How can I fix my McCullock TM 250 petrol engine?

1: Is your idle screw set high enough.
2: I had a problem with the cylinder barrel coming away from the crankcase which affected carburation.
The carb relies on crankcase pressure to function correctly. To check this, hold the back of the strimmer and see if you can move the air filter forwards and backwards. You should have no movement.

Binnon
August 2007