Mcculloch sp125/101b kart saw build thread

[Bigmac]

I got mine today as well - I have two older SPs that I rebuilt a couple years that are getting new boots.

Good insurance for sure! Before this you had to push your luck on a few builds to save stock, and lucky it hasn’t been an issue. After seeing them I will order more!

 

[Lee H]

I gotta get me a few as well.

 

[jacob j.]

After chatting with another member here last night about Mac Kart stuff, I decided to see if I could salvage some
of the stuff on McBob's old McCulloch website. This chart for 101s I believe was compiled by Steve O'Hara, a long-time
Mac engine guru.

 

[jacob j.]

Some more info:

 

[Lee H]

Nice info Jacob, Thanks for sharing.

 

[jacob j.]

Important notice regarding your piston's extended warranty from Wiseco:

 

[Bigmac]

Been messing around and rounding up parts. Made an appointment with my welder friend…got 2 kart cranks welded and some repairs on a wrap bars.did some finish work on them happy How they turned out. And I dressed up a really ugly set of bars with some heater hose, will be ok for a work sawHides some sin..

 

[Lee H]

I have welded up a few cranks as well. Had a couple weights fall off, Thank god not when they were running.

 

[Bigmac]

I have welded up a few cranks as well. Had a couple weights fall off, Thank god not when they were running.

All of the kart/early saw cranks I am having fully welded! Extra insurance! And am wondering if haveing the bolt on style welded would help them handle more. Have been a little nervous to try, and the epoxy they use may be an issue, makes me want to try un bolting one cleaning it and then bolt back and tig the perimeter would be the cats meow! lol

 

[Bigmac]

Made a small discovery when cleaning tonight, may others have noticed before? It looks like there is an early, and later style to the flywheel side bearing support.
Bottom is early style, my 797 has the same, the middle is the latter 125, and weighs a bit more than the early style and top is kart. I haven’t tested if the middle one is magnesium yet, don’t have any vinegar. Just wondering if anyone know when they changed?
See the casting change

 

[Bigmac]

Been working on an experimental head design. Most of the kart heads, have the 1/2 reach plug, I bought a lot of heads years ago, and I got some over milled heads. I decided to take a head that was milled over .100 of and inch! I decided to try and convert to to a 3/8 reach and open up the chamber, it’s a more modern style. Need to cc it to see were it is, is I went too far I can always mill more! Lol top head milled about .060 and bottom head is a 101aa stock head

 

[Bigmac]

So me being dumb, I forgot pickle jar juice is vinegar, so I remembered that and tested the parts, the new style is indeed aluminum.
So now I think the casting difference may just be to keep them easily identifiable, all of the reinforced style covers I have are aluminum, and I know many were in saws. There is a large weight difference too! 135+ grams
and all of the reinforced covers were within a few grams.

 

[Lee H]

If i'm not mistaken, The aluminum ones are 101 covers, Magnesium for saws to save weight. There is a huge
difference in weight, I can tell just by picking them up. I never notice the reinforcing.

 

[sawfun]

If i'm not mistaken, The aluminum ones are 101 covers, Magnesium for saws to save weight. There is a huge
difference in weight, I can tell just by picking them up. I never notice the reinforcing.

I REALLY noticed the mag vs aluminum difference when lifting a 14:71 off motors during maintanence. The aluminum blower definitely hurt my back.

 

[Bigmac]

If i'm not mistaken, The aluminum ones are 101 covers, Magnesium for saws to save weight. There is a huge
difference in weight, I can tell just by picking them up. I never notice the reinforcing.

That’s what I thought too, but I have 2 that appear to have been original saw covers. Both had factory yellow paint and were aluminum. Maybe someone painted them.was there ever a yellow 101 cover?

 

[Bigmac]

I REALLY noticed the mag vs aluminum difference when lifting a 14:71 off motors during maintanence. The aluminum blower definitely hurt my back.

I bet that’s a huge amount of weight in something that big!

 

[sawfun]

I bet that’s a huge amount of weight in something that big!

Yup, and I was 20 years younger then.

 

[Lee H]

That’s what I thought too, but I have 2 that appear to have been original saw covers. Both had factory yellow paint and were aluminum. Maybe someone painted them.was there ever a yellow 101 cover?

I don't believe there was ever a yellow 101 side cover. But if supply of the magnesium covers ran short
Mcculloch isn't going to stop production and could have possibly installed aluminum covers on saws.
Just a thought, happens all the time in the production world.

 

[Bigmac]

I don't believe there was ever a yellow 101 side cover. But if supply of the magnesium covers ran short
Mcculloch isn't going to stop production and could have possibly installed aluminum covers on saws.
Just a thought, happens all the time in the production world.

I agree completely! It makes sense. Just one more small thing to look for! And if anyone has a reinforced style cover in magnesium, post it up!

 

[Al Smith]

Just a thought, happens all the time in the production world.

On that I might mention the flywheel on one of my 125's being odd .The pull bolt holes believe it or not were size 12-24 bolts .Try finding those long enough for a bar puller . I did but broke one in the process .My cure was drilling them out to 5/16-18 .How or why they ever put tiny little threaded holes in a flywheel that large remans a mystery .Even at that I had to heat the center of the flywheel to get it off .