Mcculloch sp125/101b kart saw build thread

[Scott Kelsey]

Do you guys know what the welded on 101 weights are made out of or where I could get one? I purchased a small lot of 101 parts and have a good clean straight crank that is missing a weight that someone clearly cut off for some reason.

 

[Bigmac]

Do you guys know what the welded on 101 weights are made out of or where I could get one? I purchased a small lot of 101 parts and have a good clean straight crank that is missing a weight that someone clearly cut off for some reason.

Have you measured the rod journal on it? That’s probably why they cut them off. I also don’t know what it’s made off.

 

[jacob j.]

Do you guys know what the welded on 101 weights are made out of or where I could get one? I purchased a small lot of 101 parts and have a good clean straight crank that is missing a weight that someone clearly cut off for some reason.

Have you measured the rod journal on it? That’s probably why they cut them off. I also don’t know what it’s made off.

I can't speak to the 101 crank weights but I believe the 125 crank weights are Tungsten, or at least that's what a couple of old-school Mac technicians told me.

 

[jacob j.]

I was inspired Jacob, this what I came up with! Lol I am short on limiters too! View attachment 321774View attachment 321773 View attachment 321775
stated working on the av mount! Need some more washers. View attachment 321776View attachment 321777

Awesome Nathan, that one is gonna be a dandy...

 

[Scott Kelsey]

Have you measured the rod journal on it? That’s probably why they cut them off. I also don’t know what it’s made off.

I have not measured the rod journal yet. Does anyone have specs i could mic it out to? Just ran it on a dial indicator. I am assuming your saying the journal might be worn and thats why the one weight was cut off?

 

[Bigmac]

I have not measured the rod journal yet. Does anyone have specs i could mic it out to? Just ran it on a dial indicator. I am assuming your saying the journal might be worn and thats why the one weight was cut off?

.629/.630 is nos, below .628 it gets questionable, I don’t run them below.628. You can don’t want to ever run a worn rod and a worn crank, they apparently die pretty fast!

 

[heimannm]

 

[Bigmac]

Awesome Nathan, that one is gonna be a dandy...

Pretty excited to build a blue/red 101b setup! Surprisingly you don’t see that combo much. Think I am going to test modded stock intakes on this one, and leave the other 101 as a stock baseline.

 

[Lee H]

Nice info Mark

 

[heimannm]

Attached is the full "General Service Information" for the SP125 with the full "filmstrip".

Mark

 

[Bigmac]

Attached is the full "General Service Information" for the SP125 with the full "filmstrip".

Mark

Thanks Mark! I am going to print that out

 

[Bigmac]

Made some progress, but this one needs a lot of part to finish

 

[Bigmac]

Do you guys know what the welded on 101 weights are made out of or where I could get one? I purchased a small lot of 101 parts and have a good clean straight crank that is missing a weight that someone clearly cut off for some reason.

A bad crank can sometimes look pretty nice

 

[ferris]

A bad crank can sometimes look pretty niceView attachment 321982View attachment 321983View attachment 321984View attachment 321985View attachment 321986

What is bad with that crank?

 

[Bigmac]

What is bad with that crank?

The rod journal is undersized, it also has a few pits
New is .629/.630 this one is oblong and almost.005 under, but it doesn’t visually look bad. The crazy part
Is it cam out of a stock bore 101aa that had a piston that still measured as good, that block went .004 over.

 

[Lee H]

I can see the bad. Pitting is no good. I bet lack of or poor oil combined with the
high revs the 101's turn is what took that cranks life.

 

[smokey7]

Im sure calipers are good enough to tell you its bad or oblonged. But for real numbers id be using a mic.

 

[qurotro]

Finally got the clutch off today. Not looking really good. I think I need to replace the drum bearing at least. Bearing is SCE 910? A bit rusty in the marking I can't read really clear.

 

[jacob j.]

Finally got the clutch off today. Not looking really good. I think I need to replace the drum bearing at least. Bearing is SCE 910? A bit rusty in the marking I can't read really clear.View attachment 322023 View attachment 322024 View attachment 322025

Looks like your clutch has a bit of wear on it, which is normal - these are big saws and they do heavy work. I think Customchainsawparts still has clutches and drums available.

If you need a new bearing, I believe the Husqvarna 394/395 clutch bearing is the same dimensions.

 

[heimannm]

SCE910 is correct.

Mark