Stihl MS441 Mag Rebuild

[Cody]

Buddy brought over his 441 yesterday afternoon, couldn't get a complete turn out of the flywheel. Pulled the plug and looked like it was running pretty lean. He was running mix fuel and had just been running it that morning, never noticed any problems until he went to refuel it and it wouldn't pull over. This saw has a lot of use on it, summer time use in the heat and I know it has lived it's life running lean as it's a screamer. I always said we should fix that but the response I got was it runs fine. Not a whole lot of pictures included as we were busy trying to tear it down with no IPL or SM. I believe the route we're going to go is aftermarket P&C, meteor kit most likely unless the NWP big bore kit is a better idea, obviously open to advice on that. I'll try talking him into OEM wrist pin, bearing, and clips. I don't "think" that the crank seals are bad but bad idea not to change them while we're in there. The lower rotating assembly feels good as well, a lot of crap down in there and after soaking it once it needs more cleaning IMO. OEM is $300-350, and we discussed that if he's spending that much that it would be wise for a total rebuild, so without knowing 100% that the bottom end is good that's why he's going on the "cheap" end for P&C. In his words the saw doesn't owe him anything. I believe the saw failed just from years of running lean, and the decomp valve sure looked suspect. I told him they all seam to leak a bit and we're thinking of plugging that. Advice would be greatly appreciated, gotta talk him into at least opening the muffler and removing the limiters.


Will document the rebuild much better than the tear down as well.

 

[user 122190]

Good project. AM at 1/10th the cost of P&C kit is the way to go. At the price of OEM, might as well just buy a new saw.

 

[K Mueller]

Are the cylinder fins packed with as much crud as the rest of the saw

 

[kenton.a.frank]

I have a 441 arriving today where the piston looks very similar to that one with the chunk missing. I bought a Hyway BB kit im going to try for a personal saw. Might see if I can open the intake and the exhaust just a bit. Goal being to make it worth the weight to lug around. Keep me in the loop on what you end up doing!


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[Cody]

Good project. AM at 1/10th the cost of P&C kit is the way to go. At the price of OEM, might as well just buy a new saw.

Yeah, at 3-400 he figured it was better to go towards a new saw, joked with him that I know where there's a 461 still sitting on a shelf. He's had a 362 on his mind lately but we'll see how this goes.

Are the cylinder fins packed with as much crud as the rest of the saw

No comment....just kidding, cylinder wasn't nearly as bad. The saw has lived a rough life, I'm sure he would have thanked me if I'd have just removed the limiters and tuned it right. I feel somewhat to blame but, not my saw. I think he's pretty excited to get it cleaned up and back together. Told him he needs to bring it to me once a year to tear down and clean it!

I have a 441 arriving today where the piston looks very similar to that one with the chunk missing. I bought a Hyway BB kit im going to try for a personal saw. Might see if I can open the intake and the exhaust just a bit. Goal being to make it worth the weight to lug around. Keep me in the loop on what you end up doing!


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The broken piston skirt was definitely something to see! I'm not going to attempt any sort of porting, I think he'd be happy with a tune and mm. 441's are a dream to run, but I think I'll pass on owning one. Total pain in the ass to tear apart, mainly due to the carb set up, throttle cable isn't too much of an issue.

 

[user 122190]

Total pain in the ass to tear apart, mainly due to the carb set up, throttle cable isn't too much of an issue.

Lots of parts in a small space. Almost 2lbs of poop in a 1lb poop bag.

 

[dmb2613]

441 not bad to work on

 

[Cody]

Lots of parts in a small space. Almost 2lbs of poop in a 1lb poop bag.

Carb and intake boot were definitely different, the rest wasn't too bad. Always fun to tear in to something new, but I'd rather not have to.

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[kenton.a.frank]

Finished mine tonight. Pleasantly surprised. I’ll test cut and time tomorrow vs a regular 441.

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[Cody]

Finished mine tonight. Pleasantly surprised. I’ll test cut and time tomorrow vs a regular 441.

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You do a rebuild with OEM?

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[kenton.a.frank]

You do a rebuild with OEM?

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No I had a spare Hyway big bore sitting around from a customer that wanted it but changed his mind when his saw was salvageable with some cylinder cleaning and a meteor pistons I’m not out anything if it falls apart.


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[Cody]

Short update, he bought a standard bore meteor kit. Pretty impressed with it, port shapes and finish was just as good as OEM. We didn't take pictures while assembling, these saws are complicated to assemble, especially not remembering what goes where and in what process. Came with the correct factory plug as well, used the base gasket and everything that came in the kit along with a new OEM wrist pin bearing. He put the muffler on it already so no mod as of yet though I did pull the screen out, and trimmed the tabs on the carb so we can set it at 13,500. I'll probably set it rich for break in, hopefully have it running tomorrow as it's not fully assembled yet.

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[Maintenance supervisor]

No I had a spare Hyway big bore sitting around from a customer that wanted it but changed his mind when his saw was salvageable with some cylinder cleaning and a meteor pistons I’m not out anything if it falls apart.


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How's that bb ms441 doing?