Anybody know anything about chainsaws

[TrogL]

I just bought a used chainsaw. It's a McCullogh MAC 140. The guy showed it to me and had it working. I brought it home and could't get it going for longer than a minute or so. It keeps stalling like it's running out of gas. The only thing I did to it was tighten the chain because it was in danger of falling off. It still turns easily.

Here's a picture of the controls.



The red button is the master on-off switch. The little spring on the bottom of the t-handle is the oil pump. The main throttle switch is under the handle out of sight. I have no idea what the big square button the right does. I suspect it's the primer. There are two black things to the left of the name plate. The far left one with the silver screw is the choke. The other one is actually three screws marked "idle", "lo" and "hi". The Idle screw is actually a button you press in to lock the throttle in the idle position so you can start it. I suspect the other two are carburator adjustments.

I've googled this and the only thing I've come up with is a suggestion to put all three screws down to their lowest setting and back them off 1 1/8 turns. I tried that and it wouldn't start at all. The idle screw was too low to engage. I had to back if almost all the way off. If I put the "lo" screw in about another half turn, it would start for a moment, then die. When it did run, it put out a lot of grey smoke. When it got warmed up, it wouldn't re-start at all, no matter what I did to the "lo" or "hi" screws.

When I had it running for a moment, I attempted to cut some wood and it almost immediately slowed down and died. I oiled the chain but that didn't help.

I also had a look at the spark plug. It appears relatively new, but covered in oil. I have no idea what the gap is supposed to be.

I suspect the chainsaw is fine, just needs some running in to get old gunk out of it and maybe a new chain.

Any suggestions?

[uppityperson]

1. Only suggestion I have is hold it firmly,

move it back and forth quickly while saying vrrrmmmmm vrmmmmm vrrrmmmmm. Do chainsaws get flooded, have carberator thingys? Take it to a chainsaw place. They are usually pretty cheap, or go back to the guy you got it from to double check what you're doing.

[BiggJawn]

2. Is the choke off?

[TrogL]

3. Choke is off

Shouldn't need choking again until a couple of hours of non-use, right?

[BikeWriter]

4. It may take you a while to find the right amount to choke it...

Some of those things are a little contrary and can flood the carb.

[BiggJawn]

26. No set time limit.

If it doesn't start (all other things in order) then it needs choke, but as soon as the engine has idled a bit and warmed, then you can turn off the choke. Check the air filter, too. It's a block of plastic foam that should be a LITTLE oily, and not clogged up with a paste of oily dirt or soaked with lube oil. Clean it in gasoline and LIGHTLY oil it with 30W when dry.

2-stroke engines are notorious for clogging up if they're just set aside without servicing for the winter. The guy who sold it to you either got lucky, or had developed some sort of kludge to keep it running that he neglected to let you in on. Perhaps he kept poking the primer bulb while he cut. I think that black button to the right of the handle may be the primer. When cold, give it 3 squeezes and choke the engine before starting.

It may be worth-while to take it to your local shop and tell them you bought it used, think it's "gummed up" and you can't get to run right.

[Mayberry Machiavelli]

5. Good for dismembering Evil Deads. Sorry it had to be done.

[AlCzervik]

6. I wish ted Nugent had a bigger chainsaw with more kick back.

oh well, theres always next time.

[Floogeldy]

7. Yes, I know.

You have to talk to them.

In fact, you have to yell at them. You have to use profanity at them.

Successful phrases are such like:

"C'mon, motherfucker!"

"You cocksucker!"

"Start, you son of a fucking bitch."

"Kiss my ass, you piece of shit, if you don't start!"

I'm sure this will help.

Let me know how it turns out.

B-)

[Redstone]

8. My Uncle Stumpy knows a lot about chainsaws; I'll ask him.

Redstone

[Floogeldy]

17. If your Uncle's name is "stumpy," he doesn't that much about chainsaws!

B-)

[Redstone]

28. Well, I didn't say he was GOOD with them, just that he knows

a lot about them. Hence "Stumpy."

