McCulloch Super 250

[Brmorgan]

A few weeks ago I drove up to visit fellow member "jockeydeuce" (Rob) and did a bit of trading, and came home with this seized but otherwise pretty good looking Super 250:

It's complete and in overall really good condition from the outside. Nothing broken, just missing a few assembly bolts here and there, some due to stripped threads, and there are no spikes. I think I could use the ones on one of my other big Mac projects for a template to cut a set though. There's a fair bit of pitting on the lower rear handle section, and a bit on the underside of the case as well. Not terrible though.

I'd never taken apart any of the old big Macs yet, just my 10-10 and more recently the PM605. Let the fun begin!

Better than I expected under there! The cylinder and flywheel are both fairly clean, all things considered.

Pretty clean in the carb box too. So that's where the spike mounting bolts are! Hopefully this big old Flatback isn't a writeoff. I've never worked on them before.

Well, THAT'S never a good thing! This oughta be interesting...

 

[Brmorgan]

Yep, the water's been here too... Strangely enough, the fuel lines are all in really good condition, not soft and mushy or brittle at all. What are the best substances to use to dissolve all those old deposits? I'm thinking of hitting it with the HCl acid really quick, or vinegar perhaps. NaOH and Varsol didn't do much to it.

Everything looks really good under the intake block too. I was encouraged at this point because the both sides of the piston looked good through the ports - but I could see some water corrosion in the combustion chamber through the plug hole.

Time for the grease-gun trick to get the piston unstuck! It was seized in a spot where the rod wouldn't let me pull the crank out of the topend. It took a while but it did do the trick. The piston and cylinder are both perfectly usable, but the rings were stuck. I busted one getting it out, but I can't even budge the other one yet. It's going to have to soak for a while. Any leads on where I can get rings for one of these (without paying a fortune)?

The cylinder cleaned up really well actually. No marks anywhere.

Here's everything laid out after being cleaned:

So far all I think it needs are new rings and new gaskets all around, an air filter, rubber for the rear handle, and probably a carb rebuild. There's no mesh or screen around the starter/flywheel either, is there supposed to be? I'd be interested in a source for the above parts, if possible. I don't mind stenciling and cutting new gaskets if I have to, but if new ones aren't a total ripoff I'd rather just go that way.

So, is there anything I should know about these while I have it all apart? They seem to have a really good reputation.

 

[parrisw]

Looks good. I got a Mac 250 sitting here forever, maybe I'll get to it someday!!

 

[Justsaws]

Super 250s are great saws.

I have no sources for parts and cut my own gaskets.

 

[Hddnis]

Good work on the Super 250.

There is one sitting at the scrap yard that looks like it might be a decent project, I go back and forth about making an offer on it.



Mr. HE

 

[ric5141]

Looks like a nice project. I love the old Macs.

 

[gmax]

There is supposed to be black plastic mesh around the starter/flywheel as you can see in the pic below. The site sponsor "Chainsawr.com" has some 250 parts listed http://store.chainsawr.com/search?page=1&q=mcculloch+250

 

[Saw Dr.]

What's a Super 250?

 

[heimannm]

Rings should be PN 55123, same as used in many of the 80 and 87cc saws and pretty readily available on e-Bay, Bob Johnson likely has them, probably Fayetteville Equipment Repair as well. Should be $10-$15 I expect. Check Bob or Fayetteville for other gaskets as well. PM me if you need an IPL to help identify part numbers.

Get a kit for the McCulloch carburetor from Joe Salva at Sugar Creek Supply ([email protected]), best prices for a good repro set of diaphragms and gaskets. Needle is the same as the SDC if it has problems.

The original "sawdust screen" would have been perforated metal, plastic versions are available as Gmax shows in his photo, same parts used on the SP105/125.

Have fun, I have a couple of Super 250's that I've only run in the shop, never had a chance to put a bar & chain on them and put them into the wood yet.

