MS660 won't idle

[nate379]

I bought an MS660 a little while back and I can't get the thing to idle. I have the carb screws all the way down and it's still spinning the chain on a 34" bar fast enough I can cut wood! When I first fired it up it was idling close to WOT though so I guess that was some improvement.

I ended up dropping it off at the saw shop since I don't have time to screw with it (I'm making the seller pay for the repairs, he sold it as a perfect running saw).

Just wondering if anyone has an idea on what is going on with it? The throttle isn't stuck or anything like that.

 

[thewoodlands]

Stupid question, what about the idle screw?

 

[lukem]

Air leak?

 

[NH_Wood]

Was going to suggest bad clutch springs for the spinning chain, but sounds like something different here - adjusting the idle screw has no effect at all? Cheers!

 

[ScotO]

For starters, why do you have the carb screws the whole way down? When setting up a saw, each screw should be turned down the whole way, then BOTH of them should be backed out 1 to 1 1/4 turns. That's the starting point to getting them tuned up. When you have the "L" screw turned the whole way down, you are leaning the idle the whole way off.....when the "H" screw is turned the whole way down, you're leaning out full throttle........when the saw is running really lean at idle, it will spin the chain.

If you do the above and get your initial settings like I said, you should get it to start up. If it's turning the chain when you start it up with those initial settings, you need to richen the "L" screw until it stops.....if you do richen the "L" screw and it continues to run the chain, you got a crankcase leak or a plugged-up carburetor......

 

[BrotherBart]

Stay away from screwdrivers and two stoke engines.

 

[ScotO]

Stay away from screwdrivers and two stoke engines.

 

[nate379]

Idle speed and idle mixture. Turned all the way down to slow the idle down, which it's not doing very well. I got it down from near WOT to maybe 1/4 throttle and that's it.

For starters, why do you have the carb screws the whole way down?

 

[ScotO]

Idle speed and idle mixture, 2 screws.

Actually there are three screws......your idle speed, your idle mix and your high throttle mix.......

Why would you have both idle and idle mix screws turned in the whole way?

May be time to follow BB's advice here....

 

[nate379]

In case you didn't know, I'm a ASE certified mechanic in automotive and heavy equipment I've been working on this stuff for over 15 years.

I don't work on many saws so I can't tear them apart in my sleep like a few guys on here. I spent about 5 mins trying to adjust it. Like I said, I don't have time to screw with it, so I dropped it off. If it's not running right it's not making me money and that's what matters.

It was pouring rain today so I got caught up a bit on some repairs instead of cutting wood. Right now I have a Bobcat half torn apart, putting new cylinder seals, bucket repairs, oil change, filters, etc. Also have a dumptruck that I'm doing repairs to the dump bed. Would also need to pull my trailer in to put a new axle under it (only did one last year, didn't have time for the other), and put a new bearing on the fan mount on another truck... but only so much room in the shop.

How's your foot taste?

Stay away from screwdrivers and two stoke engines.

 

[BrotherBart]

Three screws. L, H and LA for idle. LA contacts the throttle shaft to set the idle.

 

[ScotO]

I work on diesel locomotives, some very complex equipment in those puppies.....
And I can tell ya, I've had those little chainsaws baffle the chit out of me more than once.....usually ended up being a crankcase issue.

But I've NEVER turned the idle and idle mix screws down the whole way and expected it to run properly, either......

 

[BrotherBart]

ASE and A&P here. Hope the guy that knows how to tune it gets it done.

 

[nate379]

I was talking about the screws that I turned down.

Actually there are three screws......your idle speed, your idle mix and your high throttle mix.......

Why would you have both idle and idle mix screws turned in the whole way?

May be time to follow BB's advice here....

 

[ScotO]

No freaking chit, I was talking about the screws that I turned down. Are you really this stupid or just being a TROLL?!

Pink cat with a blue face and your calling me stupid? No, not a troll either bub...
Actually, you are the one who asked the question......I tried to help out a little and you flipped your cake. If you tune cars like you tune your saws, remind me never to use you as a mechanic.......

No need to be a D*CK. I'll skip trying to help you out in the future. Get a life.

 

[DexterDay]

I'm guessing by closing the L screw all the way? You mean as far as the limiters will let you?

Because if there is no limiter caps, then the saw wont run? Period.

Sounds like the mixture on the L (and idle). MasterMech had a food video describing how to set the carb. Some other decent videos out there. Not super hard. A tach is almost a must for setting H, otherwise roll on the side of caution and run a richer H (more four stroking). That 460 should turn 13,500 RPM when tuned proper up top.

 

[TreePointer]

bad carb
air leak
bad clutch springs

Time to take bets? Winner gets a left handed smoke shifter for the wood burner.

 

[bogydave]

I ended up dropping it off at the saw shop

Sounds like a good idea

 

[343amc]

Last 2 stroke engine I had that acted that way ended up having a failed crank seal.

 

[mikefrommaine]

IBTL

 

[HittinSteel]

If you turned the idle screw all the way in, which would be clockwise, you have actually turned the idle up to MAX........which would explain why you can cut wood at idle.