early XT...... If all is well and it runs fine I will look at a new 3AJ pump..

Thanks for your help