Old Chainsaw help

[Bluebird]

I seem to remember some knowledgable chainsaw maggots so I figured I would throw this out there before heading somewhere else. I recently inherited this saw, http://www.acresinternet.com/cscc.ns...a?OpenDocument

I can get it to start, but it stalls when I let off the throttle. After looking around on the web it seems that I have to adjust the "high and Low" screws. My problem is I don't know which one is which? You can't see them in the picture on the link, but they are sitting in the black spot right behind the starter handle. I was thinking the left screw would be high and the right would be low. If that is right then I still can't seem to get them adjusted right.

Any ideas? Are there any other adjustements I can make?

Thanks!!

[wolfy]

the super XL was the (unfortunate) weapon of choice for USFS thinning crews for a lot of years. most guys are now near deaf in the left ear (bad mufflers) and have arthritic knuckles (aka- homelite "white knuckle") from no anti-vibe.

that said- if it will start and run (high end scream or low end burble?) and the air filter is intact, i'd try this:
if it's just dying when ya let off the throttle, try screwing in the idle adjusting screw- it's larger and brass, sticks out to one side- while looking down from the top (air filter cover off) until screw contacts the "plate" on the side of the carb. you probably just need to bring the idle up to keep it running.

to adjust the carb-IF you have to, GENTLY screw both the hi and low screws in until they stop, then turn back out about 7/8 to 1 full turn. as i recall that should get you pretty close. adjust further as needed, get some experienced cutter to help you from there. good luck with that beast.

[Meadow Skipper]

Wolfy's right but first adjust the High and Low screws the way he said, then adjust the idle adjusting screw so that the saw will idle when you let go of the throttle. The high and low screws adjust the richness of the fuel mixture at high and low throttle. IIRC, the high is on the left and the low is the one on the right. Right now it sounds like your main problem is the idle adjustment.

Here's how I adjust the High and Low screws. With the saw idling, turn the low adjust screw in (clockwise) until the idle starts to speed up. It's speeding up because the mixture is getting leaner. Now you'll back the screw out (counterclockwise) as you hit the throttle for short bursts. The spot you're looking for is where the saw first has a momentary hesitation before it starts to rev up. When the mixture is too lean, it will start to rev up the instant you hit the throttle. When you've made it rich enough to where it hesitates just briefly (like a nano-second) when you hit the throttle before it revs up, then the mixture for the low speed will be where you want it. The thinking is that it will be just rich enough to accelerate well under a load.

Now that the low is set, it gets exciting. You open the throttle to full and - with the saw screaming - adjust the high screw to the point where the saw runs at the highest RPM, then back the screw out (counterclockwise) about a quarter turn (it will slow down slightly as the fuel mixture gets richer)). This should allow a good fuel mix for the saw when it's running under a full load.

Incidentally, once you get the saw idling you should be able to tell for sure which is the high and low screw because the only low screw will affect the the idle.

And yes, I am near deaf. Fuckin' Homelites. Wear hearing protection and be sure not to cut the shit out of yourself when the saw is running at top speed during the adjusting. Two sets of hands may be an advantage.

[Bluebird]

Thanks, it definitely starts and runs. At WOT it really screams. I noticed that it was loud.

So just to confirm, turn the hi and low screws all the way in and then turn them both about 7/8 to 1 turn, adjust the idle screw so it will idle and then start playing with the hi/low settings to get it running perfect?

[Meadow Skipper]

So just to confirm, turn the hi and low screws all the way in and then turn them both about 7/8 to 1 turn, adjust the idle screw so it will idle and then start playing with the hi/low settings to get it running perfect?

You got it. Oh, and keep your chain sharp. Happy cutting.

[Bluebird]

I think I let the second rule about this saw slip through the cracks. I have been doing a bunch of cutting around the house and I think the chain needs a good sharpening. A while back I bought the little chainsaw sharpening attachement for my dremel. I understand the general idea, but there are some options I can't find the details on. Specifically, how do I determine the pitch of the chain? I don't have an owners manual or anything that came with the chain.

[Rideski]

I bought a hand file with a guide on it (which determines the pitch) for not too many $ from the local hardware store and it worked great. Make a huDge difference in the cutting ability.

[Meadow Skipper]

The chain may have the pitch engraved on the guide/drive link - the part of the link that fits into the groove on the bar. But essentially, pitch is the distance between three consecutive rivets, divided by two. IOW, measure from the center of a rivet to the center of the rivet after the next one, then divide by two.

http://www.oregonchain.com/faq.htm#chainpitch <- good faq page

Oh, and go slow - you can fuck up a chain in a hurry if you're using a power sharpener and don't know what you're doing.

[wolfy]

on a lot of saw bars the pitch/guage and number of drivers is given on the bar- usually stamped in on the end near the power head. websites such as Meadow Skipper mentioned or Baileys online can be a good source of info. your local saw shop could tell you if you ask the guy at the parts desk. good luck with it.

[bio-smear]

After you've run it for a while on your new mixture settings, pull the plug and look at the electrode area....it should be a nice dry mocha color. White or whitish = too lean, dark or black = too rich. The trick about adjusting the high speed screw to max rpm and backing off a little should get you close.