Mark

 

[pioneerguy600]

Interesting project Brad, too bad it had water inside it, that stuff does a lot of damage to old chainsaws. What makes the Super a ,"Super" in the 250 Mac. I have a near new 250 in the Canadian style and its an 80 cc engine with a 2.125 bore and a 1.375 stroke. Many of the Supers I have seen are the same bore and stroke but have heard they had a third port or sometimes called a boost port on the Supers. Does that extra port make them a Super?
Pioneerguy600

 

[heimannm]

From what I can gather, the Super 250's had more aggressive porting than the standard 250's.

Virtually all of the McCulloch's of the era (from the D-44 through the SP 125's) had the "third boost port" and though I've had many saws apart and back together again I am not sure I could tell you exactly what makes the third port special.

At least some of the Super 250's were 87 cc's with a 1.500" stroke, same bore (2.125") as the other 80 and 87cc saws of the day. I haven't bothered to check the stroke on either of mine to confirm which they are but I suspect there were more of the 87cc variety Super 250's if there even were two different displacements. With the old McCulloch's you could never be quite sure what you may find.

Mark

 

[Urbicide]

Interesting project Brad, too bad it had water inside it, that stuff does a lot of damage to old chainsaws. What makes the Super a ,"Super" in the 250 Mac. I have a near new 250 in the Canadian style and its an 80 cc engine with a 2.125 bore and a 1.375 stroke. Many of the Supers I have seen are the same bore and stroke but have heard they had a third port or sometimes called a boost port on the Supers. Does that extra port make them a Super?
Pioneerguy600

It might be all of the extra "ports" in the air filter cover.


I had "won" a set of 55123 rings from Fayetteville Equipment a little over a month or 2 ago on flea bay. The box looked pretty beat up in the auction picture. When the rings arrived, I had found that someone had put a set of of used rings in the envelopes in what was left of the original Mac box. They were nice & shiny, looked like they had been chrome plated. Tried to get another set from Bill. He said he didn't have any more & he refunded my money once I sent the rings back to him. I would be curious if he happened to find another set now.

If you can't find 55123 rings, you might check into a set of 55124 rings. Those are .010 over sized. You might have to file the ends down, but that is easier than going the opposite way.

 

[pioneerguy600]

The most I have done to mine was put a new fuel line in it as the line had gone soft and gummy in the tank. Never had to touch the engine, carb or even the sparkplug so I have not seen the insides of the engine itself. Got a bunch of them old yeller Macs laying around out in the outbuildings, must pull one apart someday.
Pioneerguy600

 

[jockeydeuce]

Sweet!! I'm glad you're tearing into the project, Brad!!!

That sucks about the water.....If it wasn't for that, it would have been a relatively easy project.....I know you'll get it though!! I'll be awaiting the video of that thing slingin' chips!!

Turns out I need the 044 parts, so that was a good trade....Thanks!!!

 

[Saw Dr.]

The 80cc Supers had the third port. The ones I have seen came with a yellow topcover. I have a few of the black topcover ones, and they're all 87cc's. There seem to be alot more of the 87cc ones.

 

[gink595]

Cool build! I was just working on one yesterday. How does the fuel line attach at the fuel tank, is there just a nipple at that end to slid over? I really can't see in there to tell?

 

[belgian]

Cool build! I was just working on one yesterday. How does the fuel line attach at the fuel tank, is there just a nipple at that end to slid over? I really can't see in there to tell?

Yes, there should be a nipple, as suggested.

 

[leeha]

Sweet project.
Good luck with it.

Post a video when done.


Lee

 

[Bret4207]

I have a standard 250. She's a torky old beast. Heck of a nice saw for the time.

 

[willysmn]

Mac 250

The third port: Is it in addition to the 3 intake ports on the front and 3 more on the back of the cylinder? Or are the 3 in the back the 3rd port?

In the old GO Kart days, there were the 6 ports described above and 3 finger ports up the side of the cylinder.