Dolmar 133 surging at high throttle

Kidneycutter · May 4, 2022

Here’s a vid of the problem
I have used foggysails fix on this ignition. Pressure and vac tested not sure what’s going on.

av8or3 · May 4, 2022

I think it’s running out of gas. Also , I have seen a saw behave similarly that had the valve membrane in improperly. It was my 133 super actually. Hard as heck to start and just had no guts. Turned out the membrane which should be installed against the carb body was in stalled over the sealing gasket instead. Im surprised I ever got it started. Best of luck, it’ll be the last thing you look at! Lol

Old2stroke · May 5, 2022

Have you tried backing the L screw out a bit? The low speed circuit may just not be rich enough to allow the engine to transfer from idle to high speed delivery.
A word of caution: Do not run a saw very long with the top cover off, without it, cooling air from the FW isn't concentrated around the cylinder and can seriously overheat.

pioneerguy600 · May 5, 2022

on the 133 that`s an ignition problem, it was on my own 133 and I had to change the entire ignition to solve it.. I think the ignition is trying incorrectly to act as a rev limiter or at least it seemed to on my 133.

Kidneycutter · May 5, 2022

av8or3 said:
I think it’s running out of gas. Also , I have seen a saw behave similarly that had the valve membrane in improperly. It was my 133 super actually. Hard as heck to start and just had no guts. Turned out the membrane which should be installed against the carb body was in stalled over the sealing gasket instead. Im surprised I ever got it started. Best of luck, it’ll be the last thing you look at! Lol

I sssume membrane is the diaphragm which on my parts list does sit on the gasket?

pioneerguy600 said:
on the 133 that`s an ignition problem, it was on my own 133 and I had to change the entire ignition to solve it.. I think the ignition is trying incorrectly to act as a rev limiter or at least it seemed to on my 133.