Tech Question Ski Doo 440F O-ring head gasket

[Djwirth]

hello everyone,

Having issues and in need of advice.
Recently bought 2 1999 Touring LE 2 ups 440 fan cooled. Both with 550 miles and "dealer Serviced" from an older couple that were the original owners.
I got one for my wife and one for myself to ride with my kids.

My first ride out, 28 miles, 25-38 Degrees out, trails in good shape.
Wifes sled ran great, she loved it.
My sled ran great for 26.5 miles and started to bog, poped threw the Intake and then quit. I was able to get it back home and found..
Right cylinder lost compression and the left cylinder had 125 psi. I removed the right cylinder head and found the rubber O-ring blown out. I replaced the o-ring, cleaned the carbon, new plugs, Drained the tank gas, and cleaned the float bowls and jets. both of which were nice and clean. I didnt mess with the Carb adjustment screws. I checked the left cylinder O-ring and it was Dry and cracked. I replaced it. Sled started and had 125 psi on both cylinders, thought i was good to go.

Second ride.. 30-40 degrees out, trails in good shape. 24 miles.
Wifes sled ran Perfect!
About mile 15 going up a Large steep hill, my sled lost power and i shut it down. I noticed oily residue coming out of the fan ductwork (thinking i blew another right side O-ring). I removed the Right side cylinder head on the trail and it was Perfect. i then removed the left one and found it Blown out. I was able to repair it on the trail and get back home.

Now.. what am i missing? I torqued the heads to spec. Fan belt is turning the fan and airflow is not blocked. Is it an over-heating issue? Am i too lean? On both cylinders? causing it to over heat? Could the Oil Injection system be miss adjusted? Wil that cause over heating? Do i need fatter jets (should be stock). Timing? (is there timing) My Wifes sled Ran fine all day and hers is 4 digits older on the vin Number.

any help would greatly be appretiated
thanks in advance
Derrick

[Djwirth]

Fanbelt had 3/4 to 1 inch of deflection. loose as a goose but it would still turn the fan. after replaceing the Fan belt and getting 1/4 inch deflection My 3rd run.
Same thing happened, except it was the right side again. so it went Right side, Left side, Right side. The left side is know to blow out when over heating happens because its farthest from the fan.
Im at a loss. Anyone know how to check ignition timing?
Any help would be great. and i mean ANY!

[classic]

what do plugs look like ? the porclin part ,are they like brown ,black or something in the color of white!! (hope not) if they are way too lean for a 2 stroke also check compression reason i ask is if there is not enough, gas is not burnng correctly causing either a lean or rich depending on how low it is if gas is going in cylinder and not burning off a piston wash condition exist and will wash off lubrication from piston and cause lean in that cylinder which in turn will heatup and gasket will let go from heat and high pressure