Saw dies right out of cut. Too lean or too rich?

[rustyb]

Had my saw running good in the cooler spring weather. However, the other day was sawing in temps up to 20-30 degrees warmer (90's) and as soon as I would pull out of the cut, the engine would die.

I assume the low speed adj needs a little tweaking, correct?

 

[Four Paws]

Where in Idaho?

I would do this...start the saw, make a few cuts with it to get it warm. Then, make a good cut at wide open throttle, pull out of the log, and let it rev for about 5 seconds, and shut it down at wide open throttle. Pull the plug, if it is a nice tan color, you're set correct on the high speed screw. Black indicates overly rich, white/grey=dangerously lean!

You might have the carb set perfect, and you just need to increase the idle speed. Better to be rich (1.25 or so turns out) on the low speed screw, than to be lean ( 1 turn or less than 1 turn out). You need to post up some more info - saw type and model, more about when it dies, what the throttle position is, how soon it dies, etc. etc. Hope it isn't the same gas that has been it since winter/spring?!?!?!

 

[rustyb]

I forgot to say what kind of saw. It's an MS260 w/ older fully adj 026 carb. I'll check my plug color next time out. That's what I used to do in my motocross days.

Thanks for the reply.

Oh & BTW. I'm near Twin.

 

[Lakeside53]

Idle is a a balance between the L and the Idle screw and varies with temperature of the saw and intake air. You are likely too rich so turn it a fraction clockwise. The engine may speed up slightly. If the chain moves, turn the the LA screw back slightly until it stops. If the saw then idles too slow, your clutch springs are weak.

Make sure your saw air intake isn't set to WINTER mode - drawing heated air into the carb.

I don't find plug color much of a help for fine adjustment purposes - it is however useful over the longer term to see where the carb was set when developing power (not idling).

 

[rustyb]

Thanks, Lakeside53.

 

[Four Paws]

I'll check my plug color next time out. That's what I used to do in my motocross days.

Oh & BTW. I'm near Twin.

The plug chop is a valuable tool for dirtbikers in our mountainous country - long hill climbs and/or sand dunes can burn a bike down in a hurry. That is why I suggested it.

I don't find plug color much of a help for fine adjustment purposes - it is however useful over the longer term to see where the carb was set when developing power (not idling).

You are exactly right, however a lean plug reading at WOT would indicate a jetting problem. And, although I am not an expert on these tiny diapragm carbs, I know a few things about dirtbike and sled carbs - and, improperly jetted carbs on the main jet can do strange things to the pilot circuit when the throttle is chopped. Anyhow...was just an idea for rustyb to check it. Hope you got that saw fixed up!

 

[Ekka]

Sometimes it can be just a tiny fraction of a turn.

Things do change a little with seasons and how dirty the filter is.

Sometime when things go a bit screwy I carry one of those little screwdrivers with me and keep fiddling throughout the day till I get it right.