McCulloch Super Pro 125c build thread

[Bigmac]

One final detail - on the left is the big bore saw and on the right is the standard SP I built earlier in the thread. The big bore saw has the wide handlebar that was designed
for the later saws that came with a chain brake. It uses an extension bracket to mount to the tank. Guys that have milled with 125s like the wider handlebar a lot more, as
it provides more room for accessing the clutch cover. I knew a guy that was using 125s to build a log cabin in BC years ago and he would run the wide handle with a cut-down
clutch cover. He wore out three saws by the time his cabin was done.

That’s cool, I have a wide wrap, but no bracket! I have wanted to try a modified cover on the sp, the cover doesn’t clear chips well I have thought about modifying a 250-300 cover, because they are cheap, I haven’t fit one on a 125 though, but have seen some guys run them, the back line is too vertical and too close to the clutch, I think it hurts in long bar use

 

[jacob j.]

That’s cool, I have a wide wrap, but no bracket! I have wanted to try a modified cover on the sp, the cover doesn’t clear chips well I have thought about modifying a 250-300 cover, because they are cheap, I haven’t fit one on a 125 though, but have seen some guys run them, the back line is too vertical and too close to the clutch, I think it hurts in long bar use

I think people mod the 250-300 covers a lot when running them on the 125s - I've seen quite a few.

I got a bracket for you for your wide handle. I think I have three extras.

 

[jacob j.]

The wide handle is the way to go if your gonna build a 125g. You need the extra width to clear the gearcase.

That's good to know Don - I'm thinking about building a gear-drive this winter. I'll probably use a stock SP motor.

 

[Bigmac]

I think people mod the 250-300 covers a lot when running them on the 125s - I've seen quite a few.

I got a bracket for you for your wide handle. I think I have three extras.

That would be cool!

 

[sawfun]

That's good to know Don - I'm thinking about building a gear-drive this winter. I'll probably use a stock SP motor.

I only know of McBob doing it. Bending the oil pump rod is the very tricky part, I've ruined one already ugh, with measuring the location of bends and the twists necessary. I am in the middle of a cp125g build, though have given thought to returning it to direct drive with today's prices. I have an sp125 that might be better suited. The cp's AV seemed easier to build around. McBob used a cut away sp oil tank as I recall. The gear drive stuffer needs material removed the same as when doing the 797g conversion. Make a front mount off of the steel plate behind the stuffer and your pretty well set.

 

[Lee H]

Also all the SP105's got the thinner side covers. All the sp125's I have had and seen all
had the wide covers. CP's had the thin ones like bigmac stated. The SP's with wide cover
also had a longer starter drive.

I like the early original logo way better than the new one.

 

[Lee H]

Jacob, A lot of 101 motors had aluminum side covers. They were the wide ones
especially the chrome ones since aluminum can be chromed as magnesium is
a pain to chrome and expensive.

 

[PogoInTheWoods]

A wonderfully enjoyable and educational thread, fellas. Thanks for sharing all the pics, knowledge, and experience. Very inspiring.

 

[jacob j.]

I thought you guys would enjoy hearing the big-bore saw running for the first time. It's a beast to pull over. I haven't put the compression tester on it but I'm guessing it's
right at 200psi. I have to change the tank though - this one has a slow leak on one corner.It's got the modified Promac 650 coil on it that my dad fixed up - I think I'll swap that out. The timing on it is super aggressive.

 

[Bigmac]

I thought you guys would enjoy hearing the big-bore saw running for the first time. It's a beast to pull over. I haven't put the compression tester on it but I'm guessing it's
right at 200psi. I have to change the tank though - this one has a slow leak on one corner.It's got the modified Promac 650 coil on it that my dad fixed up - I think I'll swap that out. The timing on it is super aggressive.

Sounds good! How much over bore?

 

[jacob j.]

Sounds good! How much over bore?

It's a .030" over cylinder with a new .030" over slug and rings I found on e-bay many years ago.

The 101 saw of my dad's is .020" over and I've got an Mc-91b motor to put in a 795 frame that's .040" over.

Somewhere in my stash I have a .050" over 101 block.

 

[jacob j.]

I didn't know if you guys had seen this action - this seller has a lot of NOS Mac stuff:

https://www.ebay.com/itm/Vintage-Mc...025773?hash=item1cd3e41a2d:g:gBAAAOSwumJdEZA3

 

[Bigmac]

It's a .030" over cylinder with a new .030" over slug and rings I found on e-bay many years ago.

