Stilh 056 problems

[ltrr1971]

My older 056 super has not been running too good lately. It seemed that it did not have full power all the time and would stall out at idle and or need to run with partial choke to keep it running. After stalling sometimes it would not restart. At times if I held the throttle wide open the engine would rev up and slow down on its own as if I were blipping the throttle even though it was at full throttle. So, I took the carb off and took it completely apart and blew out everything and reassembled and installed. It ran good the first time for about five minutes. Later I restarted it and it is again revving up and down on its own at full throttle. If I push the bar into wood as it is revving up and down it runs even till I pull the bar out of the wood then starts revving up and down again. I'm at a loss. Anyone have any ideas?

 

[Metals406]

Dirty fuel filter? Bad carb? Blocked vent?

 

[Lakeside53]

It can be many things.. including bad seals/bearings. After looking at the easy stuff -impulse line, fuel filter, carb boot, carb inlet screen, tank vent (cap) etc, you need to perform a pressure and vac test.