If you don't want to take it apart, don't have the time and tools, I would pickle it...
fill it will diesel fuel and maybe a bit of 2 stroke oil...
Fill the crank case and also little down the plug holes, and after a day of sitting (don't turn over with plugs in) with the plugs out gently tap down on the highest piston with a dowel...
Once she frees up pour another ounce of oil 2 or 4 stroke in each cylinder and rotate it several times, then put a line on the crank case breather into a bucket and purge the engine of the pickling juice by rotating it... A drill could be used on the clutch, if you rotate it a ton you may want to use a bit more oil in the plug holes... once it no longer has any diesel left, re introduce some 2 stroke mix gas in the case and purge then repeat 2 or 3 times to get all the diesel out...
Then start...
I have done this to motors that ran for many hours after, I also have done this to motors that didn't run ten minutes... It's all in what damage has been done...
It is by far a better idea to dissasemble the motor and inspect everything...
Remember you can go further on snow using a snowmobile in 30 minutes then you can walk in a day!