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McCulloch Pro Mac 610 Problem
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Paul    Posted 10-24-2003 at 06:00:51       [Reply]  [Send Email]
Hi Guys

I recently picked up a few chainsaws at a local auction two of which a McCulloch saws.

I am having a bit of a problem with the old Pro Mac 610. When I first got it home I could get the thing to run any more than a few seconds so I pulled off the air filter and noticed that the fuel line was all hard and brital and in one spot was leaking fuel everywere so I replaced it and sure enough it start on the the third pull.

It seems to run like a charm, idols perfectly in fact it idols somther than any of my other saws!!
My problem is as soon as I try and cut a piece of timber it just dies. At first I thought it might have been a clutch problem but it does not sound like it is slipping.
It sounds like the thing labours when it is under load like someone is grabbing hold of the chain (not that you would of coarse :o)

I don't have a guage to check the compression on it but it doesn't feel to bad when you try and start it.

I pulled the muffler off to check inside the port for any piston scoring but it looks quite good.

If it needed a new piston ring in it would this be a sympton that would show that

Could any Pro Mac users shed any light??



Jay    Posted 03-23-2008 at 16:58:02       [Reply]  [Send Email]
Just got my 610 running good again.
I had simaliar issues with bogging.
There is a fuel filter in the tank that you can snip the line and replace it with a filter from your local chainsaw shop. I also pulled off tne carb. and cleaned the small screen and entire carb. with carb. cleaner. (pressure can) Also clean your air filter with carb cleaner.

Paul    Posted 10-26-2003 at 22:06:36       [Reply]  [Send Email]
Thanks for the replies guys!!
OK I have made a few adjustments to the Mixture screws and although that helped a little it still seems to be bogging down alot.

I took off the muffler and gave that a good clean out but it really wasn't all that bad I thought.

I also took the Carb off and opened it up, I didnt strip the whole thing down but I opened up either side of it and actually found it had a few remnants of the old Fuel Line so I cleaned all that out.
Stuck it all back together and once again it seemed a little bit better but still does not seem to run all that hard when cutting.

The Chain could probably do with a sharpen but it's not all that bad, I have got a little 48cc homelite that seems to go harder than the Pro Mac so there must be something I am missing.

There is one thing that I did not do when I cleaned out the carby, there was a small brass wire filter with a Steal ring holding it in place on the diaphragm side which I couldn't seem to get off. I was a little hesitant to put pressure on the thing in case I lost/broke it but one would assume if it was dirty it would have been on the outer side of it not inside correct??

One thing I did not mention in my first post is that once you first get it started if you try and hit the throttle it will bog down real bad and if you give it to much it will just stall. If you wait a minute or so till it warms up it is ok after that.

I am really not sure what to do next, any idea's would be a great help!!

Thanks again,


Woody    Posted 12-05-2003 at 23:27:17       [Reply]  [Send Email]
Quit being cheap and take it to a repair shop and have it looked at. Bet it needs the carb rebuilt or something simple.

Harley    Posted 10-25-2003 at 12:42:32       [Reply]  [Send Email]
Just got done pulling mine apart. (post JD 55ev dead) If your cheep like me you can make your own psi. gauge out of an old spark plug welded to a short peace of black pipe. put a 90 on it and a gauge. the only problem is the gauge will not hold the top reading, but if your quick you can get an idea of what it is running.

Danoe    Posted 05-02-2004 at 08:45:25       [Reply]  [Send Email]
I don't know if you tried or thought of this or not, but 2-cycle engines are VERY TOUCHY about exhaust flow. As you probably know, the entire fuel induction system is dependent on a freely-flowing exhaust system, and while the mufflers on 2-cycle engines ARE somewhat small, there IS A SPARK ARRESTOR SCREEN (usually made of stainless steel) that is located inside the muffler itself and the entire exhaust flow MUST pass through it. The muffler has to be dis-assembled to get to it, but once removed, a propane torch can be used to heat it up CAREFULLY, until it glows RED, let it
cool down and WORK the screen with your fingers in a SEE-SAW motion to free any carbon particles that might still belodged in the wires of the screen.
Typically what happens is that if some other oil, other than a 2-cycle lubricant (ashless) is used, for the fuel/oil mixture, it will carbon up this screen more quickly than it should before the exhaust temperature gets hot enough TO CLEAN ITSELF and FOUL THE SPARK ARRESTOR SCREEN. While a 2-cycle engine will "sometimes" idle in the early stages of this condition, when you put the juice to it to cut, the exhaust flow increases substantially and the combustion chamber is polluted with spent gases (NO OXYGEN), further exacerbating the COKING problem, and preventing the engine from producing full horsepower, as it should. That is why these are called 2-cycles engines - either they run or they don't. :O)

Danoe    Posted 05-02-2004 at 09:03:33       [Reply]  [Send Email]
I almost forgot....a quick check to see if this is the problem would be to fire up the saw without the muffler on. if it runs fine, then you have the solution. As previously mentioned, the muffler is designed to be there as part of the induction/exhaust system, so it will run more choppy at an idle. :O)

Paul    Posted 10-24-2003 at 16:51:05       [Reply]  [Send Email]
Hi Guys

Thanks for the replies!!

The Chain could do with a sharpen but it should
certainly cut through the small piece of timber
I was testing it on.

I was thinking of pulling down the carb today and giving it a clean out, I was a little concerned about gaskets though as these old macs are a little hard to get parts for now..

Will let you know how I go.



Brian-2N    Posted 10-24-2003 at 09:36:59       [Reply]  [Send Email]
It idles smooth but how does it run at full speed? Cut wood at full speed and nothing less.
Does it hesitate when you throttle up? If it does it sounds like a fuel (carb) problem.
If it runs great not under load at full speed than I would suspect a dull chain. Don't force the saw through the wood. The saw should literally pull itself through the wood with a sharp chain. If you have to force the saw through the wood, thus making it die, it's time to sharpen the chain.

Dave Wi.    Posted 10-24-2003 at 07:29:56       [Reply]  [No Email]
Just a thought,if it idles smooth and bogs at the throttle,you could have a pluged or jamed high speed jet.

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