Mcculloch sp125/101b kart saw build thread

[dik650]

Good catch, haven’t seen a red factory fan shroud, so the 101b had a metallic red rear cover and the 101mc had a straight red with white fan shroud. The crank looks like the 3/4 101mc crank

This makes sense. The seller stated that the engine powered a "tri sport mac 3 wheeler", & that it had been stored for years. Is the 101mc similar to the a-d engines? I found a brochure for the trike & it lists the McC option as the 101A/A.

 

[dik650]

Got my engine. I've never seen something, anything, packed so thoroughly! There were layers of protection via tape & cardboard. It must've taken an hour or more to do!

Still not positive as to what model it is though I believe what I'm told about it being an m/c.
Haven't heard it run yet, but I'm sure it will. Compression feels okay. It should improve with some time.
I had a so-so 740 sitting under a pile of other yellow, so I decided to do some roughing in.
So far the only problem is the lack of space under the hood. The rear handle on the subject was fairly trashed with cracks so I cut it. Few more things to massage & it should be good to go sans crank. I'm going to look for another head cover to cut up, I'd like to keep the one that it came with intact.
Not sure what to do about a carburetor. Oh there's also the completely knawed away bar anvil, or whatever it's called. Couldn't find any tanks on the world wide web.

In other news, I'm going to be tearing my mc92 & 93 down. No point in not measuring everything before I run them/blow them up.. The 93 seems to have a large amount of crank walk, that I just noticed.

Oh BOY, I'm going to have these fun saws and not a darned thing to cut. Gonna have to do something about that...

 

[dik650]

More pics.
Also forgot to mention that the stuffer rubs which I was expecting. The kart stuffer is on it now. I'll begin the massaging at a later date. Got some other garboge to contend with first, though.

 

[dik650]

Last 2.
What a badass air filter. Very sturdy & quite orange!

 

[Bigmac]

Also forgot to mention that the stuffer rubs which I was expecting. The kart stuffer is on it now. I'll begin the massaging at a later date. Got some other garboge to contend with first, though.
View attachment 373327View attachment 373328View attachment 373329View attachment 373330View attachment 373331

What did the tag say the motor was? Mind posting a pic of it? I think I have some pics in the thread on the block mods for the manual oiler mods. Sometimes 2 stuffer gaskets can make the smaller stuffer fit.
I haven’t tested it yet, but i think the older saw head will fit under the stock back cover with minimal mods if any, I need to cc the head and test fit

 

[davidwyby]

@Bigmac thats weird. How did that post get over here?

 

[Bigmac]

@Bigmac thats weird. How did that post get over here?

Sorry about that, It wasn’t intentional

 

[davidwyby]

Sorry about that, It wasn’t intentional

No worries! Just cornfused first thing in the am

 

[dik650]

What did the tag say the motor was? Mind posting a pic of it? I think I have some pics in the thread on the block mods for the manual oiler mods. Sometimes 2 stuffer gaskets can make the smaller stuffer fit.
I haven’t tested it yet, but i think the older saw head will fit under the stock back cover with minimal mods if any, I need to cc the head and test fit

I'll post up a pic on Monday when I'm back around the saws.

 

[dik650]

What did the tag say the motor was? Mind posting a pic of it? I think I have some pics in the thread on the block mods for the manual oiler mods. Sometimes 2 stuffer gaskets can make the smaller stuffer fit.
I haven’t tested it yet, but i think the older saw head will fit under the stock back cover with minimal mods if any, I need to cc the head and test fit

Well, no tags. Doesn't look like there ever was one on there. Here is some test fitting, no go. The head cover has a tab on the lower left area that does not tuck under the starter cover. Also as you can see, the length is just a little too short. Even with different, smaller head. I'm not positive if the head pictured, either a 1-40 or a super 44a, I think. It fit, which I was not expecting given the difference in bore diameter. The two heads look the same as far as volume goes. I don't know where my horse shot supplies are, or I'd cc it.
Havent you fabricated a head cover? I might give that a try if I can't find a kart head cover.
I get some scraping with 2 gaskets stacked, don't think it will take much to clearance the rod bolts.
I saw your photos on the oiler passage. Shouldn't be a problem.
I've got a super 797 crankshaft that I want to use. Looking at the pto side, that m/c crank is a whole lot beefier than the tapered cranks. I rekon I'll need different bearings, seals too of course. Not sure yet. I am sure I've read such info before, just can't remember..

 

[dik650]

It lives!
Seemed to be doing well until I put it flyeheel side up, then it started climbing rpm big time!

Was not really planning on showing this sound only video, but it's pretty interesting. Didn't fluctuate PTO side up.
The carburetor is the wind vane governed flatback with a primer. The highspeed has a weird spring setup on it that wouldn't allow it to seat

I think I'll look for seals & a better carb.
Not sure if a sesl can make such a profound raise In rpm without stalling lean.

 

[dik650]

 

[dik650]

Hmmm

 

[heimannm]

Sounds to me like it ran out of fuel.

There are typically two seals on the flywheel side, one outboard to protect the points and one inboard to seal the crankcase, 53 & 54 in the illustration.



Mark

 

[dik650]

New one is on the bottom. The inner one is rock hard.
Should I be putting new rod bolts back in?

 

[Bigmac]

New one is on the bottom. The inner one is rock hard.
Should I be putting new rod bolts back in?View attachment 374729

Are they splined bolts? If this was supposed to be a fresh build, I would double check everything!

 

[Bigmac]

this is the best carb I recommend the hl324a with the shallow fuel inlet. It’s a good cheap upgrade

 

[dik650]

Yes, 6pt spline. I think it was supposed
to be an an hour of runtime but from decades ago. Will definitely check
Clearances & the flywheel seals.

 

[Bigmac]

Yes, 6pt spline. I think it was supposed
to be an an hour of runtime but from decades ago. Will definitely check
Clearances & the flywheel seals.

If I know the history of the rod bolts I will reuse some of the splined bolts. The Allen head ones are one time use only, and if any bolts have been over torqued they are junk. If the splines on the head of are even slightly missing the black coating, I consider them junk. If they have been tightened without a spline socket it’s really not proper, and could damage its strength

 

[dik650]

Gonna measure them. They're .750" new.