MS361 Arctic woes...

Tjwb

New Member
Joined
Feb 18, 2021
Messages
3
Location
Canada
Hey guys, been lurking around here for a little bit!
So I've picked up this MS361 Arctic a little while back, owner said it would run but wouldn't idle.
I dug into it, muffler and stuff was falling apart, screw holes stripped out on the cylinder. Two deep scores toward the bottom of the exhaust side of the piston (about 1/4" to 3/8" long), each kind of inline with the edge with the outer edges of the port. Fairly heavy carbon build up on top of the piston and in the exhaust port.
Got it running, sure enough doesn't want to idle, if you get the rpms up a bit it gets snappy and crisp but bogs out or dies when you let off.
Picked up a carb kit, cleaned the carb and put it back together, new pick up filter. Could finally get it to run and half assed idle, seems rough- shakes alot, doesn't have the ting-ting-ting you'd see and hear on most saws. Boggy off idle, but if you feather the rpms up its fairly crisp and revs out well.
Bought a meteor piston/caber rings, installed that today and cleaned up the cylinder, couple small marks low on exhaust side that would have matched up with the old piston. No better after install, maybe worse for the first while, finally got it to idle again but everything else remains the same. Can't seem to find any air leaks. It will fire up on half choke and run most of the time but sometimes dies out, don't think it's a lean condition because if I give more on the low side it won't start or won't idle at all. Only seems to want to run if it's 1/4 throttle or more.
Tried a different coil, reset the gap, new plug, played with the carb alot, no changes really. It either won't start, won't idle or will start and idle ruggedly and be boggy off idle until you feather the rpms up. It cuts.
I also find it weird that starting factory settings on the carb are 1/4 on the low side and 3/4 on the high side lol I've been trying to stay around 3/4-1 full turn on the low and 1 turn on the high.

Any ideas? I'm not sure what has been touched before I dug into it but everything appears as normal.
 

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lone wolf
Joined
Oct 5, 2009
Messages
61,108
Location
Prowling The Pine Barrens
Hey guys, been lurking around here for a little bit!
So I've picked up this MS361 Arctic a little while back, owner said it would run but wouldn't idle.
I dug into it, muffler and stuff was falling apart, screw holes stripped out on the cylinder. Two deep scores toward the bottom of the exhaust side of the piston (about 1/4" to 3/8" long), each kind of inline with the edge with the outer edges of the port. Fairly heavy carbon build up on top of the piston and in the exhaust port.
Got it running, sure enough doesn't want to idle, if you get the rpms up a bit it gets snappy and crisp but bogs out or dies when you let off.
Picked up a carb kit, cleaned the carb and put it back together, new pick up filter. Could finally get it to run and half assed idle, seems rough- shakes alot, doesn't have the ting-ting-ting you'd see and hear on most saws. Boggy off idle, but if you feather the rpms up its fairly crisp and revs out well.
Bought a meteor piston/caber rings, installed that today and cleaned up the cylinder, couple small marks low on exhaust side that would have matched up with the old piston. No better after install, maybe worse for the first while, finally got it to idle again but everything else remains the same. Can't seem to find any air leaks. It will fire up on half choke and run most of the time but sometimes dies out, don't think it's a lean condition because if I give more on the low side it won't start or won't idle at all. Only seems to want to run if it's 1/4 throttle or more.
Tried a different coil, reset the gap, new plug, played with the carb alot, no changes really. It either won't start, won't idle or will start and idle ruggedly and be boggy off idle until you feather the rpms up. It cuts.
I also find it weird that starting factory settings on the carb are 1/4 on the low side and 3/4 on the high side lol I've been trying to stay around 3/4-1 full turn on the low and 1 turn on the high.

Any ideas? I'm not sure what has been touched before I dug into it but everything appears as normal.
Did you vac and pressure test? Test the compression and tell us what it is. Are you sure the mounting screws for the cyl are holding?
 

Tjwb

New Member
Joined
Feb 18, 2021
Messages
3
Location
Canada
I've had the cylinder off twice, seems everything is solid and sealed- visually and by feel, that is. I dont have a compression tester yet but prior to new piston and rings the damn thing would rip a small child's arm off from compression on the rope- after replacing and the rings set in, same. I'm gonna say it's safe to say it has compression well within spec.
I haven't vac tested yet, I'll need to make some block off plates and then go from there.
I've sprayed all around everywhere while the saw is running to see if there's any change in idle or rpms, nothing.
I'm wondering about the coil, it seemed like it ran worse with the used coil I put on it, installed the original again and it ran better but the same as it did, obviously.
 

Tjwb

New Member
Joined
Feb 18, 2021
Messages
3
Location
Canada
*Update- so I see the site has been fixed and this old post came back! Not sure where my replacement post went now lol
Anyway, as said in the other post I found the problem for anyone wondering- flywheel key was broken and timing was thrown off. Retimed and torqued the flywheel down and the saw runs like a top!!
 

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