Chainsaw help

[zwiller]

Was gifted a 10YO-ish McCullough chainsaw (MS42) that hasn't been started in years. Managed to start it with the help of some fresh gas and while it smoked a good while it eventually ran half decent and clean. After a cut or 2 it became readily apparent that the chain needs sharpened. In the meantime I also noticed it tended to bog down when throttling. Not a stick burner (yet!), don’t fell trees or cut firewood often but the family is very fond of the firepit and I find plenty of wood free for the picking so I’d like to have a working chainsaw around.

First question is: best to replace chain or sharpen? From what I can tell it has never been sharpened before and looks like I have plenty of meat left. I can put a wicked dangerous edge on chisels and planes but I feel sawblades, jointer knives etc are best left to professionals. The rat tail style hand filing looks doable for my purposes/occasional use. Might be a good idea to have a spare chain though…

Second question is relating to it bogging down. Now I need to check air filter and give the carb a quick cleaning and maybe a plug but from what I researched I may need to adjust the “H” screw. Headed in the right direction? I've seen alot of wood discussion around here and figure I could get some good advice. Any other advice or suggestions appreciated. Thanks in advance.

 

[zippy12]

There is a part number on the carb. Run that number on Amazon and you might be surprised how cheap the entire carb is....Yes set the "L" until the saw idles right then adjust the "H" to get the full throttle working right...

I use a dremmel chain sharpener to touch up my saw chains... Also make sure the chain oiling is working right.

 

[browneyesvictim]

I have the same old saw.
A hand file is an easy thing to put a quick sharpen on a saw. Its a muscle memory learned thing like using a wet stone when sharpening a pocket knife. I almost never swap chains. Learn the correct angle and slope and have at it! You sharpen with the chain on the bar anyway. It should take you less than 5 or 10 minutes. The biggest thing is learn to keep the tip of your saw out of the dirt to prevent it from getting dull in the first place. One other thing is to note the SIZE of the saw file you need to match. Find an old timer or logger that will show you how to do it.

Before you go messing with your carb adjustment... You should have a place on your saw for bar oil to lubricate your chain. have you filled that? Any old used motor oil will do. You don't have to buy special bar oil.
Check for the correct tension on your chain. you should have an adjuster on the side of your saw.
There is a safety bar in front of the handle that is a bar brake. Make sure it is functional when it is tripped. Perhaps it is tripped and bogging you down?

 

[browneyesvictim]

Straight vinegar on any aluminum will clean it. Better yet if you can boil it. But you will not be able to clean out the teeny-tiny orifices in the jets without taking it apart. I see you are in Ohio, and right in the middle of corn country.. but, let me tell you... Ethanol is the worst thing ever to have happened to carburetors like that! I promise you will open the carb and find it full of white sludge/powder (aluminum corrosion) if it has sat for a year or more. That is unless fuel treatment was used, or non-ethanol gas.

 

[zwiller]

WOW. Thanks guys!

I am pretty handy but never had luck with carbs. I would just replace it rather than rebuild. Willing to try and break it down and do a good cleaning first tho. Pine Sol is new to me. I do keep some carb spray around. A good squirt good enough or long soak/boil better? Hope the carb can be adjusted without some kinda special spline tool.

Dremel tool sounds cool but I am pretty handy with a file and already familiar with the pitch/angle and that they alternate on the chain. Use a drill bit to find the size I need?

Yes, ethanol. What's best protocol? But high octane gas/use stabil/or? I read you can buy premade high octane stabilized stuff now too. So, the common issue is aluminum corrosion plugging up the orifices/jets? (I have a leaf blower is similar condition)

 

[browneyesvictim]

I just had to clean 3 cabs this week on 4-wheelers that had sat through the winter with regular (ethanol blend) gas. The jets were completely corroded closed and had to be replaced. Out here, it is common for gas stations to carry non-ethanol premium or a blend for ATV's, power tools, lawn equipment etc. That is what most insist on for trouble free problems out here on the coast- especialy the ATV's on the dunes etc. It doesn't have to be high octane- Just no ethanol. Or you can add the fuel additive, yes that is supposed to be just as effective.

Yes on the drill bit size to gauge method!

Good luck on finding a new carb for your Mac- They are discontinued and new parts are not available. I wish I could find some piston rings for mine.

 

[SmokinAl]

I use a file on my chain saw chain, everytime I use it, just a couple of passes on each tooth & it cuts great.
Never had any probs with the carb, but I did have the oiler quit working.
Al

 

[zwiller]

Forgot to say but yes put some motor oil I had in there for the bar. Appears to be working well. Need to check on the brake, there is some play in the handle and missing screw or bolt etc and not sure if a factor. Not even sure how the brake even works. Tried to find a manual but struck out.

I think I can get medium grade no ethanol around here. I use stabil for storage but never used it with 2 cycle stuff. That is gonna change.

