McCulloch Super Pro 125c build thread

[srcarr52]

Carb's are gas carb's and running AV gas. No matter what I did it would run out of gas at an idle.
Take the carb apart and it would be empty.

Did you run an external pulse line or were you using the pulse from the intake bore?

 

[Lee H]

Did you run an external pulse line or were you using the pulse from the intake bore?

Through the intake, Thought about doing the external line but just got to frustrated
with this saw and shelfed it. I need to get back on it again.

 

[Bigmac]

You guys have me all worked up about this now, so I'll try the RWJ-4 and SDC-80 this weekend
and see if that bumps up a stock 125.



Don - I have an external pump I was thinking about using with an older large-bore HL carb that only has the single-stage pump.

That’s cool, glad your worked up! Let us know how it goes!

 

[rogue60]

A mate got given this CP 125 few months ago.
I told him it's a nice looking original saw and he would probably get good money for it if he sold it.
He said he's going to keep it (even though he doesn't own or use chainsaws) he likes the sound piss revving it in his backyard lol

 

[Bigmac]

A mate got given this CP 125 few months ago.
I told him it's a nice looking original saw and he would probably get good money for it if he sold it.
He said he's going to keep it (even though he doesn't own or use chainsaws) he likes the sound piss revving it in his backyard lol
View attachment 199833

That is a nice looking saw! I like the way 101’s sounds too

 

[Definitive Dave]

Lee - were you running gas or methanol? Most of the 360s I've seen are methanol carbs.

360A = GAS
360B = METHANOL

 

[srcarr52]

Through the intake, Thought about doing the external line but just got to frustrated
with this saw and shelfed it. I need to get back on it again.

Convert it to an external pulse from the crankcase. The intake port only gets the vacuum side of the pulse because of the reed valves, those pumps really need the pressure side also to pump fuel well.

 

[Lee H]

The hole goe's into the crankcase side of the reed. That's why I never did
the external pulse line.

 

[srcarr52]

The hole goe's into the crankcase side of the reed. That's why I never did
the external pulse line.

Hmm. Stumped I am.

 

[Stump Shot]

I would hazard to guess that a two stage pump could be put on a HL. I know HR's will pump enough for the smaller single cylinder snowmobile engines in the 250cc range and pull a few feet and up a foot, larger singles and all twins went to a two stage.
A Mikuni single outlet pump could be an easy to do thing and they pump lots of fuel, enough for a 440cc twin.
Just some thoughts, carry on.

 

[Lee H]

Hmm. Stumped I am.

Me too. Why I gave up a few years ago.

 

[Bigmac]

Me too. Why I gave up a few years ago.

Any chance the impulse hole is partially blocked? Gasket or sealant covering the port

 

[Lee H]

Any chance the impulse hole is partially blocked? Gasket or sealant covering the port

Nope, Had this saw apart a dozen times and it sucks cuz you need to
remove full wrap and fuel tank to get carb out. Pain in the arse. I'll get
back to it soon. Thinking of trying a big Walbro RC carb. Don't want to
get into the Mac BDC carb as they are a very tight fit.

 

[sawfun]

Nope, Had this saw apart a dozen times and it sucks cuz you need to
remove full wrap and fuel tank to get carb out. Pain in the arse. I'll get
back to it soon. Thinking of trying a big Walbro RC carb. Don't want to
get into the Mac BDC carb as they are a very tight fit.

Removing the tank ever time, is exactly why my BDC saw sits.

 

[Bigmac]

Nope, Had this saw apart a dozen times and it sucks cuz you need to
remove full wrap and fuel tank to get carb out. Pain in the arse. I'll get
back to it soon. Thinking of trying a big Walbro RC carb. Don't want to
get into the Mac BDC carb as they are a very tight fit.

Have you done a pressure/vac test? Have you tested the carb on one of your other easier to work on saws to see if it was just a bad carb? I do that with other carbs, to eliminate variables, I always tests a carb like a demon/Holley on a running motor before I throw it on a fresh build so I don’t fight it. On my sdc20 saws on a fresh build I pull a runner carb and get it going first before I try the carb, or try the untested carb on a runner to check before I put it on the intended saw.

 

[Lee H]

Have you done a pressure/vac test? Have you tested the carb on one of your other easier to work on saws to see if it was just a bad carb? I do that with other carbs, to eliminate variables, I always tests a carb like a demon/Holley on a running motor before I throw it on a fresh build so I don’t fight it. On my sdc20 saws on a fresh build I pull a runner carb and get it going first before I try the carb, or try the untested carb on a runner to check before I put it on the intended saw.

Pressure tested several times, Tried a regular universal HL with 1 inch bore and saw ran fine.
Tried 2 different 360 carbs and both ran like crap with the same symptoms.

 

[Al Smith]

I could get you some info except one of them is dead and the other suffered stroke this spring .I've mentioned them before .Kenny Burden who is in the Talledaga hall of fame and Louis Baughan who is was in apprenticeship with and was national number 2 in the AGKA in the 70's and perfected the slide pipe .In conversation years ago Louis had mentioned Mikuni on 101's but I doubt it could be stuffed under the air box cover of a saw .
I've got a couple of Mercury outboards in my shop that have Tilly impulse carbs ,on for each cylinder, twins .Something like that might work ,don't really know ?

 

[srcarr52]

Pressure tested several times, Tried a regular universal HL with 1 inch bore and saw ran fine.
Tried 2 different 360 carbs and both ran like crap with the same symptoms.

We tried a lot of different carbs on our alky kart motors (briggs 5hp and honda gx200) and finally decided the bigger venturi just doesn't work. The 304 made .5hp more on a dyno but on the track the 334 would feel much better and beat the 304 off the corner every time.

 

[Frank bierce]

Yeah, when you go into shops these days it's all business and they don't want people hanging out - the attitude is you need to spend your money and leave.

Another of the local shops for years had an antique Pepsi cooler that they kept filled with Pabst and Coors - 50 cents a pop. All the log cutters would hang out
there after work. The parking lot would be full of square bodies and F-250s. I think when I retire I'll open a shop and have it be a place where guys can just
hang out and BS.

I’ll be there!!

 

[huskyboy]

Has anyone tried a Wj39, Wj70 or Wj71 off a 394xp on a 125? I imagine it would be easier to source than a sdc 20. It’s got internal impulse and it is is larger than the tillotson HS fixed jet carb. Problem is the linkage, maybe linkage from a 066 Wj could work... I was tempted to investigate that but the 125 is no longer here to try that . The fixed jet carb actually ran pretty good in cold weather though to be honest, just too fat in hot weather. Plus it kind of takes some of the fun out of it not being able to fiddle with the carb adjustments looking for that bit of extra powa. Lol