i agree with blasterboy. premixing may be a little annoying, but it's a lot better than havin your oil pump randomly stop working, not knowing it, and smoking your top end and possibly crank and rod bearings.
there is a way to check it, get a clymer manual and it tells you. drain your tank and carb bowl and premix 24:1. (i know, really rich, but thats what the book says). take the cover off the oil pump, take the hose off the carb (it has a metal band, slide it down the hose before you pull it off, makes life a lot easie! then when you hook it back up, slide the hose on the nipple, then slide the band back up). put then end of that hose into a small graduated beaker or graduated cylinder. plug the nozzle on the carb to keep air out. remove the cover from the front of the oil pump to expose the piston shaft. ok it then says... have an assistant start the engine and allow it to idle, count the number of piston strokes up to 200, then quickly turn the engine off and measure the amount of oil in the beaker. should be 3.47 - 4.23 cc (0.117-0.143 U.S. oz.) then reinstall the cover on the pump, drain the premix, refill with unmixed gas, and bleed the oil pump.
to remove the pump: drain the tranny oil. remove right side footpeg. remove oil pump cover, disconnect supply hose and delivery hose and plug both. remove right crankcase cover with pump. remove e-clip on drive shaft. slide oil pump gear off drive shaft. remove pin from hole in drive shaft. remove second e-clip. remove 2 screws that hold oil pump to right crank case cover and remove pump assembly. remove and discard gasket, remove washer from drive shaft. remove drive shaft from right crankcase cover. do not allow the oil pump to contact dirt (store in plastic bag)
to inspect the pump (must be removed first): make sure all gasket material is removed from both mating surfaces. all parts except oil pump housing can be cleaned in solvent. inspect oil pump for leaking seal or any visual damage. replace if any damage is noted. do not dissassemble oil pump unit. inspect washer for nicks, burrs, or damage. inspect drive shaft for excessive wear, nicks burrs, or other damage. (now the part that always fails!) inspect (PLASTIC!) oil pump gear for excessive wear, cracks, or damage. inspect drive shaft bushing for wear, damage, or loose fit in right crank case cover. inspect drive shaft seal for tears or signs of leakage. lubricate all the junk with transmission oil (except seal, use grease) when you put it back together.
that was a lot of typing, and probably pointless, but hopefully it helps someone lol. i say just remove the little (plastic!) gear, block the nipple on the carb, remove the oil tank, and premix.
