OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Chainsaws and Concrete Cutters McCulloch Chainsaws Mac Super 250

My mates Super 250 just won't start..... it's only 48 years old and done heaps of work..................
I put some fuel into the carb and it started......, did it a couple of times....
Been googling US forums and one said just keep priming and after 10 starts it might pull the fuel through...
Anyway I took the Tillotson HL63 carb off and want to clean it....
A kit cost $56......my father in law reckons the thing is not worth $56..... so I want to tread lightly and clean the carb, maybe it will work again with some carb cleaner and air.................................... try to keep the old gaskets...

He's going to give me a ride on mower that doesn't go either..........
fun goes on , when time permits

speedy

I'd get a kit - you couldn't get an equivalent saw for $56 .... Great saw - just check piston and bore before spending. $$$$

hi Dieselboy
I took the carb off and tried to lever the sections open with a blade and squirted in carb cleaner..... tried to take it apart without destroying gaskets..
Just to get it going. It kicked over, even used engine start spray.....
There's spark, and heaps of compression. It's a workout to pull it over a few times.......
I will check the points, as it has contact breaker points....
See if plug is wet......
cheers
speedy

Soak it in acetone overnight......Have you checked piston, rings and bore.....? Good luck - I'm a sucker for old chain saws

Parts are nearly impossible to get for these old saws if is the McCulloch as they have been out business a good number years now. If it has good compression and fires on a fuel mix prime then the carburetor is likely the root cause.

With this being 48yrs old I would not expect the gaskets will loosen without tearing. And getting a kit is best if available and you are willing to buy one as they are expensive now due they are becoming rare, plus you have to pay a premium because of the currency exchange rates.

I checked the air flywheel gap , set it to 17 , slight spark, points area dirty........
My ozito water blaster does the job at $ 87.
Just checking it all over...... is so dirty after 48 years....

speedy

Watch the points and capacitor completely dry - any moisture will rob you of spark

I have to reface points and set. and maybe check condenser....
But I guess to turn motor over you go on other side clutch area....
My mate is not in hurry and I have a lott \\ on ..... but it's relaxing just settling into a problem........
i sold his mums old rover for $50 so I owe him some time......................
cheers
speedy

Refaced the points gap 20 th inch, set gap flywheel 17 th inch .... I soldered a loose wire ends coil to points.....
now I have no spark........
I'll check a connection to coil.
It's electrical......................
Just got to check a solder job.
speedy.........

G'day speedy,
Here's an IPL download for the Super 250, which may be of some help; http://www.smallenginediscount.com/Super_250_May_70.pdf

If you're not getting a good spark at 0.017" flywheel air gap, try 0.010" - that seems to be a common spec for Macs of that vintage.

Thanks Gadge. I set the flywheel gap and it got a good clean and checkup. I must have a short , where the wires attach to points post. There's a fibre sheet.... I'll check
speedy

I have got spark. Just couldn't see it in the light........ Not a big spark. It didn't kick over even with starter fluid, then my arm wore out..........
Try again soon.

I put a kit in the tillitson carb, and a new fuel line. It didn't kick over, I want to check the reed valve.....
But how do you get to it? It's under where I took the carb out, removed 2 bolts, and the handle bolt...
there's the oiler rod...

speedy

G'day speedy,

Yep, that airbox does have to come right off, as the reed plate is sandwiched between it and the barrel.

By the look of that IPL I've linked above, there will be two external slotted screws that go through lugs at the front of the airbox. As well as the two internal hex bolts, and the handle screw. Look at Fig 4 as well as Fig 1 to get the idea.

I would have to take oil and fuel tanks off...... new gaskets etc. I shone a light through the inlet and could see the reed valves. They looked ok, seating and not bent. I put my thumb over intake and could feel them pulse when I pulled the starter, so I will take them as OK.

But a weak spark, found a washer on the flywheel magnet??? Anyway took the flywheel and will recheck points and wires. Someone suggested pinched wires.... maybe a new condensor..
Here's a tip I read maybe here about how to hold a flywheel to take the top nut off. Just thought I bring it up for ones who didn't know the easy way to hold a piston in place with telecom rope or light rope.

Nice rain in Bundy lately, missed the tennis ball size hail and the two tornados..............
cheers
speedy

I wish I had your patience. Working on this would drive me crazy, even though I love real chainsaws like this.

There is a weak spark, I want to try a new condensor.
Just wondering if a Victa one would do the job? Maybe I should just try it.
speedy

Well Speedy if you happen to have a Powertorque module why not try that, then you don't need the coil or the points, nothing to loose.

I seen where you say it had heaps of compression but did actually measured it?

