Over the last couple days I have been playing with a 55 and wanted to try a 028 stihl pop up piston.
I first set up the cylinder and cut the base so it would be .040 thousands with a base gasket and stock piston.
Then I started fitting the 028 piston. I cut .030 of the main part of the piston and went 10mm wide. Then I took .060 off the dome top. It cleared 1 spark plug but not others , so I milled a spot for the ground strap to fit with a ball end mill.
Got the saw running for about a minute and then it died.
I could get it going with the choke and then high idle it would run. As soon as I take it off high idle it starts to act up. Tried leaning it out to 3/4 and no good. Turned it up a 1/4 at a time and it always seems like it would bog out with the throttle. Went all the way to 2 turns out. Still couldn't get it to run long enough to try some adjustments.
The port timing is
Intake 77
Exhaust 106
Transfers 127
BD 21
Squish is .024
New fuel filter, new impulse rubber, intake boot.
Not sure if it's the carb, fuel vent or something in the timing.
Saw ran fine before the experiment.
I never did a pressure and vac test . I guess that's next sometime this week.
Any ideas would be great.
I first set up the cylinder and cut the base so it would be .040 thousands with a base gasket and stock piston.
Then I started fitting the 028 piston. I cut .030 of the main part of the piston and went 10mm wide. Then I took .060 off the dome top. It cleared 1 spark plug but not others , so I milled a spot for the ground strap to fit with a ball end mill.
Got the saw running for about a minute and then it died.
I could get it going with the choke and then high idle it would run. As soon as I take it off high idle it starts to act up. Tried leaning it out to 3/4 and no good. Turned it up a 1/4 at a time and it always seems like it would bog out with the throttle. Went all the way to 2 turns out. Still couldn't get it to run long enough to try some adjustments.
The port timing is
Intake 77
Exhaust 106
Transfers 127
BD 21
Squish is .024
New fuel filter, new impulse rubber, intake boot.
Not sure if it's the carb, fuel vent or something in the timing.
Saw ran fine before the experiment.
I never did a pressure and vac test . I guess that's next sometime this week.
Any ideas would be great.