Stihl MS650 -- broken -- rebuild?

pantheraba

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Alex and I did a job last week...removed a 60' sourwood for a fellow...got a line drop by the power company, bombed most of it and got it all down...then Alex told the owner he could call the power company to re-attach the line. Then the owner did an add-on asked us to take down a maple near the house...took a bit of rigging on a leaning lead then only had the other 50 foot lead to drop. As I got set up in the last lead I heard the power company truck enter the neighborhood. The top was ready to throw in the precise area where the line was fixing to get raised up again. I checked ropes, tie-in, noted Alex had a good pull on the top and made my backcut. Top went where I wanted it...except as it fell I then saw the 650 on the first stump we had left to cut. We had not had time to completely clean all the other tree debris so the DZ was a bit cluttered.

In all the rush to throw that top before the power company started their work the 650 got left in the DZ. It's a pretty bad feeling to see a top headed towards the DZ and then realize the DZ isn't clear. So...there's my confession. Both of us missed it.

Now, here's the question: Alex took the saw to our Ace Stihl dealer. The damage didn't look too bad. A cracked plastic case and the trigger assembly broken was all we could see...we thought we may have gotten lucky (I saw the bar flex badly when the saw got hit...the dealer said the bar is fine, straight as can be...I guess they have a "memory" and can flex and then go back straight again).

Dealer says the saw needs a new cylinder...that 3 of the cooling fins are broken and if we run it like it is that it may overheat. The repair will be $560....$270 of that is the cylinder/piston assembly. Alex looked online and found cylinder/piston assembly starting at $70 on ebay and $120 at Bailey's.

So....I am wondering if I need to get one of our TreeHouse saw gurus to rebuild this saw for me...or just run it with broken fins...if it does seize up I could get it rebuilt then.

Or is this a good time to get it modded? We don't use it often..usually just to cut a big stump or for final felling of a large spar.

I am open to suggestions.
 
How much use has it?
Age?
Were are fins broken?
If its a good dealer and you get good service I would get him to do it. Good help when needed is hard to find.

The cheaper kits are often good after a bit work. Not always, but often.
 
IMO you can run it. Maybe just be aware that it might not cool as efficiently as a new one so be more attentive to overworking it. Keeping the chain sharp will make it not work as hard on those long, hot stump cuts.
 
Keep the engine clean of build-up to prevent any unnecessary heat build-up. Some saws' fins get really gunked up, like top-handle Stihls.

Picture = 1000 words.
 
I agree with Brian. I'd run it and see. You should be able to tell if it is running much hotter than normal. I wonder how hard it would be to tack on some fins if need be?
 
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  • #7
I was so disgusted I didn't take any pictures. I'll see if Alex can get some when he goes back by the shop.

I know they can help. Thanks for the input so far. My instinct is to run it and see what happens.
 
I have a saw that has been running with a couple broken fins for a couple years. Brian is good input.
Magnus is right about the cheaper kits. I have had hits and misses. Mostly hits. But used the OEM wrist pin clips, bearings and gaskets with the kits.
A top end is pretty damn easy to do..
If I were to pay out that kind of money for a top end rebuilt, I would send the saw out to one of our builders here. I bet that 650 would be a beast if you did.
 
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  • #11
Thanks for the prodding on the pictures. The shop manager is a good friend of Alex...he just sent us pictures. Now that I see the damage we are just going to get them to fix the trigger assy and put it back together. And run it as is.

Thanks for chiming in, guys...good advice.
 

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You know those really hard stump cuts down under the bushes and against the fence where there's no air movement and the hot exhaust is choking you out? Well, the saw is breathing that same hot exhaust air instead of clean, cool air. On those tough stump cuts have your groundman grab the blower and run it while aiming it at the saw starter cover (where the saw draws in fresh air). If he stands in the right spot he can send cool air past your face as well and not blow sawdust in your face. This will allow the saw and you to have a little more oxygen and not get as hot.

This works for all saws, not just saws with broken cooling fins.
 
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  • #13
hahha...what an awesome idea. I LOVE that. I HATE cutting stumps. That might just make it bearable.

Thanks. Here are some picts from the job:
 

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  • #17
In other words, drive it like I stole it!!!

(I still like Brian's way to cool the sawyer...errrr, I mean, saw :D)
 
Prop your blower, let the groundman keep working.

An oscillating sprinkler in dry weather to wet the area, keep dust down can help a lot with grinding. Stumping, probably the same. At least hose the area down, if easy.
 
Prop your blower, let the groundman keep working.
...

Seems most of the time when I get to the stump most of the crew is just standing there waiting for me to finish the cut anyway. It gives one of them something useful to do instead of standing there watching me sweat.
 
I wouldn't be concerned about the broken fins .I doubt it would over heat and even if it does it's going to take a long time before .

You have to remember heat travels from hot to cold .Those fins are right in line from the air blast of the fan on the intake side .They get the first part of the cooling air blast .Vertical cylinder Stihls cool pretty well anyway .
 
I would run that cylinder without any worries. The pic on page 2 cyl.
 
What's the worst that could happen anyways. It could blow and you have to rebuild it? Or just rebuild a perfectly running saw just in case? Naw , run it.
 
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  • #25
That's what I told Alex...I am 64, never had a saw seize up. Might be time to have something new happen.:D
 
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