Re: Question About Exhaust
Oil coming out the exhaust.....have you checked the plugs? If you have that much blowby, I would suspect your topend is toast or possibly a hole in a piston. I assume it runs, but do a compression check. If everthing tests ok, then put some fresh plugs in and check your low speed jetting. If its pumping too much oil and not enough gas, this can do what you're describing, but fouling plugs like crazy.
You mentioned blocking off the oil injection. I did this right after I bought my Sharks and now I premix 40:1 with Pennzoil Premium Plus. For older skis, they recommend this since the injection can burn up an engine if it decides to go south on you.
Hope everything turns out ok.