Hi all,

I'm in the middle of a full engine rebuild. When I removed the oil pump, there was some huge chunk of rubber sitting around the shaft inside the cases. As far as I am aware that is not meant to be there right? The oil seal was also missing from the bottom of the oil pump that seals the shaft. I think the previous owner must have used this piece of rubber to try and stop 2 stroke oil making it's way into the cases in lieu of the correct seal? There was also a washer which looked like it had been used as a shim at the bottom of the oil pump shaft (similar to how there is a washer used as a shim on the water pump shaft).

So my questions are these:

Is there meant to be a shim there? I can't see anything on the parts diagram or in the workshop manual that would suggest there is meant to be? I'd be worried about it making it's way into the cases.

Does anyone know of the part number for a replacement seal that seals the shaft where it comes out of the oil pump?

Much obliged,
Jim

By the way. I went ahead and had the cases wet blasted while I had them apart. I know it's a bit over the top considering most of the engine is hidden behind the fairingsa but the result was still very much to my liking. Photo attached.

If you look at page E14 in the Online Parts Manual, you will see there should be an M8 thrust washer between the pump shaft and the crankcase. This is to prevent the shaft from chewing into the soft alloy. (A cheap production alternative to a hardened steel insert/bearing.)

There is no official seal part number, but there are alternatives that have been used successfully. There have been a number of threads about it already, and you should be able to find some good info with a search.

In fact, try this: http://nsr250.net/forums/viewtopic.php?t=11190&highlight=oil+pump
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Andy.
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nice cases

Do a search for oil seal and you'll seal an equivalent part used for go-karts (if my memory serves me correctly). Be sitting down when you do your price researching though.

Thanks guys. Really appreciate the assistance. As per usual I should have done more hunting around before I asked the questions.

Cheers
Jim