AlfA01
ArboristSite Guru
My friend's MS230 starting chitting itself in the olive field today. It runs decently and cuts okay (not like the Dolkita EA4300/PS421, but that's a different story altogether). The darned thing just won't idle. Tried to adjust it in the field and couldn't get it right, so I decided to bring it home and have a look.
Here's where I'm at: cleaned the air filter and checked seal around carb inlet, checked the plug (black) and top of piston/cylinder, removed exhaust and inspected visible portion of piston and rings. Now, this is where lies my first question: the rings appear to be contracted quite a bit when the engine is cold. Meaning that the circumference of the piston appears larger by approximately a few thousandths than the rings. Its enough to catch your nail on. Decided to fire it up and see if there was a difference when the engine was warm and sure enough the rings were expanded until they were the same size as the piston. In my book, the rings are shot, but I'm not a Stihl man so that's why I'm hoping someone can chime in and tell me what's up. Definitely appears they aren't creating a good seal against the cylinder walls.
As far as airleaks are concerned, I'd like to rule them out, but at the moment I can't, as I ordered a pressure/vacuum tester and a new compression tester, but they haven't arrived yet. Maybe next week.
Also, the thing isn't responding to idle adjustment until you've really turned in the screw quite a bit. I've got the L jet set pretty good, whereas I think it was overly rich before. It jumps off of idle when you can nurse it in to staying there and revs without hesitation. After returning to idle RPM from revs, it starts to idle then chits itself. Fires right up with first pull, but you have to have your finger on the trigger to bump the throttle to make sure it stays running.
I'm thinking new rings, mic the piston and probably a carb kit. Anyway, on goes the chainsaw saga....
Here's where I'm at: cleaned the air filter and checked seal around carb inlet, checked the plug (black) and top of piston/cylinder, removed exhaust and inspected visible portion of piston and rings. Now, this is where lies my first question: the rings appear to be contracted quite a bit when the engine is cold. Meaning that the circumference of the piston appears larger by approximately a few thousandths than the rings. Its enough to catch your nail on. Decided to fire it up and see if there was a difference when the engine was warm and sure enough the rings were expanded until they were the same size as the piston. In my book, the rings are shot, but I'm not a Stihl man so that's why I'm hoping someone can chime in and tell me what's up. Definitely appears they aren't creating a good seal against the cylinder walls.
As far as airleaks are concerned, I'd like to rule them out, but at the moment I can't, as I ordered a pressure/vacuum tester and a new compression tester, but they haven't arrived yet. Maybe next week.
Also, the thing isn't responding to idle adjustment until you've really turned in the screw quite a bit. I've got the L jet set pretty good, whereas I think it was overly rich before. It jumps off of idle when you can nurse it in to staying there and revs without hesitation. After returning to idle RPM from revs, it starts to idle then chits itself. Fires right up with first pull, but you have to have your finger on the trigger to bump the throttle to make sure it stays running.
I'm thinking new rings, mic the piston and probably a carb kit. Anyway, on goes the chainsaw saga....
