New to me issue - bogs in cut, but doesn't die...

I recently purchased a few 441 Stihls project saws. One of them just needed (or so I was told) the spark plug threads repaired and one or two small odds & ends. This past weekend I finished that one. It fired right up, idled great, revved great, and ran like a beast. I tach tuned it to factory specs. When I went to do some test cutting it did something I've never seen before. It bogged down in the cut, but didn't die; it behaved as if I'd engaged the chain brake; it wanted to spin the chain, but couldn't. It wouldn't die no matter how long I held the trigger, and when I let go it quickly returned to a smooth idle. Pick it up, revved great, back in the wood and a few inches in it did the same thing. I figured behavior like that would only be a slipping clutch. I swapped out the clutch and drum from another saw and had the same result. It doesn't seem to act like it's a carb problem, but just to be safe I pulled it off and did some housekeeping. The two primary suspects I've seen in the past (screen and metering lever height) were fine.

Anyone else ever run into this problem? I ran out of time, but hopefully later this week will swap the carb out for one off another saw. Carb? Clutch? Some other strange part from this saw-of-a-million-pieces???

Thanks!

 

Alright, this will sound so simple, maybe stupid but is the chain oiling up good and clearing chips out?? Really doesn't seem like a motor problem...btw are these 441's mtronic or standard carbs?

 

My 261c kinda acted this way when i sunk the 18" bar with a subpar chain into a dead and dry 26" oak stub...i like to keep the chain nice and tight, maybe too much sometimes, but I know going too loose on the tension and you wear out the guide bar faster, although you would think it would be the other way around. Madsen's website is my source on the proper chain tension btw. Anyway I looked at the drive links and they were bone dry. I took off the bar, cleared the oiling holes and readjusted my chain. Problem solved.

 

I also gotta say a masterminded 261c with a sharp chain throws chips like no tommorrow. When I'm cutting on a stump it likes to plug up, and I clear it by revving the saw out of the wood regularly. Especially when you go beyond the bar length, which I do quite often lol

 

Kinda basic thing here NewToStihl that I'm talking about but it's just something simple like this has tripped some guys up. Not saying you don't know how to work on or operate a saw here whatsoever.

 

Yes, oiling correctly and clearing chips fine. Actually, I'm not even getting far enough into the cut to build chips up. Standard carb models

Before testing any saw I clean the groove in the bar and put a fresh edge on the chain. Chain is tensioned correctly too.

No offense taken - I appreciate all feedback and suggestions! Sometimes the simple things are easy to overlook.

 

How's the compression?

 

Unless the chain has some damaged drive links, or the drive sprocket is absurdly worn, or the chain isn't actually engaged in the sprocket, then the clutch simply has to be slipping. That's not to say that there's anything wrong with the clutch.

I'd try swapping in a different bar and chain to see whether that makes a difference. Divide and conquer.

 

It's good - a little over 150 psi

Good call, better safe than sorry. The sprocket shows minimal signs of wear, so the next time I get a chance to head out to the shop I'll definitely try a different bar & chain.

 

Why would a slipping clutch cause it to bog...should be the opposite...no?

 

Yeah, "bog" is an imprecise term but what I think what NTS is saying is that the engine keeps running but the chain isn't moving. That's why he and I both concluded that the clutch is slipping. "Bogging" is more often used to mean loss of engine power, but I don't think that's what's going on here.

 

Yes, to clarify, the chain stopped and the engine RPM dropped dramatically, but not in a choking/stalling manner. I should have just said it's 'hanging up' in the cut, almost like you'd experience with an under-powered saw. A 441 on the other hand should obviously be able to make quick work of 12" pine...

 

How's your chain? Specifically, is it too aggressive?

 

If it were the air filter, wouldn't it just stall the engine when the chain stopped?

 

I was thinking screen in the carb as well. Said thats fine. Also like jon said I have had problems when a chain had worn drive links from being thrown they bind in the bar. Bit if it spins wide open out of the cut that cancels that idea.

 

Low rakers?

 

1. Check chain (see above)
2. Replace carb with known good carb and check tank vent
3. Check air filter
4. I had this problem with an 029Super that never really ran "great" from factory and now has an AM p/c after a scored piston. It'd tune great out of the wood, no racing, no signs of air leak. Once in the wood, it would run for a split second, then bog and drop in rpms. I switched carbs; no dice. Thought it was a stuck ring... it wasn't. Finally I gave the crank a wiggle... bad clutch side bearing! Very subtle, but not tight. During tear-down, we saw where we think the bearing was bad enough to mess up the seal. The RPMS didn't race (like a normal air leak), but the dang thing wouldn't cut! Finally I got a Hutzl short-block and put that on with some caber rings. She's a good runner now.