Chainsaw Repair

FWIW the S-25 has the gas tank right next to the cylinder and can cause the heat from same to boil the gas in the tank .I ran into that in Colorado in 1974 while deer hunting on an S-25 cutting camp wood .
Because the way the fan blast works often it will blow sawdust under the cylinder and block the flow.The cure is periodically remove the starter cover,clutch side cover and blow it out with compressed air .