MS661 issues

[islandguy]

Hi all,
I'm new to milling. I picked up an MS 661 with about 80 hours on it. Started milling cedar a couple months ago and it worked great. Got back to it this week and the saw was laboring somewhat through the cuts (with a freshly sharpened chain) compared to last time. On my third cut it was struggling and made a loud popping noise before I shut it down.

It has since sat for a couple days and starts fine, runs fine at full throttle but I don't want to put it back on the mill until I figure out the problem. One thing is that it does spin the chain when idling. Not much experience with saw maintenance. Any thoughts on what the problem might be?

Thx

 

[ammoaddict]

Broken clutch spring or debris packed in the clutch keeping it engaged.

Sent from my moto g(7) power using Tapatalk

 

[Walkdog]

+1 on starting with the clutch. If that doesn’t fix it you’re probably looking at an air leak and a more significant repair.

 

[mememe]

Change the spark plug, only use NGK BPMR7A. Could have been unburnt fuel that went pop in the exhaust. Clean the air filter. Were there any mods to the saw? Premium fuel and premium mix, never the cheap stuff. Keep the clutch cleaned as above mentioned and an air leak at the carb boot will cause a lean condition. Milling chain will make the saw cut better. Don't shut the saw down right after milling, allow it to idle and few revs will help cool it down.
I mill with a fully modified MS880 and I don't push the saw too hard. Patience is better than kaboom.

 

[cscltd]

I have seen plug boot come off spark plug and or spark plug come loose on these when working hard under load a few times and causes popping sometimes

 

[lone wolf]

Pull the muffler off and see how the piston looks, post pics here.