I have about 20 tanks through it and I think it could use a tune. It's bogging down on me a lot. From what I understand, I should drill holes into the muffler? (where?) (what size?) and then go through the typical carb tuning process. I haven't tuned a Stihl carb but I think I understand the basics. How do I go about doing this in a methodical, non-dumb way? Bonus here is a 10" diameter ash I took down this morning. The saw bogged down on it quite a bit and got me thinking it's probably broken in enough to think about a tune up: https://files.catbox.moe/gvvyqj.mp4
Is it possible you have your drags filed down too much? It wasn’t bogging when new? Air is denser when cold, so maybe H needs 1/8 turn clockwise. Does 251 have carb screws?
I bought a 251 when they first changed from the 025's The mom and pop dealer (years and years of reputable dealorship) told me that after 4 or 5 tanks of fuel I should adjust the carb as per the manual. I did and it has been flawless ever since. I did richen it up a little so it is "4 stroking" when it is working hard. No muffler mods or nuthin. Hows the air filter look? It dont take much to clog them up.
Below is a link from Madsens on how to tune a chainsaw. Plenty of resources on YouTube. https://www.madsens1.com/carburetor-adjustment-on-pro-saws You don’t have to modify the muffler but it can help get more power and heat out of the power head. The saw will also be louder. The carb will have to be adjusted. I went the cheap and dirty route with my MS251. I made two fish gills with a dremel and opened them up with a screwdriver. There’s deflectors you can buy also.
Yeah the chain just stops. This is on dense hardwoods primarily. I'm confident in my sharpening (using a 2in1 actually). I just think the engine needs breathed on a little.
Maybe leaning out the high side fuel screw 1/8 turn at a time and test cut in-between each adjustment. If it doesn't improve within 3 adjustments id set it back where i started and look at raker depth on chain.
I also use 2-1 sharpeners but I found they make the chain to aggressive by making the rakers to low. I removed my raker file and do them separately using west coast progressive raker plates. The aggressive chain wasn't much of an issue on my ported saws but on a stocker they were practically unusable in hard wood.
