ms180 frankenstein build

[Redbeard343]

so i was reading on this forum (its a pretty old one https://www.arboristsite.com/threads/ms180-adjustable-carb.74899/) and i have a little experience with chainsaws. have a poulan pro 42cc and a free ms180 that so far ive put in $16 for a new engine and piston. ran great for a year and a half but lately it just bogs whenever i go full throttle, or sort of "revs" itself. I have a muffler mod and intake manifold mod (plastic cover the air filter sits in, pre-filter is modded) and ive got a couple amazon carbs that came with the saw. just recently started thinking i wished there was some sort of adjustable carb then came across that article and found this guy https://www.amazon.com/Carburetor-STIHL-Chainsaw-Replaces-C1Q-S84/dp/B06Y5FMVHS can i swap a ms250 carb onto my 180 with just some parts swapping from the old carb to get the new carb hooked up? been on a tight budget and its either this or getting some chains for the poulan, which currently runs like crap since i got it from my grandfather and it mightve last ran before i was born, been pretty rough and might need a carb if i run it hard but i got it running. Thanks, my first post btw but ive been a lurker for a couple years.

 

[Michael E]

There are chinese adjustable carburetors out there for about 10$ that should be a straight swap.

If your saw suddenly changed behaviour, you might first find out what caused it. Just throwing a carb at the saw might fix it... or not...

 

[Redbeard343]

well the hoses are all recently new, as in a year old new, ive only ever used stihl premixed gas and when it sits i run it out of fuel, air filter and spark plug look good and after pulling the muffler and carburetor i cannot see any marks on the engine. my rebuild used the old crankshaft and it didn't look bad but i had some really bad wear on the old piston and cylinder so those were replaced. i worry about the old crankshaft but there was some fuel i used abouta month ago that was suspicious, mightve been old but was within the timeframe of usage from stihl. so idk, i dont really throw parts at things unless im stumped, and i don't have the equipment to test the vacuum of the tank and lines but it doesnt leak any fuel and the valves are as new as the hoses and clean/free from dirt.

 

[stihltech]

Do a poor man's vacuum test. Get a spray can of brake clean (or carb cleaner). Spray around anywhere there is a seal, hose, case sealant, carburetor mounting, etc.
If it changes the idle, yo have found a leak.
All the hype about the adjustable carburetor will not cure an issue elsewhere in the saw. And that is usually where the problem lies.
Got to verify the rest before getting parts. I have cleaned those carbs a back probed passages to get rid of bogs. Inlet lever and main jet have to be clean. Set idle as rich as you can without stalling. Remember, backing out the 1 screw richens the idle.

 

[Michael E]

When you changed piston and cylinder, did you change the crank shaft seals? And if so, did you use quality parts? Because when those start to leak (draw in air), that will wreck your engine very quickly.