McCulloch Super Pro 125c build thread

[jacob j.]

I'm starting in on another full build as well - this block has an interesting story. It's bored .030" over and came from a truckload of stuff I got from a faller in Bridge, Oregon in 1999.
He was going through some hard times (divorce) and was in desperate need of a newer big saw for a job he was cutting on Seneca ground for Whitaker logging near Camas Valley.
I traded him a new 066 with a 42" bar and chain for a whole truckload of Mac 125 and Pioneer P-60/61/62 carcasses and parts. He said the McCulloch stuff belonged to his uncle
who was a faller back in the day but had passed in the late '80's.

 

[jacob j.]

I found a new .030" over SP piston and rings on e-bay at the time. The block is unusual in that it is an SP block with a steel sleeve but has no ID numbers.

It's stamped "64" on one side and ".030" on the other side. I mic'ed out the block before fitting up the piston and the .030" over slug was a perfect fit.

 

[jacob j.]

I also had to clean and sort some fasteners today.

 

[Bigmac]

I found a new .030" over SP piston and rings on e-bay at the time. The block is unusual in that it is an SP block with a steel sleeve but has no ID numbers.

It's stamped "64" on one side and ".030" on the other side. I mic'ed out the block before fitting up the piston and the .030" over slug was a perfect fit.

That is interesting, have heard that guys could order up overboard cylinders brand new. My sp125c was originally a regular 125, but got swamped over to chrome, all off my chrome cylinders have no numbers at all. Do your standard sp125 cylinders have any numbers

 

[jacob j.]

That is interesting, have heard that guys could order up overboard cylinders brand new. My sp125c was originally a regular 125, but got swamped over to chrome, all off my chrome cylinders have no numbers at all. Do your standard sp125 cylinders have any numbers

I think all of my "regular" SP blocks are numbered, or at least those that came in saws new from the factory. I have also heard guys could order oversized blocks as a new replacement part. Marriott's saw shop
was installing .050" overbores for guys in the mid-70's with the Wiseco piston and rings. The stuff I got in this load was just a mish-mash of everything you could think of. There was even an Mc-20 motor
in a Super 44 frame. The guy said his uncle used the 125s all the way up until he got out of cutting in 1989. I guess there were guys in Alaska even running them into the late '90's.

 

[Al Smith]

Over bores have been kicked around for a long time .Back in the glory days if I'm not mistaken Wiseco and others made up to 100 thou over pistons .How much cast iron would left in the bore I have no idea .If it were too thin about the only thing I can think of is using 4140 steel for a sleeve like used in aircraft cylinders .4140 is tough vanadium steel but it's much harder to get a good smooth finish like fine grained grey cast iron .Not impossible by any means however .
As far as that,also in the glory days a few made stroker cranks too .Finding one would be like looking for a needle in a hay stack though these days .

 

[Bigmac]

Over bores have been kicked around for a long time .Back in the glory days if I'm not mistaken Wiseco and others made up to 100 thou over pistons .How much cast iron would left in the bore I have no idea .If it were too thin about the only thing I can think of is using 4140 steel for a sleeve like used in aircraft cylinders .4140 is tough vanadium steel but it's much harder to get a good smooth finish like fine grained grey cast iron .Not impossible by any means however .
As far as that,also in the glory days a few made stroker cranks too .Finding one would be like looking for a needle in a hay stack though these days .

Have heard the .100 as well, have seen .070 and .090 on eBay, Terry only sells up to .060 I believe, I think he feels that’s the max, safe bore, some blocks could have the liner offset or misaligned. I have one 101 that’s 60 over, and it getting thin

 

[Al Smith]

I think the largest I 've seen on flea bay was 90 over and that was with no rings which could be another problem with this puzzle .

 

[Lee H]

There was a guy on here a few years ago in Florida. I think his name was Brian was rebuilding a 797 and found a 100 over piston.
Can't be much left of the iron bore after that. I have a Super 797 that came to me from the west coat that
had a 70. over. Thank god the piston was good. That saw got a full restoration and runs well. Has a different
sound over a 797 with a smaller bore.

 

[jacob j.]

Got some starters serviced this weekend - it took a lot of work. I had to use wire brush attachments in my air die grinders to get all the gunk and pulverized sawdust out of them.

I got lucky a few years ago and got in on a buy for some re-pop starter handles that the kart guys were doing. They're good quality.

I don't know about you guys but I've always liked the old school McC logo more than the newer logo. Whoever designed the new logo was a complete twat.

 

[Bigmac]

Got some starters serviced this weekend - it took a lot of work. I had to use wire brush attachments in my air die grinders to get all the gunk and pulverized sawdust out of them.

I got lucky a few years ago and got in on a buy for some re-pop starter handles that the kart guys were doing. They're good quality.

I don't know about you guys but I've always liked the old school McC logo more than the newer logo. Whoever designed the new logo was a complete twat.

Looks good! The larger rubber ones are nice!! I am liking the Stihl d handle a lot nowadays

 

[jacob j.]

I had to make some new SP-style exhaust gaskets. This is the earlier large-style that I'm a fan of. The later style only covered the front two exhaust mounts and the exhaust port.

As we all know, parts are getting really hard to find for these old beasts, so we'll have to make more of this stuff by hand or have re-pops done.

 

[jacob j.]

Got'em mounted up on the saw that I built earlier in this thread and the big-bore saw I'm building for myself currently. They're not perfect but with a couple hours of heat
and vibration, they'll settle right in. The paper I used for this is high-heat thick gasket paper available at NAPA. It's stiff and more difficult to work with but it resists heat very well. In fact, I threw some small pieces on a brush fire I had going next to the drive way today and it took several minutes for it to catch fire.

 

[jacob j.]

I wanted to show you guys some differences between the starter shrouds. I think the later style is on the left and it has cast-in threaded bosses so you don't have to mess with
epoxying in retainer nuts. They're also a different "thickness." I think there was a post about the early saws not having enough air circulating around the engine so the shrouds
were changed along with re-designing the cylinder so that it has more and thinner cooling fins.

 

[jacob j.]

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.

 

[Bigmac]

I wanted to show you guys some differences between the starter shrouds. I think the later style is on the left and it has cast-in threaded bosses so you don't have to mess with
epoxying in retainer nuts. They're also a different "thickness." I think there was a post about the early saws not having enough air circulating around the engine so the shrouds
were changed along with re-designing the cylinder so that it has more and thinner cooling fins.

The 797 and cp125 got the short cover, and the sp got the long cover, I don’t believe any sp’s got the short cover, but could be wrong. There are also 3 different clutch covers on the cp and sp125’s

 

[Steve]

Got some starters serviced this weekend - it took a lot of work. I had to use wire brush attachments in my air die grinders to get all the gunk and pulverized sawdust out of them.

I got lucky a few years ago and got in on a buy for some re-pop starter handles that the kart guys were doing. They're good quality.

I don't know about you guys but I've always liked the old school McC logo more than the newer logo. Whoever designed the new logo was a complete twat.

The square McC is by far my favorite of the mac logos too. The goose is pretty cool too.

 

[Bigmac]

Cp125 then early sp125 and chain brake cover
The cp cove has no mount for a falling dog

 

[jacob j.]

The 797 and cp125 got the short cover, and the sp got the long cover, I don’t believe any sp’s got the short cover, but could be wrong. There are also 3 different clutch covers on the cp and sp125’s

Ok, that must have been it then - I couldn't remember the details. I know there were some SP covers that used the epoxied-in retainer nuts and the ones that had the cast-in bosses.

 

[sawfun]

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.

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