Kitty Cat Snowmobiles

This is my last resort. I have two boys wanting me to come through for them and I've failed thus far.

I have a '72 "B" Kawasaki engine that won't start or even sputter. I have a very strong spark, I have fuel, I have 75 lbs. of compression. I've cleaned the carb now four times, all new fuel mixed at 25:1 with Klotz, and unobstructed intake and exhaust. Not sure what else is needed for this thing to run like it did last year.

Any suggested would be appreciated.

I bought a new 18 mm carb and that fixed the issue. Starts great, idles great, but does not have enough power to pull any weight, even with very little snow. Does anyone know what the compression for this should be?