Supertune Chuck walked me through some stupid questions I had on oil pumps on the old forum. I still have some questions about the oil pump on my 85 RZ350. I rebuilt the pump and it works fine as far as I know, but checking the stroke with a dial indicator at idle I get .008-.009" of stroke. The RZ manual calls for 'minimum stroke of .004-.006'. So my questions are: Is .009" way too much? More stroke=more oil injected? How do the shims affect stroke, i.e. does more shim thickness=more stroke, or other?
I know Chuck posted a method whereby you remove the cover/pump and drive the pump with a drill to get an absolute verification of oil flow, but in my laziness I was trying to avoid taking it back apart to do that. Thanks!
Assuming an RZ is the same as A/C RDs. The shins add to the MINIMUM stroke and that's all. A feeler gauge is much easier and more accurate way to measure minimum stroke on RDs...
I do believe the minimum stroke at idle is not the only thing the shim affects. It will impact the stroke at all speeds. The shim sets the pump depth by raising or lowering the large washer that bounces off the pump stop. It wont allow the pump to travel out any farther, but it will allow the pump to travel down a bit more.
The higher the washer, the more oil that the pump squirts in and the more oil it does so at all speeds. At least until the pump bottoms out at which point you've hit the limit the pump can send.
Too much minimum pump stroke will usually just foul plugs, especially at low speeds and city driving. A minor nuisance, but no harm other than excessive carbon build up if run that way for a long time. Easily corrected using brass shim stock if you don't have any of the Yamaha pump washers.
HTH,
Jay
.009 is fine, a tick rich on modern synthetic oils, all depends on the engine build.
Chuck
Thanks for your help guys. May try to lighten it up a bit. It is a mostly stock RZ with a fresh rebuild, Toomey pipes with the big K&N filter. 1st oversize pistons.