Problematic MS661

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mcobb2

mcobb2

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Look under the FS 38... I used to rip the stickers off. Hurt my fingers so I just quit promoting them. Sticker says "Made by Stihl in China" or something really close to those lines.
 
David Young

David Young

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Brad,
I think you have a great scientific method going on here, nice job.
the thing I may offer to you while you are looking for answers is this.

think a little out of the box too. could a tank vent or a marginal crank seal cause a problem, iffy base seal. just offering out of the box thoughts. likely it will be in the carb itself that seems the most likely.
 
blsnelling
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think a little out of the box too. could a tank vent or a marginal crank seal cause a problem, iffy base seal. just offering out of the box thoughts. likely it will be in the carb itself that seems the most likely.
Great point. I've considered the possibility of an air leak. You wouldn't expect it on such a new saw, but stranger things have happened.
 
procarbine2k1

procarbine2k1

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It was pointed out to me by a fish once that i bought a chinese knockoff of a chinese made zama carb ,so the chinese are making knockoffs of their own product now .

Zama also makes carbs without their name cast in them, if it infringes on an agreement they have standing with a manufacturer. I normally don't buy a lot of AM parts, but the AM carbs I have seen and used have been great.
 
blsnelling
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Next I have to determine the source of the problem. Since his is running perfectly, I'm thinking I'll put my parts on his saw, one at a time.
The more I think about this, the more I think I'll put all the mods back on my saw and work from there. The first thing I'm going to do is a pressure/vac test. After that, I'll swap the complete carb, and go from there.
 
David Young

David Young

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its yours to do what you want with, my thought is to continue putting parts on the good saw until its not good any more. sometimes while tearing it apart you find the fly in the ointment remember your solo twin with the backward piston.

i know it it a new saw and should't have issues but. its there and real.
 
nitehawk55

nitehawk55

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Have a close look at the throttle plates on both carbs and see if there is any difference in them . My husky dealer had a 562 that was bogging and the throttle plate design was a bit different in the new one and it fixed the problem .
 
blsnelling
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Have a close look at the throttle plates on both carbs and see if there is any difference in them . My husky dealer had a 562 that was bogging and the throttle plate design was a bit different in the new one and it fixed the problem .
Will do. They made a LOT of changes to the 562 carb! I think it took them four tries to finally get it right.
 
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