066 winds down slowly

[Tucker943]

I have an old 066 that I like. Ive been thinking about selling it and buying another husky big saw, but thats a whole different story. Anyways, when youve been running it, and let off the throttle, it seems to bumble back down slower then it should. Once its warm, the throttle wants to stay higher then idling rpm. I took it to the nearest stihl dealer and they set the high low screws right in front of me. But when Im on a job and the saw is getting a good workout and I let off the throttle, the same issue........?

 

[SkwerI]

Running lean and getting hot. Playing with the carb can mask the symptoms but doesn't address the root cause. Possibly an air leak somewhere. When was the last time you gave it a good cleaning and brushed off all the cooling fins?

 

[Tucker943]

I bought it and only have a few hours use on it. It was clean when I bought it, and still is.

 

[forestryworks]

Sounds like an air leak to me. Betting on seals.

Do a pressure and vac test.

 

[Al Smith]

Sounds more like a torn boot .They can can get stetched from an up cut and you can't tell it by inspection through the inside with the carb removed .The Rocky special 038 Mag did the same thing when I unknowingly had broken the top motor mount .

That pot licker would really rev up though .Now had I continued running it that way it would have cooked the piston and that would have been a very sad day indeed .

 

[Tucker943]

I don't have the tools to check vacuum. I'll just have to take it to the dealer again.

 

[MasterBlaster]

I have an old 066... that fugger (after a rebuild) Rocks and Rolls!

 

[Al Smith]

As a general rule the older ones will out perform the newer 660's .

 

[Burnham]

Easy to fix, Chris...just tighten the chain way too tight. It'll spool down fast then.

 

[Cut4fun]

Sounds more like a torn boot .They can can get stetched from an up cut and you can't tell it by inspection through the inside with the carb removed .The Rocky special 038 Mag did the same thing when I unknowingly had broken the top motor mount .

This is something I have noticed too with the design of the pro stihl saws and the older metal cased poulans. The intake boot goes through the tank area and abuse from the operator can rip the boot unknowingly.
For this reason I really appreciate the design husky has on their 362 365 372 346 etc.

 

[Al Smith]

Here's what actually happens if you think about it .With a tear in the boot even with the throttle closed you get a giant venturi effect on the low speed jet which is below the throttle plate .With a closed throttle plate it effectively acts much like a choke plate and you draw a hell of a vacuum over the jet .

I kid you not that 038 would wind up to I'll bet 10,000 rpms with the throttle completely closed .I wouldn't have thought the low speed jet could allow that much fuel through but it can .

With a leaky seal you usually just wind the saw up running thin or it just dies out .It could be a seal I suppose .Another one of those internet guesses that could be completely incorrect .

 

[Tucker943]

Ill drop it off this week and announce the verdict. No time to mess with it myself. Im firing the wood processor up tomorrow night and dont intend on getting off of it for a VERY LONG TIME.

 

[woodworkingboy]

I find that some of the saws will wind down slowly with a too lean setting on the low speed adjustment. It seems like it is more at the end of the wind down though. Possibly the too lean setting is a compensation for a carb problem.

 

[Al Smith]

I can't neccessarily say that rough housing is what stretchs the boot and breaks the mounts is the real cause or not .It's just something that could happened .

Idealally a saw man or woman would pay more attention to such things but in the real world it more times than not is not even thought of until after the fact .Things happen .