I do know you have cleaned the carbs. Assumeing everything was done correctly to them that leaves electrical. That is unless you still have tors caps, could be problem with those, water/ice. You will have to check everything from the stator to spark plugs. Check stator for moisture/ rust. Pick-up gap. Check every connection for corrosion, add di-electric grease on re-assembly. Plug cap to wire connection, maybe cut 1/4 inch before re-assembly. Check coil ground. Test/inspect all switches for moiture/corrosion. IF you happened to go through any salty water on your snow ride, it will make the poblem even worse. Do you have tors or parking brake "brain boxes" hooked up? Hope this helps.