 

[browneyesvictim]

Sounds like a good plan. As for the brake. Push it forward hard and it will pop forward and engage the brake. Pull it toward you and it will disengage the brake. When the brake is on it should lock up the chain from moving. It is there to protect you if the saw buck back at you. As the saw raises, your forearm is supposed to trip that bar and stop the chain.

Holly2015 - I will try the PineSol. Not afraid to try something new!

 

[DIYerDave]

Buy and install a carb rebuilding kit. Replace old fuel lines with new. Mix up the correct fuel/oil ratio. Then go online and look up the "correct" way to adjust the "L" and "H" needle valves. And be careful not to switch those two needle valves. They are not the same.

 

[HalfSmoked]

Most gas mixing oil for 2 cycle already has stabilizer in them.

Warren

 

[johnmeyer]

I don't know much about chainsaws, but I've cleaned, re-built, adjusted, and replaced a lot of 2-cycle carbs (blowers, trimmers, etc.). The price of new carbs is so cheap (my last one was $11.50, shipped), that I can't imagine ever rebuilding again. (If you click on that link, you'll see it is for a cheap Ryobi engine; if it were a carb on one of my Stihl products, it would not be so cheap, and I might instead still get a rebuild kit).

BTW, the ultimate authority on chainsaws is Bearcarver. His online name comes from the fact that he used to carve full-sized bears using various chainsaws. While he isn't doing it anymore because of his health, I'm sure he has answers to pretty much any chainsaw question anyone could ever ask.

 

[zwiller]

THANKS AGAIN.

Sounds like a good plan. As for the brake. Push it forward hard and it will pop forward and engage the brake. Pull it toward you and it will disengage the brake. When the brake is on it should lock up the chain from moving. It is there to protect you if the saw buck back at you. As the saw raises, your forearm is supposed to trip that bar and stop the chain.

Brake works. For a minute I didn't think it even had a brake...

Got the dremel bit set as it was cheaper and I am pretty good handling it. Chain is SHARP now. Sharp enough I need to find a cover or something to store it. Tried firing her up. No dice. Noticed the primer is sticking. Long story typed with gasoline smelling hands short: I think the carb is clean and the lines are messed up. Line in tank running to carb is really short (barely past hole from top) and I do not see a filter. Ethanol ate it maybe or melted? Somewhat makes sense as it acted ran better slightly vertical than horizontal. Am I correct the fuel line should be long enough to hit the bottom of the tank and fuel filter should be there? Best I can tell is the tank is like a keg of beer in that pushing the primer in sends air pressure to top of tank and forces fuel up from bottom into carb. No way that can happen with the line that short. Kinda funny now that I've looked the saw over well, the adjustments for the carb can easily be made through some holes in the cover...

Bearcarver Maybe he wants to play along but if he is like my Dad he'll just tell me to throw it away and a get a Stihl. ;)

 

[chopsaw]

Does it bog down under load , or no load ? Also , there is a depth stop on the chain that has to be set correctly below the chisel tooth . Some of the old Mac's had clutch issues . Hangs and drags that results in poor idle and what seems like lost power .

 

[zwiller]

Didn't matter bogged down no matter what. Got worse as I continued. If anything I think the position of the saw helped. Thinking back, kinda made sense that bogging down was loss of fuel. Fired right back up but I think the saw was angled down a bit so fuel made it to the line. Makes too much sense tho... :rolleyes:

Only saw depth stop talk 1 time when I was looking up sharpening. I see now it controls depth of cut and needs to be filed down. I'll pick a gauge up when going for fuel line.

 

[mike243]

The bulb acts as a siphon to prime carb,if soft it will have a hard time springing back to draw gas

 

[HalfSmoked]

zwiller thanks for the like it is appreciated.

Warren

 

[kawboy]

My ice auger acted like that once, I cleaned the carb multiple times. Don't remember how I stumbled on it, but pulled my in tank filter out and it was almost completely plugged. Cleaned it up, and ran fine. I still have to clean up the carb every fall, but that's the nature of the beast with todays fuels. I agree with going with non-oxy fuel. That's all I run in my bikes, boat, chainsaw, auger, mower, wheelers, etc......

 

[ghostguy6]

Lots of good advice on the thread already. Replace all the rubber hoses. They are cheap and it easily rules out any small cracks letting air in. I would also suggest running some Seafoam Motor Treatment through the engine. Take your fuel line off and manually flush some straight Seafoam into the carb with a syringe and and let it sit overnight. Reconnect your fuel line and run a tank of fresh, no ethanol mixed gas (gasoline, 2 stroke oil and Seafoam mixed according to can directions) through the saw. The saw may be hard to start and will run very smokey for the first few minutes so do this outside the garage. While Im usually not one to push for any specialty engine products this stuff really works well. Its like Franks Red Hot, I put that **** on everything.

 

[johnmeyer]

I agree with the recommendation to replace the bulb.

Also, check to make sure the head bolts are tight. I've had two different engines where the bolts got slightly loose causing air to get sucked in. The engine would start, but as it got hot, it would lean out and lose power.