426 Oiling System Improvements???

check out my latest idea:


Jerry in Deltona, FL

[ September 06, 2002, 02:43 PM: Message edited by: jerry426 ]

Jerry, I think your idea some merit.

My only question is where did you get the .0025 of an inch number and do you think that change will be enough to notice a difference?

Jerry, yeah that happens to these bikes. You have the oil path figured. I followed the link back to the teardown page. No, you won't need the crankshaft installation tool, or at least I didn't on a WR250F. The only thing that was odd about the crankshaft (other than connecting rod being welded to it) is old crankshaft timing chain sprocket was a tight fit in the inner race of the left main bearing. The new one fit easily. The journals slide onto the bearings easily, no pressing. The back plate of my oil pump, the one that separates the two rotors, was worn but I couldn't find it as a individual part. Any ideas on how to find one that isn't $89 or what kind of coating that is to have one made?

It seems to be common, these bikes look brand new inside. I'm always impressed.


Oh yeah, the heat marks on the crankshaft are from assembly heating. Some don't have it, some on one side, some on both. I expect it depends on how easily it pressed together or perhaps if they had to press it apart and reassemble.

Good luck,


I dunno, you are robbing Peter to pay Paul with your idea.

Originally posted by Hick:

I dunno, you are robbing Peter to pay Paul with your idea.

Oops. I just read your page more thoroughly and saw that you've figured that little caveat out already.

So, nevermind. :)

yznvegas: I measured the original hole size and found a drill bit that would be .025 larger.....so I figured .025 was as good a number as any. I didn't want to go too big and starve the top end, so I tried to guess a size that would achieve the desired result.

Mark: That oil pump plate seems to only be available with the entire oil pump assy. I'm thinking they could have done a nicer job with the oil pump.....such as bolting an entire steel oil pump in there instead of running the oil pump rotors DIRECTLY in the aluminum crankcase.....which would allow replacement of the ENTIRE oil pump with out having to buy engine cases.....but then they'd not make as much $$$ selling parts I suppose....



I hope your experiment works out.

Normally you would think a jap bike would have a trouble free oil system.

Remember the original Honda Magna? (The first muscle bike) it was plagued with oil starvation on the top end. It just slowly destroyed itself, period. It was recommended to avoid warm ups completely, just fire it up and go to get the oil pressure up. The mod that corrected the problem externally routed oil from the main oil gallery to the top end.


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