Mcculloch sp125/101b kart saw build thread

[p61 western]

Got the WB 37 today, got it modded up to fit, fired it up and got it relatively tuned. It is 28 mm bore, and a 1 inch VenturiView attachment 239722View attachment 239723Got the WB 37 today, got it modded up to fit, fired it up and got it relatively tuned. It is 28 mm bore, and a 1 inch Venturi

Looks a bit small.

 

[Bigmac]

Looks a bit small.

Haha! Yes compared to the bdc it is!

 

[jacob j.]

Haha! Yes compared to the bdc it is!

It sounds pretty darn good though - good, crisp throttle response. Are you gonna stick with the GEM muffler for now?

 

[p61 western]

It sounds pretty darn good though - good, crisp throttle response. Are you gonna stick with the GEM muffler for now?

Agreed!!

 

[Bigmac]

It sounds pretty darn good though - good, crisp throttle response. Are you gonna stick with the GEM muffler for now?

I am going to do more testing on the mufflers, I noticed that the puck muffler I had on there was cracked at the base, and needs weld it up. But I also recently picked up a nice puck muffler, it’s the kart style without the mounting hole for the head, just not sure if I should weld around the base of it before I install it, this cart motor is really hard on muffler! LOL I also picked up a nice box muffler, so I can finally do a three-way shoot out! I’m also not sure if I’m going to make an adjustable outlet for the gem muffler to be able to tune it. I was actually able to get the gem muffler to run pretty well by the end of testing, I found out that need to be just on the edge of too rich to pull the best.

 

[Bigmac]

It sounds pretty darn good though - good, crisp throttle response. Are you gonna stick with the GEM muffler for now?

I am still learning with the saw, I’ve been messing around with tuning quite a bit, small changes in the tune can make a pretty dramatic difference, Like the eight screw is probably sensitive to the 16th of a turn, if it’s just a touch lean it loses a fair amount at torque, But will sound totally fine.
Also learning what it likes for load, I think I’d have to add another tooth on the sprocket to make it self feed better, I can dog down pretty hard and it doesn’t seem to mind too much, but the Oiler is at its limit or I have issues. I can have it so it’s dripping oil off the bar for a foot to foot and a half and it will dry up in the cut, the wood is really dry, even the 797 was having issues drying up.

 

[jacob j.]

Yeah my dad had a lot of issues with that and he used to cut the bar oil in half with diesel to help. He would complain about that though because in those days you could get a refill on
your 5-gallon bar oil jug for 50 cents a gallon but diesel was 79 cents a gallon at the time.

 

[Bigmac]

Yeah my dad had a lot of issues with that and he used to cut the bar oil in half with diesel to help. He would complain about that though because in those days you could get a refill on
your 5-gallon bar oil jug for 50 cents a gallon but diesel was 79 cents a gallon at the time.

That’s an awesome story! I will try and that.

 

[Lee H]

Sounds damn nice, I got to get on my trouble saw soon.

 

[Bigmac]

Realized I forgot to post the .404 8 pin video

I uploaded the one that the clutch backed off, dang right hand thread cranks! Lol

I was cutting into a big nasty spot to test it out, it actually held higher rpm in the harder wood, then the clutch backed off. I brought and impact, tightening it up and kept cutting.

This is still the wb3

 

[Lee H]

Shes a cuttin mofo fo sure.

 

[jacob j.]

I posted these years ago - an article on porting McCulloch kart motors from 1961 by Jim Butler. Jim was a premier kart engine builder/two-stroke tuner and
wrote hundreds of articles on building and tuning two-stroke engines.

 

[jacob j.]

 

[jacob j.]

The porting information is applicable to most or pretty much all Mac motors from that era.

 

[p61 western]

I posted these years ago - an article on porting McCulloch kart motors from 1961 by Jim Butler. Jim was a premier kart engine builder/two-stroke tuner and
wrote hundreds of articles on building and tuning two-stroke engines.

The porting information is applicable to most or pretty much all Mac motors from that era.

Cool stuff thank you for sharing the information Jacob.

 

[jacob j.]

Cool stuff thank you for sharing the information Jacob.

I got a lot more to post, I just need to chew my way through the archives. I followed the instruction in the article when porting a 125 block years ago and it turned out well.

 

[Bigmac]

I got a lot more to post, I just need to chew my way through the archives. I followed the instruction in the article when porting a 125 block years ago and it turned out well.

Cool, that was a good read!

 

[Bigmac]

Working on WB swap number two! This one’s going a lot faster than the first one!
No going back now

 

[p61 western]

Working on WB swap number two! This one’s going a lot faster than the first one!View attachment 241470View attachment 241471
No going back nowView attachment 241472

Using the 088 boot?

 

[Bigmac]

Using the 088 boot?

Nope
But I do use an 088 part on the intake