Need a little advice...40:1 to 50:1

[USMC615]

Hey folks, hope all are doin well. In a nutshell...buddy of mine gave me a Craftsman 40cc, 18" saw over a yr ago. I believe its about 10 yrs old, black and red in color, got case and all with it. The logo on the bar isn't even a quarter gone, basically never used. I offered him new money for it, he was goin through a divorce and he would have nothing to do with it...he said if I didn't take it, off to the landfill it went...she bought it for him. Anyhow...before everyone says make a jon boat anchor out of it and be done with it, I dug it out from the 'back 40' in the shop yesterday and started breaking it down. I ran carb cleaner through the butterfly, let it set for a few mins, dumped it, repeated the same. Cleaned plug with gas, small wire brush, cleaned air filter, etc. I put 50:1 in it, of course treated with star-tron, as is all my pre-mix, and cranked it. Had to crank the idle-T up a round or better to get it to a nice idle, nothing over-revving.

After lettin it set for a few minutes idling, when I gave it fast trigger gas, it wanted to bog. Let it set idling longer, now it gets a little more responsive, but still wants to bog about 1/5 of the throttle range, and have to be slow on the gas giving, then it takes off like a scalded dog and runs ok.

Do I need to fool with the 'L' or 'H' on this thing? I don't wanna hit or miss with it, just wanna see it be responsive at all trigger pull without the 'bog' effect or letting it idle for a few/several minutes before use. It's lightweight, will make a great limbing saw if nothing else. I know they're threads on this 40/50:1, read a few, but they seemed hit and miss about it. If ya don't mind, like your take on it. Thanks fellas.

 

[USMC615]

...and I apologize, i shoulda put this over in the chainsaw thread. I'll try to figure out how to move it.

 

[greenskeeper]

bogging would indicate a carb adjustment on the hi end

 

[USMC615]

bogging would indicate a carb adjustment on the hi end

...need to back it down some...too rich running, stepping it up to 50:1?

 

[zogger]

If it sat up for awhile with old fuel, who knows. Sometimes I have found a day or two after a resurrection the internal carb diaphragm seems to get a bit more limber and respond better. If anything, bog from idle to wide open throttle, try more L counterclockwise, richer.


The worst probably is just a new fuel filter, carb clean and kit of gaskets, fuel line, purge return line, bubble.

Also clean the air filter and remove muffler and check for obstructions (sometimes you find mud daubers have moved in..) or a dirty carboned screen. If the screen is clogged, you can burn it off with a propane torch easy.

 

[USMC615]

If it sat up for awhile with old fuel, who knows. Sometimes I have found a day or two after a resurrection the internal carb diaphragm seems to get a bit more limber and respond better. If anything, bog from idle to wide open throttle, try more L counterclockwise, richer.


The worst probably is just a new fuel filter, carb clean and kit of gaskets, fuel line, purge return line, bubble.

Also clean the air filter and remove muffler and check for obstructions (sometimes you find mud daubers have moved in..) or a dirty carboned screen. If the screen is clogged, you can burn it off with a propane torch easy.

Yeh, I checked for any dirt dauber signs, etc. and no trace of any. Under the housing this thing looks brand new. I remember him telling last time he cut with it, he drained the gas/mix out completely and even pulled the plug, poured a little in the cylinder and pulled the starter rope slowly several times. I did pull the fuel filter and sprayed it real good with carb/choke cleaner as well, and the fuel lines all look brand new. Primer bulb works perfect. When I gassed it up yesterday with fresh 50:1, I also added a few little capfuls of sea-foam in the tank as well, try to burn any deposits or gummed up crap in the carb out. I wouldn't think there'd be that much if any since such little run time with this saw in its lifetime. The muffler/screen looked like new basically.

Reason I'd like this saw to run smooth on 50:1 is everything else; three other saws, weed eaters, blowers, etc all run 50:1. I've even got an old 32cc blower and an old weed eater that ran 32:1 and they have ran fine over the years at 50:1, just slight idle adjustment was all they needed. Good response through the entire throttle range with them. I don't want to have to keep a couple different ratio mixes around, especially when the non 50:1 mix(es) won't get used up near as quick as the 50:1. I'll play with the saw again later today and like you said, maybe just needs a little more run time, may need a slight L richness adjustment.

 

[blades]

keep running the seafoam and it will clean up response wise just takes several applications. ethanol vs the carb- either rebuild carb or replace it if you want to get around the problem faster. Sometimes even rebuilding carb does not resolve this due to ethanol effects - metallic carb parts get oxidized by ethanol ( even stored dry) jams up some of those tiny passages that you can't even get to. I am not a small engine person but I do dable in these things when forced to - the seafoam works pretty well for me.

 

[Whitespider]

If you had to crank the idle up to get it to idle, and throttle response is hesitant or sluggish, it sounds like a lean condition. "Lean" may be caused by the carb... but it may also be a vacuum leak, in which case workin' on the carb won't fix owl squat. If the saw has been sittin', and especially if ethanol blended fuel was used in the past, dried out or hardened seals and gaskets may be the issue. I've also seen where small two-cycle engines have been stored after using an ethanol blend, and the resulting corrosion eats pin-holes through the case.
*

 

[stihly dan]

in which case workin' on the carb won't fix owl squat.

