Oil pump swap
 

I have a low mileage 1986 XT600 43F. I have had to replace the shift cam assembly. So I have the bottom end apart. It seems like it would be a good idea to replace the oil pump upon reassembly. What is involved with replacing the oil pump with a newer model one as suggested? It is just a replacement of the plastic gear or is there more to it? Thanks for the help in advance.

Swapping is easy
 

Yes, just get a new pump, the plastic gear and the circlip holding the gear to the pump shaft. C'est tout. And new O-rings, of course.

BTW, there three types of pump:
Marked 5Y1 - 100% capacity
1VJ - 150%
3AJ - 200% - that's the one you want.

Auke