Mcculloch CP125 reborn

[leeha]

Drop the point gap to maybe 18 and try that. Did you try the timing light trick? I know where an article on that is.

I would like to see that article Randy. Do you think 2 thou on point gap
will make that much of a difference. Every 123cc Mac i have worked on
got set at .020 and never any problems.

Lee,
I looked at my CP flywheel, the only mark I see is the arrow pointing to the edge which would mark the break in the points for timing. I looked at the SP's I have and they have either a 1A or a 2 marked on them and all of them are single keyed....if that helps any.

I have looked at 4 flywheels including the one on the saw.
All are single key. two have a number 2 and one of those
also has a number 8. The other two have no numbers. One
is one the saw. If you use a straight edge across the flywheel
fins and go next to the line, the arrow point it will come into
the center of the key. All 4 flywheels are the same from what
i can see so far. I would like to see a detailed pic of a 5 degree
flywheel if anyone has one.


Lee

 

[Mr. Bow Saw]

What carb are using on there. Have you tried one off another 125 you know
works well. My CP 125 has SDC 20 on it. I know you said it was responding to
adjustments well. You have gone over everything ells rechecking it.
It shows in my carb book the CP 125 came with SDC 20 OR Tillotson HS 70A.

 

[cpr]

Diagnosing the no sparky on the 791 tonight. Somehow the points had opened to a huge spread even though I set them at .020 after they migrated the first time and the saw hasn't run since. Anyway, seems I have a bad condensor. While I had it off, I noticed the MC-91 flywheel is stamped "5" on the starter pawl boss just like one of my 101 flywheels. So here's your pics!

Looks just like the one you describe. I'll have to see about the P/N to verify if this is a 5 deg. wheel (looks like 57946).

EDIT: Couldn't find this specific P/N, but Marmax lists a 5 deg. wheel and their photo shows a stamped 5 in the same place as mine. Kudos to Mark, he's right. Now, how specificly you tell, I don't know. I'd have to pop another one off and look side by side at them.

View attachment 211229

 

[buzz sawyer]

Drop the point gap to maybe 18 and try that. Did you try the timing light trick? I know where an article on that is.

That would give more coil saturation but wouldn't that retard the timing?

 

[heimannm]

Ignition timing with a "timing light", I hope I have the pages in the correct order.

Mark

View attachment 211298

View attachment 211296

View attachment 211297

 

[leeha]

Nice info Mark, Doe's this method apply to
the larger Mac's as well.





Lee

 

[watsonr]

I've been told that all the points saws can be set using a timing light and this method. I think it would only vary if it was a two leg coil, but think that you could still get it to work the same. A very old friend of mine who is an old time saw mechanic that used and worked on a lot of Macs said this was the most accurate method and worked every time. He explained it to me the same way as in what Mark provided, having the diagrams to see really makes a difference.

 

[RandyMac]

I couldn't download Mark's stuff, is there a degree wheel involved?

 

[blsnelling]

I couldn't download Mark's stuff, is there a degree wheel involved?

You probably need to install Adobe Reader.

 

[watsonr]

No degree wheel. Just use a timing light and hook one end to the coil grounding wire and the other to the saw body. When the points are open the light is off and when they are closed the lights on. It should turn on when the arrow on the flywheel is pointing at the center coil leg.

 

[RandyMac]

That I have Brad, something is interfering, I'm blaming Charter Cable.

 

[heimannm]

That procedure will be correct for all of the large McCulloch saws with the horizontal cylinder and points up to and including the SP125.

Mark

 

[leeha]

I had some time today to mess around with this piece of junk.
I checked the carb again. Intake boot, etc. I then wanted to
try the timing thing. So i got out the multi meter and found the
points were braking where the center line on the flywheel was
just past the center lamination. Wow i thought, Timing is way
to late. So i pulled the flywheel and checked the points. Gap
was at .014. Not sure what happened but i had set them at .020.
Reset the points so they broke where the line is in the center of the
lamination. Seems to run much better with a lot more power.
Hopfully the compression will come up with some more run time.
Here's another video. The wood is very hard well seasoned oak.

Lee

 

[watsonr]

Saw is running much nicer, big piece of wood too!

 

[Danno]

Awesome restore and good entertainment for the read. Lots of good information all around in here. Consider me subscribed to see how this runs after break in. I'm most interested in seeing those compression numbers. 145 just seems too low and that's not something you addressed.

Wish I knew about the spray on bedliner idea for the cover. I used a texture spray with black topcoat for the Super 250. I don't expect it to hold up and the texture is too heavy.

 

[watsonr]

I don't think 145 is to low for that old saw. Most of mine are hovering around 140-155.

 

[Danno]

I don't think 145 is to low for that old saw. Most of mine are hovering around 140-155.

I just thought with new rings and a hone he'd be over 160 at least. I agree that it wouldn't be too low for an old used saw, but I figured this disqualifies it from falling completely into that old used category, lol.

 

[leeha]

I don't think 145 is to low for that old saw. Most of mine are hovering around 140-155.

Compression isn't really considered low, But compaired to my
other 123cc Macs it could be higher. My freshly rebuilt 797's are
definately higher. And two of my SP125's are at 175 each.
This CP has new rings and i'm hoping it gets stronger.




Lee

 

[watsonr]

I would think it might, but then again it may not, I wouldn't take it apart trying to figure out why....but that's just me.:smile2:

It didn't get a new cylinder did it, just honed?

 

[leeha]

Just honed. Bore was really nice to start with
mic'ed out nice as well.
I'm just gonna run it the way it is.




Lee