MAC Question

[coveredinsap]

For you Mac guys.....what's the trick to getting the spark plug cover off of the 250/super 250 model saws?

Thanks

(Oh, and also....where's the serial number located?)

 

[Lawn Masters]

Serial number is on the bottom of the crankcase, right along with model number. the trick to getting the plug cover off is to get a small screwdriver, slip it under the cover, and pry up gently, the cover will pop up, and you can turn it to the side while you do whatever.

 

[coveredinsap]

Thank you kindly. I thought that was it, as it appears a little chewed around the edges....but it seemed to offer more resistance and I was afraid of busting it.

I give it another try and see if I can't locate the serial number too.

Thanks again.

 

[ozflea]

Yes the plug covers become very hard and inflexable with age i see new ones on ebay occassionaly there much softer and you don't need a scewdriver to release them.

Mc Bob.

 

[Old Mac Guy]

Might help to take a broad- and thin-tip screwdriver and round off the sharp edges of the tip on your grinding wheel..... keep from chewing it up so much.... or use the old stand-by.... a popsicle stick....

I keep some flat-tip, sharpened hardwood sticks on one side of my workbench all the time.... pretty handy for lots of things....

 

[coveredinsap]

Hmmmm, thanks, I like the popsicle stick idea....less chance of buggering up the old plastic/rubber whatever the hell that cover is made of. Fragile stuff after 36 years or so.

I think the McEngineers were hungover on the day they dreamed up that spark plug cover

This 250 appears to be a .404 / .063 setup. I don't have the original chain, but I was able to clean up the original 20" hardnose Mac bar, and it appears to be useable. Any idea what the drive link count is on the .404 chain for the original 20" hardnose bar?

I think I read 65 drive links somewhere.....but I'm not sure if that is correct.

I'll post a few photos once I get it all cleaned up.

Thanks

 

[coveredinsap]

OK, I'll answer my own question....its 64 drive links

 

[cuttinscott]

Are you sure it's .063" gague and not .058" most ole macs I ever dealt with were .058"

Scott

 

[coveredinsap]

Well, its .063 now

 

[coveredinsap]

Photos as promised

Late model Mac 250 cleaned up and ready to go. Original 20" hardnose bar now running .404 .063 chain.

 

[coveredinsap]

Closeup bar photo

Here's one way to tell it's the original 20" bar. The other way was the yellow paint still remaining on the end of the bar prior to me sanding off all the rust. Boy was this bar a mess. Other than a nice layer of rust, it had a few dents and pinched areas in the rails, which were jam packed full of dirt. The rail edges were still relatively square though, so it was worth resurrecting from the grave.

 

[Lawn Masters]

Two things, that isnt just a late model 250, its the SUPER model, which has auto oiler, and is I believe 87 ccs instead of just 80 like the regular 250, and I'm curious, is that square ground chisel on the bar?

 

[ozflea]

Two things, that isnt just a late model 250, its the SUPER model, which has auto oiler, and is I believe 87 ccs instead of just 80 like the regular 250, and I'm curious, is that square ground chisel on the bar?

Hmmm how can you see if it's a Super 250 ? the only external difference are the super 250 had the rounded edge airfilter cover and if you remove the fuel cap you should be able to see the auto oil pump, plus the choke knob should be a depress and turn not a choke plunger.

This could be an early Mac 200 but i doubt that the origional bar for the Mac 200 had flying geese on it so the bar is possibly off something eariler 1-40 / 1-50, D-33.

Mc Bob.

 

[coveredinsap]

Yes, it's an automatic oiler (+ manual override) ....and square ground chisel chain.

Not sure whether it's the 87cc 'super' model or just the later model regular (super) 250, though.


As for the 'authority' thing, LOL! ...I'm sure there's a caveat in there somewhere

 

[coveredinsap]

I'm thinking the one I have is some type of early 'transition' model of the super 250, probably using leftover 250 parts. The bar was the yellow-tipped variety apparently from the earlier 250 model, as seen in these photos:
http://www.acresinternet.com/cscc.n...62d31fcbe77bee1b88256b610015c209?OpenDocument
...and the crankcase appears to have none of the listed serial designations for the 'super' model.

The markings/serial number on the underneath of the crankcase reads '250' (model number?) on the left of center, and '532' (serial number?) on the right side (looking at it from the underneath)....not consistent with either of the purported 'super 250' serial designations.
http://www.acresinternet.com/cscc.n...5fa50a1b8855469b88256c2f001aa843?OpenDocument

http://www.acresinternet.com/cscc.n...b8ec30eb359ff47588256b62001c6a41?OpenDocument

...of course, the acres site is not exactly the "be all, end all" for definitive information...so the serial numbering info could be mistaken.

Anyone else have one of the 250 or super 250 models, and how do the model number/serial number read on your version? Just curious.

Thanks

 

[coveredinsap]

model/serial photo

Here's what it looks like:

 

[ozflea]

To be truely sure of the engine size measure the stroke.

200.............................50659..............2.125"/ 1.375..............55009a.............80cc or 4.9 cu/in.................3
250.............................50659a............2.125"/ 1.375..............47782a.............80cc or 4.9 cu/in.................1
250 late.....................50659a............2.125"/ 1.500..............47903...............87cc or 5.3 cu/in..................1
Super 250.................60313..............2.125"/ 1.500..............47903...............87cc or 5.3 cu/in..................1
Super 250 ................50659a............2.125"/ 1.375.............47782a.............80cc or 4.9 cu/in...................1


Mc Bob....check my web site for more details.

 

[coveredinsap]

I'm not an engine specialist....is there a way to measure the stroke without removing the head?

 

[ozflea]

Easy but the quickest way, remove plug and insert length of wire measure the approx stroke marking the bottom of the stroke on the wire then rotate to top of stroke and mark again the gap between the marks represents the stroke.

Compare that length to the list above and presto you have it.

Mc Bob.

 

[coveredinsap]

Easy but the quickest way, remove plug and insert length of wire measure the approx stroke marking the bottom of the stroke on the wire then rotate to top of stroke and mark again the gap between the marks represents the stroke.

Compare that length to the list above and presto you have it.

Mc Bob.

Thanks

LOL! though....easier said than done, as the spark plug is mounted at an angle to the stroke of the piston.

Anyways, after numerous attempts to measure (and tossing out the wishful thinking in interpreting the results) it appears to be the 80cc version, as the stroke appears to be closer to 1 3/8" rather than the 1 1/2" required for the 87cc version.

In all actuality I suspected as much, as I had pretty much settled on the saw being this variety from circa 1970:
http://www.acresinternet.com/cscc.n...5fa50a1b8855469b88256c2f001aa843?OpenDocument

Thanks again for your help