I have a 630 bobcat with a vh4d1 wisconsin engine that will not start,it trys to and some times will but will not stay running it will only start for a few secs and then not try again. When it first had trouble with it it had no power and found that both head gaskets were blown,I replaced them both and now have good compression and it is in time. Tried spraying starter fluid in the carb but still will not start. replaced plugs before this happened so they are new and they all fire. new wires, but have not replaced the rotor and distribitor cap yet but going to.. most of the time if you have gas and spark and compression it should run but this has me stumped, does any one have any suggestions for what to check, this bobcat had low power when i bought it, and i have not had it very long...