The 101 saw of my dad's is .020" over and I've got an Mc-91b motor to put in a 795 frame that's .040" over.

Somewhere in my stash I have a .050" over 101 block.

That’s cool, over bore sp pistons are hard to come by now! I think Terry is making one for Mike in the cp, Mike would know better, I haven’t gotten one from him. The kart saw I posted the video of is .024 over, it was a worn out .020, and an original saw block, I bought a lot of parts on eBay and it came with a .024 piston and 101b rod. So only a hone to fit the piston! Terry has a ton of piston options for you if you need, .024 .028 and .030 I believe, the kart motor in my current build is .004 over.

how do you like that 91b/795?

 

[Bigmac]

I didn't know if you guys had seen this action - this seller has a lot of NOS Mac stuff:

https://www.ebay.com/itm/Vintage-Mc...025773?hash=item1cd3e41a2d:g:gBAAAOSwumJdEZA3

I have seen some of his stuff, but didn’t look up his seller page! He had a lot of stuff! The splined socket and recoil screen are nice! The mc49 reed are a perfect replacement for the 125, and $6!

 

[p61 western]

That’s cool, over bore sp pistons are hard to come by now! I think Terry is making one for Mike in the cp, Mike would know better, I haven’t gotten one from him. The kart saw I posted the video of is .024 over, it was a worn out .020, and an original saw block, I bought a lot of parts on eBay and it came with a .024 piston and 101b rod. So only a hone to fit the piston! Terry has a ton of piston options for you if you need, .024 .028 and .030 I believe, the kart motor in my current build is .004 over.

how do you like that 91b/795?

Yep Terry can make just about any piston you need. He tried buying the tooling to make rings, but they wouldn't sell it to him. He was not a happy camper lol. That said he has no problem getting the rings either. I need to get my azz down to his place soon. It's cool just bsing with him.

 

[Bigmac]

Yep Terry can make just about any piston you need. He tried buying the tooling to make rings, but they wouldn't sell it to him. He was not a happy camper lol. That said he has no problem getting the rings either. I need to get my azz down to his place soon. It's cool just bsing with him.

Ya you need to get there! This was your thread! Slacker! Lol

 

[jacob j.]

That’s cool, over bore sp pistons are hard to come by now! I think Terry is making one for Mike in the cp, Mike would know better, I haven’t gotten one from him. The kart saw I posted the video of is .024 over, it was a worn out .020, and an original saw block, I bought a lot of parts on eBay and it came with a .024 piston and 101b rod. So only a hone to fit the piston! Terry has a ton of piston options for you if you need, .024 .028 and .030 I believe, the kart motor in my current build is .004 over.

how do you like that 91b/795?

I'm looking forward to putting together the 91b/795. It was a race rig before - part of the tank was cutaway previously and it has a custom round tank that bolts on top. It has a stock bore 91b in it that's really tired. The block will need bored over - I'm sending it to Terry in about a month. I have a full-circle crank for it as well. I'm going to have Terry bore it out and match a piston for it. It has the vertical kart V-4 intake and a BDC carb on it. I'm gonna swap that out for a V-6 Christensen intake and twin HL-224s.

 

[jacob j.]

Yep Terry can make just about any piston you need. He tried buying the tooling to make rings, but they wouldn't sell it to him. He was not a happy camper lol. That said he has no problem getting the rings either. I need to get my azz down to his place soon. It's cool just bsing with him.

Ya you need to get there! This was your thread! Slacker! Lol

Yeah Mike, you need to get cracking and take back over your thread...

 

[p61 western]

Yeah Mike, you need to get cracking and take back over your thread...

Lol one of these days. I told Terry no hurry on it. Things got busy and hectic lol. Been running saws, but not working on them lol. Still got those 930 projects lol.

 

[Bigmac]

I'm looking forward to putting together the 91b/795. It was a race rig before - part of the tank was cutaway previously and it has a custom round tank that bolts on top. It has a stock bore 91b in it that's really tired. The block will need bored over - I'm sending it to Terry in about a month. I have a full-circle crank for it as well. I'm going to have Terry bore it out and match a piston for it. It has the vertical kart V-4 intake and a BDC carb on it. I'm gonna swap that out for a V-6 Christensen intake and twin HL-224s.

That will be cool! Looking forward to that! I have wanted to do a 100cc kart Mac too