Redstone

[TrogL]

9. It's not the chain

I figured out how to disengage the chain when you're trying to start it (pull forward on the big black handle at the front).

It won't even sit and idle reliably.

[Eureka]

11. Don't rev it like that

The big black handle is the safety clutch (if saw kicks back your top hand will push this forward and disengage the chain). It is possible to damage the works by revving too much with the clutch engaged (you may not too, but it is possible)

[Eureka]

10. Plug oily, mix too rich

Or so I reckon anyway :-)

If it doesn't idle very well, start it and keep it idling as best you can, then adjust the lo screw. Unfortunately, I can only tell you to adjust it until it sounds right, sorry about that. As far as the sound goes, you will find a 'bell curve' type of noise, where it will be a little off, keep twisting, sounds about right, keep twisting, it will rev a little higher but sound wrong.

Same deal for the top end, only you use the hi screw and instead of letting it idle hold it on full throttle.

As for gapping the plug without knowing the proper gap... pull the plug out, connect it to the lead and earth the plug thread (you can just rest it on the cooling fins for example) then turn it over a couple of times. If you're getting a clean blue spark that will probably be close enough.

Hard to start when warm may be tuning, but it's also a symptom of being a two stroke.

Apologies for the lack of specifics, I have the same trouble explaining to Mrs Eureka about hard to start engines, as 'it will sound like it needs fuel, or it will sound like it doesn't' just doesn't convey that much info, but I hope it helps to some degree.

[TrogL]

12. which way is "rich"?

in terms of having the screw in or out?

[Eureka]

13. I think richer is clockwise

but sadly, I'm at work at the moment, or I'd be straight down the shed to confirm :-)

I have a second hand McCullock that was 5 years old when I got it 5 years ago and it still rocks! (I gotta get a new one soon, but the old one is great for it's age)

[specimenfred1984]

14. Fuel and Fuel Filter

If it's a gas/oil mixture, the mix has to be correct. And, if the gas filter is dirty, only so much will get through. It could be a gas line too if it's leaking gas anywhere. Just keep tweaking the carb jets that you tried tweeking earlier while the saw is idling to get the best adjustment for that saw.

Check the air filter too. Also, try some "Stabile" or other gas additive to see if that helps.

Stihl and Husqvarna are better saws, try one of those next time.

[Eureka]

15. Good point

Once you mix two stroke oil with regular gas it has a short shelf life. If you (TrogL) didn't mix and put in the fuel, tip it out and start again. Old fuel can cause all sorts of problems.

[TrogL]

18. Where's the gas filter??

I looked at them but couldn't afford them and they were too big for what I wanted to do.

[Eureka]

19. If it's like the one I have

there will be a gas line running into the tank. It will have a cylinder on the end of it with a mesh filter over it. You might be able to loop it with a bit of wire and pull it out a bit, although there usually isn't much slack in it so it might not come out further than the filler hole.

[specimenfred1984]

20. You'll Have to Follow the Gas Tank

and see where it leads you. You'll probably have to take some cover(s) off.

Even if you can find a manual, it might be written or diagrammed poorly. You'll just have to get dirty and look inside the thing. I googled it too and found nothing.

Be careful when handling the chain, they are sharp!

[TrogL]

22. not this chain

I doubt it could cut butter. The saw says it's "self-sharpening".

Any hints on how to sharpen a chain? I've got a good stone.

[specimenfred1984]

24. That's Really Easy

All hardware-type stores sell round files for sharpening chains. You'll need to know what size/cut chain it is.

Then, you just run the file in one direction through each cutting blade. Replacement chains go for about $20 online if you look around.

Sooner or later you'll have to take the saw apart just to clean it up. It's a pain in the butt, saws are dirty, smelly and noxious. It's better than paying someone a fortune though. The shops around my house charge $100 minimum just to look at the things.