Here I use 100 psi as a measure of minimum compression for a starting 2 cycle engine. Below that I seldom get one to start. It can be just stuck ring(s). I also had a couple Stihl 2 two cycles lately that had plenty of compression according to my gauge but losing it just the top of the compression stroke due upper cylinder damage.

Hi Norm,
I have a module from a 160 full crank, I think. Anyway I connected it up, you need to keep coil, but points and condenser went.
Not a big spark, but I could feel a bit of voltage in my fingers....
Maybe a better coil and module would do the trick.

Hi AVB I'll try to get a compression gauge and test.....
cheers
speedy
Bundy

Speedy, you said you had a weak spark with the points, is it any better with the module fitted? You need to be able to see the spark through the spark plug held against the head to get an idea if the spark is good enough

The spark is weaker with module, but still just see it with points.
I want a big blue spark like many B & S engines I have worked on. I have a few BS coils. Might try to put one on....
I'll measure the holes on the Mac coil.
cheers
speedy

Don't attempt it speedy it won't work, you can't get the timing correct, don't ask me how I know. It sounds like your coil is the problem and that will probably be the end of the chain saw. I have a Solo chain saw here with a dead coil, just haven't got around to taking it to the scrap and it is in good condition apart from the coil. I also has an Echo blower with a dead coil that I tried to fix for a friend, just on $100 for a coil so it to went too the scrap.

If you are using resistor plugs that spark will appear weaker. If using a resistor plug try a non resistor type.

Also the color will not always be bright blue. If you live near the sea coast it can even be orange due to sodium in the air. Here the sparks are usually white.

Thanks AVB, when I use a non resister plug, people around the neighbourhood have problems with their TVs ............
The guys down the road have an old motorbike and when I hear it start the TV goes haywire......
It did fire for a blast once..... that's why I keep going.
Is there a way to test the coil? My mate will but another coil as he wants to get this old thing setup as a log slab cutter. He will make a steel frame up and make slabs. They use them for fencing... and other things.

thanks
speedy

Speedy which coil do you have? Or would you rather have the 1963 service manual and the 1965 supplement?

It's a 1970 model saw, with a yellowcoil. I will get the number.
speedy

See if this helps then.

AVB, It has E67 stamped on coil,so it's top row.
Just bought a cheap multimeter, so now I will do some measurements.............. bit of a learning curve/hurdle.
speedy

OK AVB I did some testing and familiarising with multimeter.
Got reading of .02 on primary , should be .025 to .5, but then it was all over the shop... changing........
But the secondary was more stable at 5.89, should be 3.5 to 5.00

I will look around for another coil...... they are laying around sheds etc , just a matter of finding one.....
speedy

I heated up the coil in case there was moisture in it, closed the air gap flywheel, bodgee rigged a Victa condensor.
Bingo, a big blue spark.
I heard there was only one Macullock condensor so if I can't get one, I'll just use a Victa one.....
Feels better
speedy

It should be .18 - .22 uF capacitor.

Cross referencing here of the Mac 50074 (superseded to M85358) is coming up with a Kohler pn 230722S

OK, I got the Kohler condensor, and fitted it, great spark, bit white not blue, but that was OK.
I assembled it and pulled away a bit, it fired a couple of times, but dry plug so no fuel.
I pulled carb apart and put correct gaskets in in right order, but with sore arm, I mounted the saw in my vice and used electric drill to turn it over...... it fired once.....
But a wet plug......... even used starter spray.......................
One of my new year resolutions is to get this Super Mac out of my workshop..............!!!

Yesterday a bee was inspecting all the holes in it looking for a new home.........a big gray bee. Wouldn't leave me alone....
Maybe it was the colour yellow..... want to hear something funny.
I was at the pool with a ladyfriend once and she had a t shirt on with a big sunflower pic on it,,,, and a bee landed on the flower......
speedy

Speedy I worked with a bloke with a big mop of red hair, he was always being chased by European wasps, bees never worried him it was always the wasps. He would start swinging his arms around and I knew he wasn't having a fit, wasps were after him. I did tell him to dye his hair black.

I put 4 Orings on machine today, 2 in carb and 2 for fuel and oil caps....
Didn't fire, pulled the spark out, one flash then nothing.
I need a coil.........
There must be some laying around.........
I'll check US forums
Even out Mac dealer... he didn't have anything come up for that model, but I will try another dealer..
speedy

Speedy you don't give up easily, can't say I have that determination

The spark was bad, I replaced the two wires and clips on the coil and now I have BIG spark...
It starts and runs with carby starter...... so points and coil are good now....
I put a kit in the Tillotson HL 63G carby, but I must have missed something.
I see on youtube some excellant videos on installing the kit and learning about this fantastic carb... so many models....
Even new Chinese copies for $16 or $20...... so prospects are looking up.
work to do
speedy