97 zrt600 possible oil pump trouble

[sir_switch]

After completing a total engine rebuild on my 97 ZRT600, I find alot of excess oil at the bottom of the belly pan. The oil appears to be flowing through the brass nipple on each of the carb boots even after the machine is shut off. I also have an excessive amount of 2-stroke smoke during start up and a bit of backfirring. At this point, the machine will only start once I pull all three plugs and dry out the cylinders, I suspect that I have an oil pump issue but I''m not sure on the proper adjustment or how to confirm that this is my issue. Any thoughts or trouble shooting tips would be appreciated.

 

[JimAndros]

The fittings on the pump (outlet side) that the oil lines run from to the carb boots are check valves. It takes approx 4.5 to 5 psi to open them & they close again at 3.5 to 4 psi. If they are allowing oil to pass due to gravity, they are faulty. Also, be sure the tank is vented properly. If it was filled cold and then allowed to warm with a plugged vent, perhaps it couild be building enough pressure to pass the check valves.

 

[mjkaliszak]

I'm going out on a limb here but my belief is that OP's fail full open. This is rare that they fail but I did have one go bad on my POO two years ago. The cross-shaft bearing was leaking into the case. If you want a suggestion on how to check ? ? ? I will stick my neck out again and offer up a suggestion. My pump to carb lines ooze oil after shut-off, the so called oil pump is actually more of a meter than a pump ( JIMO ).

You could get a drive adapter for your hand drill, pull plugs, pull belt, and pull oil lines off carbs & case ect...
Turn motor over with drill & socket at primary and check flow, then pull the throttle WFO and turn over with drill. At that point you should see more flow @ wfo than when not squeezed.
Someone may have a better idea but that is mine. You should have alignment marks on your pump arm.
Those mikuni pumps are expensive, mine cost about 150 a couple years ago.

 

[sir_switch]

Thanks gentlemen for the advice....I'll give it a try. With no snow on the ground yet I have plenty of time. One thought that I had was to simple disable the oil pump (remove the lines to the carb and cable to the throtle) and run the machine on a bit of mixed gas just to confirm that my OP is the issue. Once I fix things I'll post the results...Thanks again.