Originally Posted by gvthnks
don't disable the oil injection system. It'll start and run fine for a few minutes and then the mains will die. as someone above stated, that generation suzuki used the premix injected onto the mains to lube them.
I would clean and inspect each of the hoses that run to and from that oil pump. if any are dry rotted or pinched or cracked they'll leak or cause issues. There may be a oil filter inline somewhere too and that needs to be clean so it doesn't restrict oil flow. By all means get all the old oil out of the oil tank and flush it to ensure it's clean. Any dirt or grime in there will be injected into the motor. I've never seen an oil pump fail if it was run in clean oil. They fail when dirt is allowed into the system or they're run dry. There's also an adjustment that allows the oil pump to be calibrated to the throttle opening. don't remember how it works on a suzi, but your service manual will probably detail it.
If it was me, and it's not, I would most certainly change the crank seals. They're cheap, and after 30 years theyre either not sealing well or they won't seal well under the new pressures that the new piston and rings and cylinder will create. If the magneto side goes it'll suck air, run lean, and you can burn a piston in a hurry. If it's on the wet side, it'll suck oil and foul plugs. Seals will cost you 25-40 bucks for both and will ensure its done right.
Good advice here, you will destroy the LH main if you try running premix without the oil pump.
Yes looks like it was lean, could be air leak, or more likely partially plugged jets.
You can bleed the oil pump by loosening the phillips head "banjo" screw on the face of the pump, (this bleeds the tank to the pump), then once it is running just hold the lever on the pump to full open and you should see the oil pulse through the line. To calibrate it there should be a plug in the side of the carb slide body, you remove it and turn the throttle until you see a dimple in the slide through the port, at that point there should be a line stamped in the oil pump arm that lines up with one cast in the pump body.
And what he said about the seals,if they leak. I would only do the mag side though, the clutch side requires splitting the cases and pulling the main bearing. If it sucks oil after you get it running then you will have to split and replace.
Some of the later Suzuki 2 strokes had the nikasil (SP?) coating on an aluminum cylinder, if it does just hone it, if it is a iron sleeve, then it can be bored. The one pic looks like it is sleeved.