In this case it should be pretty easy.... cause the owl squat is not cold or sour.

 

[svk]

I've run anything from 32:1 to 50:1 in my ope. Normally 32:1 because a little extra oil is cheap insurance. If you are running a high performance saw it is much more important. For a stock saw not so much.

Try adjusting your H and L settings one at a time. If that doesn't work take the carb apart and and clean it up and then try to tune again. If that also doesn't work you need a carb kit.

 

[sunfish]

bogging would indicate a carb adjustment on the hi end

No, bogging off of idle means it is lean on the (L) low side.

Turn the L screw counter clockwise a quarter turn and report back.

 

[USMC615]

I just ran it for about an hour or so and had to back the idle-T down about a turn, revving a little high at idle and chain rotating a little...seems I've had to undo the clockwise turn I gave the idle -T yesterday. I think maybe between yesterday running the tank with a few capfuls of sea foam and today as well with sea foam may have burned through some gummed up deposits or something and the jets/needle valves have possibly opened like they should be. Giving it wide open throttle real fast from a standing idle seems to be much better as well. It may work itself out...gonna run another half tank or so with another good shot of sea foam in it again here in a little. Hopefully the bugs work themselves out with a little sea foam help and not have to get inside it. Got great power on the top end, runs good and doesn't miss a beat. Same for deceleration of WOT returning to a sitting idle.

I know one thing, it sure pumps some bar and chain oil...it ain't lacking a bit in that department. Of course it's non-adjustable. Don't know if that's common for Poulan/Craftsman saws or not. I'm running Echo Premium bar and chain oil in it.

 

[sunfish]

I know they're threads on this 40/50:1, read a few, but they seemed hit and miss about it. If ya don't mind, like your take on it.

I run 32:1 in all my two stroke stuff. 40:1 is good, 50:1 is OK too... It ain't that big a deal.

 

[svk]

I just ran it for about an hour or so and had to back the idle-T down about a turn, revving a little high at idle and chain rotating a little...seems I've had to undo the clockwise turn I gave the idle -T yesterday. I think maybe between yesterday running the tank with a few capfuls of sea foam and today as well with sea foam may have burned through some gummed up deposits or something and the jets/needle valves have possibly opened like they should be. Giving it wide open throttle real fast from a standing idle seems to be much better as well. It may work itself out...gonna run another half tank or so with another good shot of sea foam in it again here in a little. Hopefully the bugs work themselves out with a little sea foam help and not have to get inside it. Got great power on the top end, runs good and doesn't miss a beat. Same for deceleration of WOT returning to a sitting idle.

I know one thing, it sure pumps some bar and chain oil...it ain't lacking a bit in that department. Of course it's non-adjustable. Don't know if that's common for Poulan/Craftsman saws or not. I'm running Echo Premium bar and chain oil in it.

Good to hear it cleared itself up.

My 65 commonly needs a turn up on the idle after it sits for a while and after a few tankfuls it needs to be turned back down.

 

[USMC615]

Good to hear it cleared itself up.

My 65 commonly needs a turn up on the idle after it sits for a while and after a few tankfuls it needs to be turned back down.

...still a little hesitant/bogging from idle to real quick WOT, but not as bad as yesterday. Don't have to baby it quite as slow initially on trigger pull. I'll see what Sunfish's advice does on backing off the L about a quarter turn here in just a little bit.

 

[sunfish]

...still a little hesitant/bogging from idle to real quick WOT, but not as bad as yesterday. Don't have to baby it quite as slow initially on trigger pull. I'll see what Sunfish's advice does on backing off the L about a quarter turn here in just a little bit.

It may not need a full quarter, now. Maybe an eighth. Turning out the L screw will richen it up a bit and lower the idle. Might need to raise idle a little?

 

[USMC615]

It may not need a full quarter, now. Maybe an eighth. Turning out the L screw will richen it up a bit and lower the idle. Might need to raise idle a little?

Gotcha...I'll give it a try here shortly when I get back out to the shop. Thanks.

 

[USMC615]

It may not need a full quarter, now. Maybe an eighth. Turning out the L screw will richen it up a bit and lower the idle. Might need to raise idle a little?

Exactly as you said...thanks Don. I dialed the L back a quarter turn, seemed a touch too much. Idle came down, turned back clockwise half way, had to barely raise the idle -T. Runs a nice rpm increase all the way up the throttle range. I may have to play with it again as the sea foam add may dictate a slight change as it may burn more gummed up stuff, but all in all, highly satisfied. It'll make a great, lightweight limbing saw, looks brand new, I've got a small handful of hours piddling around with it...just makes the ol' adage 'for free, don't knock it' that much sweeter.

 

[USMC615]

Here's a couple of pics of the resurrected little Craftsman 40 cc 18". He'll do just fine as a limbing saw, not a whole lotta weight to him. Runs like a top now, hopefully stay that way, but not gonna tax it too much, lol.