If you use the saw a lot, it'll get all clogged up with wood/oil gunk and you will have to clean it up just so it'll run well.

[wideopen]

16. I have 5 of them

and have for 15 years. To start out- my first suggestion would be to take the mculloch back and buy a stihl. If thats not an option do this- go get a new air filter, spark plug, and fuel filter and install them. dump out the fuel in it and refill w/proper mix using only echo/stihl 2 cycle oil. Turn both screws out 1 turn and see what it does.

[TrogL]

21. I'm stuck with it

No refund. Got it for almost nothing at a pawn shop otherwise I would have bought new.

I like it because it's really, really tiny. Next week I'm probably bringing down a diseased pine tree in a very small area and I don't want to be lugging some monster up the thing.

[wideopen]

23. Well, then let's make it run

2 cycle engines are very simple. Do the maintainence first, close the choke and it should try to start. Open the choke and fire it up. If it doesn't pull the spark plug- is it wet? if so it's got gas. If not dump about a 1/2 teaspoon in the spark plug hole, put the plug in and start it up, choke open. If it's wet hold the trigger wide open and start it up. 90% of the time one of these plans will work.

[HamstersFromHell]

25. If the air filter is clogged you'll get the wet plug all the time.

Drain the gas tank and if the air cleaner is foam (most are) clean it in gasoline (not with oil mix) and squeeze out the excess, hang it up overnight to dry throughly. The next day apply a few drops of motor oil to it, then squeeze it up and roll it to distribute the oil. Refill the gas with the proper mix of gas and a good 2-stroke oil. Replace the spark plug. (Consult the plug charts for the right plug...people can be way sloppy when it comes to replacing with the correct parts sometimes.)

The three screws should be idle (idle speed), low (idle mixture) and hi (high speed mixture). Turn both the lo and hi screws in till they seat lightly. Do not force them, you'll damage the needles and possibly trash their seats, which means new carb.

Most (disclaimer, not all) mixture screws should be in the range if 1 1/2 to 2 1/2 turns out under notmal operating conditions.

If you can get it started long enough to get it to operating temp, then you can adjust the mixture screws...if it's been run less than 5 minutes, it's not warmed enough for correct adjustment.

Once you get it running, set the idle speed screw so it idles without you having to use the throttle. Once warmed, slowly adjust the lo screw to obtain the highest idle speed. Readjust the idle speed screw as necessary to get as low of an idle as you can hold smoothly.

Once you have the idle mix and speed correct, give it full throttle briefly and back to idle...it may hesitate, if so, turn the lo screw out 1/8 - 1/4 turn and readjust idle speed. Do this until the saw revs easily when you give it throttle. If it stalls when you release the throttle, add a little idle speed to prevent stalling.

Now that you're this far, with the chain break off (clutch and chain working when you rev it), give it full throttle and hold it....adjust the hi screw to give the highest speed, remembering that on 90% of those screws, clockwise leans the mixture, counterclockwise richens. You want to back it out (counterclockwise) until the point it slows and starts to "blurble", then ease in back in just a tad. Now you're in the ballpark for the hi screw. (It's still too lean to cut efficiently and may cause damage to the engine if operated in this manner.)

Next, back the hi screw out about 1/2 turn from where you just set it and try to cut a something that provides a decent load to the engine. You want it to be able to try to rev as high as it did with no load with it fully loaded. Touch up the hi screw in 1/8 turn increments till you find this spot. Find the spot that it blurbles at while fully loaded and working hard and turn in (toward lean) 1/8 turn. This should have you set for maximum efficiency w/o risking burning up the engine. (Chainsaw carbs are extremely simple, and do not compensate for load...why you have to set the hi screw to run a bit rich with no load so it get's the proper amount of fuel when fully loaded.)

If you can't get it to run right with the 1 1/2 - 2 1/2 turn range, I'd suspect you need to rebuild the carb.

Hope this helps!

[LynneSin]

27. Everything I know I learned from "The Texas Chainsaw Massacre"

:shrug: