Servicing the oil pump

I bought a used oil pump for my 750. The plan is to disassemble the pump, lap the body as described in the manual, and then fit it to the bike to hopefully improve its wetsumping problem (drains the oil tank in about four days).

Disassembly was no problem and all the parts look good, so I just need to lap the body (and clean it thoroughly) and it should be good to go.

But - there is that flanged bushing that the cone washer sits upon. The flange projects out beyond the pump body, which prevents lapping that side of the body. The manual is emphatic about lapping the body, not the cover plate. It appears the bushing needs to come out, but I don't see any obvious way of removing it. I would imagine it's a pretty tight interference fit in the body.

What do you guys do about that? There's not much wear on this pump so I suppose I could just lap the brass cover plate. I would like to do the job the *right* way however.

Debby

debby said:

But - there is that flanged bushing that the cone washer sits upon. The flange projects out beyond the pump body, which prevents lapping that side of the body. The manual is emphatic about lapping the body, not the cover plate. It appears the bushing needs to come out, but I don't see any obvious way of removing it. I would imagine it's a pretty tight interference fit in the body.

What do you guys do about that?

Click to expand...

= Us guys would pull the bushing out of the pump body :wink: , as it shouldn't be a very tight fit ?

Look out for a shim between the flange and the body.

:lol:

Thanks, Les! I'll give that a try. I have a junk pump body I can practice on, in case I damage something...

Debby

failing that just file the flange off flush to the body

I got it! I was able to grip the flange with pliers and carefully work the bushing out of the pump body without damage. Yay!

Lapping is underway, although I have to take it a little at a time due to arthritis in my hand.

Another dumb question: what is a good grade of sandpaper to use? I had some 320 wet/dry so that's what I'm using. I need to go buy some more though. I just had a small piece and it's already used up. The book says to use emery cloth. That seems like it might be too coarse? It would make the job go faster though.

Debby

Start with a coarser grade (100) and finish it off with finer grade (400). Be carefull, coarser grade "grabs" more.

Jean

I wish you all the best in trying to cure the diabolical Norton wet-sumping problem. My experiences suggest that curing the wet-sump problem requires more than tightening up some of the clearances in the oil pump. Also, tightening the internal clearances in the pump makes the gears susceptible to binding. It’s a good idea to check for binding before installing the crankshaft pinion gear. You can easily do this by fully torquing the pump to the engine case, sans pinion gear, and then turning the pump drive gear by hand. Any rough spots while turning the drive gear are evidence of the gears binding.