I have a 260 pro it starts fine and kinda cold natured until warmed up. After warmed up it's hard to start and wants to die when you let of trigger to idle. Any ideas what the problem is?

have you replaced the vacuum line ?

have you vacuum gauged it to make sure no air leak?

my MS260 had the vaccum tube crack and suck air , they run great , too great when reved up because they are running lean.

also pull your muffler and look to see if the piston is scored that is what happened to mine , I rebuilt it and ran it 2 more years and it did it again.

I have a complete one in my parts bin if you end up needing anything.

Not to hijack a post GCP I'm just curious if the vacuum leak was fixed when you rebuilt the saw, reving up a cold saw can sure cause a scored piston.
Sage .

the vacuum leak was the little hose to the carb I replaced it but too late the piston was already scored. everything was vacuum tested and held when I put it back together but at that point it was a decade old saw and something else let go after another 2 years I wasn't easy on it in those 2 years either , bucking 30 inch rounds till the gas ran out then fuel up and do it again and again

after the rebuild it ran great would sit and idle for a half hour if you let it.

I sold it for parts and bought a bigger saw to do what I really need to do , rip through 30 inch rounds over and over

Low compression will do that. Could be burned up, could be a stuck piston ring.

Take the jug off and inspect the rings and the inside of the jug ....... I am with Pat on this one. low compression when warmed up

Two problems the carb and the fuel line in the above the handel. The carbs are assembled with a resin or a glue substance it's failing and the short hose for fuel is got a pin hole one of them two I replaced bothe lastyear and bach to running like a bear

Add a touch more fuel on the low speed jet.

Pin the throttle trigger on restarts after its warm- I have (2) Ms250's same issue

I would take the muffler off and look the piston over, if it looks good do a compression check, if good change the impulse line, next would be diaphragm in carb

Maybe adjust the idle up a bit.

A quick compression check is to hold the saw up by the pull cord. If it drops at all there's compression issues. We did this all the time at the dealership I worked at. Even a big saw will hold itself up pretty good. If it drops to the floor you got problems.

X2. It could even be a piece of dirt in the low idle jet. Turn it back and forth a couple times.

Crank seals are easy to replace.

Thanks for that tip! Never heard of that, good way to check out a used saw before buying.

I would try what Ohio said. Open the low speed a bit. You can check if it's got an air leak by starting it up and spray some wd 40 around the seals, crank carb ect if it's an air leak around the seals when you spray it it will kill the engine

Mine had a similar problem had the fuel line changed and fixed the problem.

had one that done the same thing. replaced all lines but still did it. Ended up being scored cylinder jug.