McCulloch Super Pro 125c build thread

[heimannm]

Thanks JJ, excellent information as always.

Mark

 

[jacob j.]

Here's the .010" over saw idling after first start-up:

 

[PA Dan]

Here's the .010" over saw idling after first start-up:

Sounds awesome!

 

[jacob j.]

Sounds awesome!

It's my favorite thing to fire one up after a full rebuild and have it just sit there and idle.

 

[jacob j.]

First cut with the .010" over saw:

 

[beaglebriar]

Nice!!! Love that idle.

 

[Lee H]

These 125's really suck don't they,

 

[jacob j.]

Starting in on yet another .030" over saw motor - this one I got in a big box of junk from a guy in Hillsboro in 2002. He had inherited the stuff from his grandfather, but then
decided the project was too much for him to take on. It was one of the dirtiest, nastiest saws I've ever gotten. The grandfather had been using the saw to rip reclaimed timbers
from the old Columbia river bridge. I'm sure they were Creosote treated (or similar).



The block is marked .030" over, but mic'ed out to be just under-sized for the application. I did some sanding to get things straightened out. The block had been needled in the
past and not completely cleaned up.

 

[jacob j.]

I spent about 90 minutes cleaning up the intake and inside the block. I hope I'm not polishing a turd...



It's in the hot tank now for about two hours...

 

[Frank bierce]

I spent about 90 minutes cleaning up the intake and inside the block. I hope I'm not polishing a turd...



It's in the hot tank now for about two hours...

Well, it looks good!!

 

[Lee H]

I like the piston Jacob and did you touch the intake ports behind the welch plugs.

 

[jacob j.]

I like the piston Jacob and did you touch the intake ports behind the welch plugs.

Hey Lee -

Yeah, I have long-reach double cut burrs and a long-reach sanding mandrel which allow me to reach those transfer nozzles on the opposite side of the cylinder. I've
always been a believer that the transfer nozzles should match the intake nozzles in size, shape, and timing. Borrowing from Randy, I push a ring up into the bore with
the piston to make sure everything lines up. If it's a high-hour block, I replace those welch plugs anyway. They're cheap and it's not worth risking an air leak on one
of those. It's hard to see here, but I've got an old ring at the top of the intake and transfer nozzles and everything is right on the money.

 

[jacob j.]

I'm pretty happy with the block after hot-tanking. It got most of the built-up crud off including all that Creosote or whatever it was. My hot
tank is 1/2 gallon of straight purple power with two tablespoons of Dawn dish washing soap in a big pot on low heat for about two hours.
It wrecks the factory paint if it's a painted block but the cleanliness is worth it.

 

[Lee H]

I have heard the same thing Jacob, That the ports from should match. Yours look good from what i can see.
Should make for a good runner. What comp do you think you will see with that piston. A good stock 125 is
usually around 180.

 

[jacob j.]

I have heard the same thing Jacob, That the ports from should match. Yours look good from what i can see.
Should make for a good runner. What comp do you think you will see with that piston. A good stock 125 is
usually around 180.

I'm hoping to hit 195-200 with this one Lee. I may put a totally different intake system on it. I'll start it out in stock configuration and see how it does. I may roll it
up later with a Reed 458 sloper manifold and an 084 carburetor.

 

[Bigmac]

I'm hoping to hit 195-200 with this one Lee. I may put a totally different intake system on it. I'll start it out in stock configuration and see how it does. I may roll it
up later with a Reed 458 sloper manifold and an 084 carburetor.

I bet she pulls a little more compression than that just looking at the dome, unless you raise the exhaust port a fair amount. It’s a pretty tall dome, I bet it gets into the 230 to 250 range, but could be wrong

 

[jacob j.]

I bet she pulls a little more compression than that just looking at the dome, unless you raise the exhaust port a fair amount. It’s a pretty tall dome, I bet it gets into the 230 to 250 range, but could be wrong

That'd be just fine with me....

 

[jacob j.]

I might do a little shaping on that dome though - I've been trying to brainstorm ways to make best use of the flame front.

A flat top piston is most efficient on that end, but I might shape a little flat spot facing the spark plug and then index the electrode.

 

[Bigmac]

That'd be just fine with me....

Ya, I don’t see a problem with it, I just am thinking it could get there! It might land somewhere in the middle too. Will be cool to see what happens!
I also would like to see your Frankenstein saw!

 

[Bigmac]

I might do a little shaping on that dome though - I've been trying to brainstorm ways to make best use of the flame front.

A flat top piston is most efficient on that end, but I might shape a little flat spot facing the spark plug and then index the electrode.

Ya I was thinking the same things! Lol