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Having MT issues with a 261 I just finished. This is the second one I’ve done that has had a problem.
The saw:
MS261CM manufactured 11/18
30 out of chamber
45 off base
Squish true .015
Timing advanced 1/4” of travel at Flywheel perimeter
Muff Modded
Extension trimmed and semicircle cutouts relieved.
Didn’t touch piston or stratos.
Ran factory reset on the MT 3 times.
Running pump gas with Motul800 at 32:1.
Issue:
I’m running a 25” 3/8 full comp, which is entirely too big for the saw. I wanted to see the difference full porting would make vs. just a TA/MM. Without nice square wood I figured a bar this big would make or break the question of what performed better.
Maybe this much load is just too much for the lil’ guy, but I don’t think a saw should heat up and do odd shít. Maybe I’m asking too much from it and it’s telling me GFY Al.
Runs fine till it’s loaded up good, then odd stuff occurs. Loses power in the cut, then sputters, then sounds lean. After a bit of time, saw comes back to normal.
Pulled carb after issue, popoff pressure >35psi. I couldn’t even get it to pop at max Mitivac pressure. Lowered popoff to around 35psi. Got same deal.
My thoughts:
1- Fail Safe? Saw gets too hot and MT says Uncle?
2-Vac leak? Haven’t checked yet, but will. MT can compensate until saw gets hot, then GFY.
3-More Power needs more fuel, and popoff too high. Running out of fuel in cut, gets hot, MT can no longer adjust. Does Weird Shít again.
4-32:1? Too viscous a mix to flow enough for the MT?
Saw seems to make no power suddenly. Happens like a light switch. Then a piss rev sounds way lean. Wait a few seconds, piss revs back to normal. Normal power again.
Fuel same as run in other saws without issue.
Sorry for long winded post. Wanted to be as descriptive as possible.
Thanks for the help.
The saw:
MS261CM manufactured 11/18
30 out of chamber
45 off base
Squish true .015
Timing advanced 1/4” of travel at Flywheel perimeter
Muff Modded
Extension trimmed and semicircle cutouts relieved.
Didn’t touch piston or stratos.
Ran factory reset on the MT 3 times.
Running pump gas with Motul800 at 32:1.
Issue:
I’m running a 25” 3/8 full comp, which is entirely too big for the saw. I wanted to see the difference full porting would make vs. just a TA/MM. Without nice square wood I figured a bar this big would make or break the question of what performed better.
Maybe this much load is just too much for the lil’ guy, but I don’t think a saw should heat up and do odd shít. Maybe I’m asking too much from it and it’s telling me GFY Al.
Runs fine till it’s loaded up good, then odd stuff occurs. Loses power in the cut, then sputters, then sounds lean. After a bit of time, saw comes back to normal.
Pulled carb after issue, popoff pressure >35psi. I couldn’t even get it to pop at max Mitivac pressure. Lowered popoff to around 35psi. Got same deal.
My thoughts:
1- Fail Safe? Saw gets too hot and MT says Uncle?
2-Vac leak? Haven’t checked yet, but will. MT can compensate until saw gets hot, then GFY.
3-More Power needs more fuel, and popoff too high. Running out of fuel in cut, gets hot, MT can no longer adjust. Does Weird Shít again.
4-32:1? Too viscous a mix to flow enough for the MT?
Saw seems to make no power suddenly. Happens like a light switch. Then a piss rev sounds way lean. Wait a few seconds, piss revs back to normal. Normal power again.
Fuel same as run in other saws without issue.
Sorry for long winded post. Wanted to be as descriptive as possible.
Thanks for the help.
Last edited:
