UPDATE to the issue with this MS-180:
Success! This saw runs flawlessly now, and there's no more spitting oil and fuel everywhere.
What I did: ordered a Walbro WT-215 carburetor, made the modifications to the air box and the housing to gain access to the H, L, and LA screws. I also added a paper gasket between the metal portion of the air box and the intake side of the carburetor - don't know if that did much, but there was so much oil/fuel in that area that I thought it couldn't hurt.
There are some videos on the web showing that you need to bend the throttle linkage in several different places, but I found that just bending the forward "hook" of the linkage forward about 1/8" worked perfectly to reach WOT.
Also, since that strange little black filler panel MIGHT have gotten in the way of WOT, I cut out the area just forward of the throttle linkage movement as it approaches WOT - did this with a Dremel. I didn't look for any clearance issues during fitment, but this was an easy modification, so it was done too.
Last modification was to free the exhaust flow a bit. I didn't go crazy, opting to open the vents up a bit with a large flat-blade screwdriver, and then I drilled those same vents with 3/16" drill bit one hole in each vent for a total of four holes and also removed the spark arrestor. Did the muffler mod make a difference? I don't know.
The final step was to tune the saw. Normally I do this with a digital tachometer, but I tuned this one by ear, backing WOT off a fraction of a turn until it 4-stroked a bit, then tested it "in the wood". I had to back the screw out maybe 1/16 of a turn to get the smooth WOT running in the wood and a slight bit of 4-stroking when pressure was taken off the chain.
SAW RUNS BETTER THAN IT DID WHEN NEW! I highly recommend the carburetor change to anyone having issues tuning (or other problems) with a 170, 180, MS-170, or MS-180.
PS: The "Stihl" (Zama) carburetor that came with the saw is marked "China" - discovered that when I could see all sides of the carburetor. Stihl is just not what it used to be, and I was VERY disappointed to see Chinese crap on a Stihl product. Glad most all of my Stihl equipment is 10-30 years old!
Success! This saw runs flawlessly now, and there's no more spitting oil and fuel everywhere.
What I did: ordered a Walbro WT-215 carburetor, made the modifications to the air box and the housing to gain access to the H, L, and LA screws. I also added a paper gasket between the metal portion of the air box and the intake side of the carburetor - don't know if that did much, but there was so much oil/fuel in that area that I thought it couldn't hurt.
There are some videos on the web showing that you need to bend the throttle linkage in several different places, but I found that just bending the forward "hook" of the linkage forward about 1/8" worked perfectly to reach WOT.
Also, since that strange little black filler panel MIGHT have gotten in the way of WOT, I cut out the area just forward of the throttle linkage movement as it approaches WOT - did this with a Dremel. I didn't look for any clearance issues during fitment, but this was an easy modification, so it was done too.
Last modification was to free the exhaust flow a bit. I didn't go crazy, opting to open the vents up a bit with a large flat-blade screwdriver, and then I drilled those same vents with 3/16" drill bit one hole in each vent for a total of four holes and also removed the spark arrestor. Did the muffler mod make a difference? I don't know.
The final step was to tune the saw. Normally I do this with a digital tachometer, but I tuned this one by ear, backing WOT off a fraction of a turn until it 4-stroked a bit, then tested it "in the wood". I had to back the screw out maybe 1/16 of a turn to get the smooth WOT running in the wood and a slight bit of 4-stroking when pressure was taken off the chain.
SAW RUNS BETTER THAN IT DID WHEN NEW! I highly recommend the carburetor change to anyone having issues tuning (or other problems) with a 170, 180, MS-170, or MS-180.
PS: The "Stihl" (Zama) carburetor that came with the saw is marked "China" - discovered that when I could see all sides of the carburetor. Stihl is just not what it used to be, and I was VERY disappointed to see Chinese crap on a Stihl product. Glad most all of my Stihl equipment is 10-30 years old!