stihl ms 660 Carb adjustment???

[DanManofStihl]

Well I just got my muffler back from walkers saw shop and now I am having a few questions. I used to remember how to adjust the carb but for the life of me I am drawing a blank. I have removed the limter caps and I starting adjusting it but I think it is to far out now it is running like crap. So how do I set it back to stock then adjust it to be alittle more rich. Also I am doing this by ear no tach. Any help would be awesome. I did it on my other 066 and it worked awesome but I have forgot in the 6 years ago that I had that saw done.

 

[DanManofStihl]

anybody Btt

 

[blsnelling]

Turn both screws in until they lightly bottom out. Then turn them both out 1 full turn. Warm up the saw. Adjust the low speed needle until you have the fastest idle and then back out 1/8-1/4 turn. Fine tune to where you get the best throttle response. Then set the high speed needle where you're just on the rich side of it going straight 2-stroke. I do this by leaning it out at WOT until it has no 4-stroke at all and back up until its just barely trying to 4-stroke. DO NOT run in that leaned out condition for any extended period of time at all. What I'm talking about doing only takes a few seconds.

 

[weenieroaster]

You may have to re-adjust the low speed again after the high speed. One adjustment affects the other, somewhat.

 

[blsnelling]

I don't thing the H affects the L, but the L does affect the H. That's because it's cummulative as you increase throttle position.

 

[DanManofStihl]

I got out there and messed with it a bit got it running pretty well. Just worried I don't have the low set enough. And wondering if I should be adjusting the idle with the low setting or the idle adjuster? It seems to rev up fine and it idles good I am sure I am just paranoid but it is a pretty expensive saw to just guess on. I asked my local dealer about setting it up for me but his turn around is 2 weeks and would be aleast $35.00 to $75.00 for that I can buy a tach and be done with it but I want it to cut wood NOW.

 

[Evanrude]

I asked my local dealer about setting it up for me but his turn around is 2 weeks and would be aleast $35.00 to $75.00 for that I can buy a tach and be done with it but I want it to cut wood NOW.

Assuming this is the dealer you bought the saw from... He's going to charge you to set the carb up?!?!?!? :jawdrop: :jawdrop: :jawdrop:

I mean, its a $1k saw. He cant just do a simple carb adjustment? And its going to be 2 weeks!?!? I'd get a different dealer...

 

[blsnelling]

You need to find a different dealer. It would take them less than 5 minutes to tune your saw.

 

[DanManofStihl]

All they can see is the bottom dollar. I am sure that if I went in there and they saw who I was it would probably open a few doors. I didn't get that saw from them because I had to have it that day and they didn't stock anything that big but I have bought over 12 saws from them over 7 years a tractor, tons of parts.

 

[Ironbark]

Make sure you have a clean air filter before you start the adjustment.

 

[teacherman]

Turn both screws in until they lightly bottom out. Then turn them both out 1 full turn. Warm up the saw. Adjust the low speed needle until you have the fastest idle and then back out 1/8-1/4 turn. Fine tune to where you get the best throttle response. Then set the high speed needle where you're just on the rich side of it going straight 2-stroke. I do this by leaning it out at WOT until it has no 4-stroke at all and back up until its just barely trying to 4-stroke. DO NOT run in that leaned out condition for any extended period of time at all. What I'm talking about doing only takes a few seconds.

Well put, Brad. Idle speed can be reset with the LA screw after the L and H adjustment are complete, and it will not affect the mixtures at all.

Now I'm wondering if a much longer bar is put on, if the H screw should be reset, because of increased engine load in the cut.

 

[Lakeside53]

Nope... MIXURE is not affected by bar length, but WOT is. That's why tuning to a number is bad unless you use a "medium length" bar, and even that's a rough guess. Just stay slightly rich (4-stroke burble); you'l be safe and cut times won't suffer.


As for the dealer... he's confused between "tuneup" (plugs, filters, carb work as required, airfilters, bars, chains etc) and carb adjust. We run one to two weeks out on "tuneups", but I do carb adjusts "immediately" for free if anyone wanders i.

 

[DanManofStihl]

Man to bad you are so far away. No I asked streight up I just need someone to put it on the tach and set out the carb and he said it would be around 2 weeks. I don't see how any one can have a $1100.00 saw down for that long. I don't run mine pro anymore but when I did two weeks would be a pain if you didn't have another big saw to pick up the slack.

 

[John Church]

Turn both screws in until they lightly bottom out. Then turn them both out 1 full turn. Warm up the saw. Adjust the low speed needle until you have the fastest idle and then back out 1/8-1/4 turn. Fine tune to where you get the best throttle response. Then set the high speed needle where you're just on the rich side of it going straight 2-stroke. I do this by leaning it out at WOT until it has no 4-stroke at all and back up until its just barely trying to 4-stroke. DO NOT run in that leaned out condition for any extended period of time at all. What I'm talking about doing only takes a few seconds.

Hi , I don't think that anybody but an expert would know what a two-stroke would be like when it goes to four -stroke. I am clueless on what you are talking about and I have rebuilt several 911 Porsche engines . Please explain if you get a chance ; I am new to two-stroke small engine repair and trying to learn from experts. Thanks ,John

 

[pioneerguy600]

This is an old thread but I will jump in and try my hand at explaining the four stroke burble sound we look for when tuning a chainsaw. One needs to listen to the exhaust note to hear the transition between two stroke full on power and the drop down to four stroking sound the engine makes when the load on the chain and thus engine is removed. When the carb is tuned correctly the engine will have a slightly rough sound like its missing fire slightly when idling or not in the cut even at full throttle. As soon as the load comes on to the engine as when the chain is now cutting into the wood the sound will change quickly from the rough sound to a full smooth powerful sound called two stroking where the engine is now making full power. When Brad comes along he will post up some tuning video`s he has made that really helps newcomers understand what the terms and sounds mean.

 

[diesel&coffee]

When the carb is tuned correctly the engine will have a slightly rough sound like its missing fire slightly when idling or not in the cut even at full throttle. As soon as the load comes on to the engine as when the chain is now cutting into the wood the sound will change quickly from the rough sound to a full smooth powerful sound called two stroking where the engine is now making full power. When Brad comes along he will post up some tuning video`s he has made that really helps newcomers understand what the terms and sounds mean.

Thanks .. New to tuning and I was not really happy today while doing a basic "learning tune" to my MS660 .. Having read this I fell much better about my idle
May not be totally spot on - but I just feel better about that rough sound at 2700 +/- ... etc etc.. Yes crisp / sharp throttle response and when letting off
throttle it bogs for 3 - 5 seconds.. Learned this is rather correct for having a rich side H screw..

Now I thing I will change out carb gaskets and check the jet size - order a .072 / .074 ..