Mcculloch sp125/101b kart saw build thread

[Lee H]

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!

I have a bunch as well as a couple nos ones. I will look when i get home tomorrow.

 

[Bigmac]

Got the short block assembled last night and had some issues, took some time to figure out! Should have her running tomorrow! .004 over 101aa block

 

[Lee H]

That's a nice stock block. Those are getting harder to find. What issues did you have

 

[Al Smith]

Stihl 460 rescue saw D-handle .I use them myself .

 

[Bigmac]

That's a nice stock block. Those are getting harder to find. What issues did you have

The piston had a low spot in the casting, inside between the pin boss. It would cause the rod to lightly bind on crank pin, when leaning over to the flywheel side, the rod would slightly shift to the side, normal, but that casting flaw would want to push the top of the rod over and case a slight bind, it wasn’t much. Just driving me crazy! Just one more thing to double check before assembly! One of the other rods had a slight bur that a light sanding fixed. This .004 took some filing to fix. I took a while to figure out, took it apart several times, trying new and old needles, to see if was a clearance issue, though it was a bent rod or maybe a bad crank!!

 

[Bigmac]

got her fired up, she sounds good

 

[jacob j.]

Sounds awesome so far Nathan!

 

[Lee H]

Well ya can't hate that, Sounds great. Gotta love a 101 saw

 

[Bigmac]

Started working on the wb/cp125

 

[Bigmac]

Have a bunch of decisions to make, do more epoxy on the intake manifold, run bigger stuffer, and porting! I wheeled out the cp, and the timing is lazy on thr exhaust 165/127 the kart blocks usually fall at 180-183 and 127-130. Thinking the exhaust need a lift

 

[Lee H]

There ya go, Lets be creative, Nice job. I did a 101 in a 125 chassis using the HL360 carb
and had nothing but trouble, Thinking about going a different route with the WB carb
just haven't the time to get back on it. This will give me a bit of motivation.

 

[Scott Kelsey]

I have a question for you guys out there that know the 125's. I have a SP125c and I am not sure if the rod is bent or if it is another issue such as worn needle bearings, etc. Is it possible I can have the block bored out and get a 101 rod and oversize 101 piston from Terry and have the block chromed by U.S. Chrome? In the attached picture you can see the rod is holding, even during rotation, to the exhaust side of the block/crank. Thanks for any input.

 

[Bigmac]

I have a question for you guys out there that know the 125's. I have a SP125c and I am not sure if the rod is bent or if it is another issue such as worn needle bearings, etc. Is it possible I can have the block bored out and get a 101 rod and oversize 101 piston from Terry and have the block chromed by U.S. Chrome? In the attached picture you can see the rod is holding, even during rotation, to the exhaust side of the block/crank. Thanks for any input.

It’s probably catching on some pealing plating. Yes boring and oversized plating is possible, and a 101 rod and piston will fit, assuming the bore is correct. Terry might have oversized pistons for your rod as well.
You might have to find a dealer to work with to get the plating done. Also from my understanding it’s pretty expensive, $3-400 plus about $200-250 for a kart rod and piston
Have had millennium do open cylinders and it usually runs 300, plus shipping, and that not bored, haven’t had a used cylinder that didn’t need the bore welded to go back to stock, so that can add too

 

[Lee H]

Scott, It looks like the crank may not be in all the way plus you don't have the
side case on yet to hold the crank straight, guessing why the rod wants to favor
the one side.

 

[jacob j.]

I agree with Lee - you need the ignition backing plate installed in order for the crank to be held true, that's why you never torque the rod bolts until
after you've installed the backing plate/side plate, because otherwise you won't get an accurate torque seating. Install the side plate and then see how
it turns over. Nathan might be right if there's flaws in the plating. Over the years, I've pulled apart about 30 SP-125c motors and only two still had
good chrome. That's why I have huge box of cylinders needing re-plated.

 

[Scott Kelsey]

Guys, thank you very much for the replies. I most likely won't be able to work on it till Christmas. I will put the side plate on it and see what it does. I was looking at the SP125C ipl earlier and am curious. Does the chrome bore models have a caged needle bearing for the wrist pin? That is what I see per the ipl but when looking up the part number on Ebay I find loose needle bearings.

 

[Lee H]

Loose needles is all i have ever seen on any of the 125's i have had apart
with the washers. One washer on each side of the rod.

 

[jacob j.]

As far as I know, the SP-125 only used loose needles on either end. Double-tapered needles on the big end of the rod, and cylindrical rollers on the small end, and then
as Lee said, thrust washers on the small end of the rod.

 

[Scott Kelsey]

Thanks!

 

[Bigmac]

Dis some max porting on an oem
Intake manifold, want to have around 4 versions of the oem manifold in different port styles.