first thing to do is see if youre getting any spark. to do this, put the sparkplugs in their boots and lay them on the head and ground them (make sure the hex or threads are touching a nut on the head on all three cylinders). next, hit start and make sure all 3 plugs are sparking nice and bright blue and in a consistant fashion.

after your spark checks out ok, youll want to do a compression test. to do this, youll need a compression guage. you can buy one at any auto supply. theyre usually not so great unless you buy one of the higher-end tools such as everybodys favorite, Snap-On! anyway, enough endorsements...... youll keep everything just like it is for the spark test, but this time youre going to screw the guage into the sparkplug holes, one at a time, and hit the starter until the guage stops climbing (usually about 5 seconds). once the guage stops climbing, write down the PSI reading on the meter then go onto the next cylinder. i believe you should be getting a reading of about 135 psi in each cylinder. i could be wrong on that number, but thats not the point here. the point is that you want consistant numbers between all three cylinders with no more than 5% difference between any 2 cylinders. but the numbers should be roughly equal and between 115 and 140 lbs psi (once again... i dont have the manual in front of me for exact numbers).

also, did you change your gas? if not, how old is the gas? you said you premixed the oil into the fuel. at what ratio did you do this and what kind of oil did you use? do these skis have oil injection still or is the pump and tank removed for premix?