These aren't near that large.
Building a SP125C / 101B Kart Saw
- Thread starter blsnelling
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These aren't near that large.
Dennis Cahoon
Addicted to ArboristSite
Just make an aluminum plate in the shape of your reed gasket for a little rise. You might have to replace your studs for more lenght.
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cpr
Addicted to ArboristSite
Must
Cause
Confusion
Using
Lots &
Lots
Of
Crazy
Hardware
:bang:
EDIT: I figured it out. Like all good sarcasm, there's some truth at work here. Continues over on my build. Sorry for the hi-jack Brad.
Cause
Confusion
Using
Lots &
Lots
Of
Crazy
Hardware
:bang:
EDIT: I figured it out. Like all good sarcasm, there's some truth at work here. Continues over on my build. Sorry for the hi-jack Brad.
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ozflea
Good ol' BP Zoom 25-1
Still wont make a difference using a spacer plate cause the fuel tank wont fit properly.
Just see if you can angle the lower edge of the pump section of the carb i didn't have any problems doing mine and i have done a couple.
McBob
Dennis Cahoon
Addicted to ArboristSite
No matter how yours fits McBoob it's a hack job at best. I think he's trying to make his look nice and have everything work.
ozflea
Good ol' BP Zoom 25-1
Well at least mine goes and goes well same as young Neils i built both
McBob.
McBob.
I finally got around to making some good progress on this first 101B cart saw I started. I promised the owner I'd have it done by Spring, and Spring's here! I put it together before painting all the bolt on parts to make sure it ran good first. I was not disappointed! What a relief to see this old beast purring again. I've NEVER seen compression like this thing has. It takes two of use putting our feet on it to start it! Wow. Throttle response is lightning quick. I've already got it torn back down for paint. It won't be bad, since the case side cover and oil tank were painted before assembly. The engine stays intact. By the weekend, I hope to have it finished.
[video=youtube_share;ZWfh3dH0_Lk]http://youtu.be/ZWfh3dH0_Lk[/video]
[video=youtube_share;ZWfh3dH0_Lk]http://youtu.be/ZWfh3dH0_Lk[/video]
I put a kit in the Walbro SDC carb that came of the other SP125 that will be my personal saw. The fully adjustable L and H needles are a must have on a conversion like this. I'm amazed how easily this thing starts, and the electric like throttle response! The other one will probably get a Tilly HL carb and a lot more modding. The engine in this one is a stock rebuild 101B.
parrisw
Tree Freak
Wow, that sounds good. I need one! White finger here I come!
Good to see you back on it Brad. These are awesome saws. Wait till you make some cuts with it...... I highly recommend the drop start method.
[video=youtube;imVCsFHAx-g]http://www.youtube.com/watch?v=imVCsFHAx-g&list=UULrY2h5eSXnXFiDgP_AaseA&index=15&feature=plcp[/video]
[video=youtube;imVCsFHAx-g]http://www.youtube.com/watch?v=imVCsFHAx-g&list=UULrY2h5eSXnXFiDgP_AaseA&index=15&feature=plcp[/video]
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Good call holding out the starter handle when shutting is off. You can always tell the good motors by the way it snaps the handle back.
I now know why guys do that. It REALLY grabs that handle when it shuts off.
McCulloch "Kick-Proof" starters
"Hello. Welcome to Shop Talk!":msp_biggrin:
A number of the very early McCulluch saws had a feature that was advertised as a "Kick-Proof" starter, just for that very reason. The first time I read that, I thought they were actually referring to some graceful person, like myself, blessed with big feet.
It is a interesting, & definetely an old-school design. The starter pulley shaft fits inside a tightly wound coil spring. (This spring is completely separate from the regular starter spring every saw has.) The coil spring itself is made up of square wire & kind of resembles a speaker voice coil. This spring with the starter shaft, inside the center of it, fits tightly inside the starter housing. You may have to work at it to get it in place. The shaft will spin when the starter handle is pulled. If the saw should happen to kick back, the spring around the starter shaft tries to unwind itself. When it does, there is no physical space for this spring to really go anywhere, so it just clamps on down the starter shaft and against the starter housing. You might think of it as a sort of chain brake for the recoil. The big tip: If you ever have the pleasure of disassembling a Kick-Proof starter, you probably will not be able to pull the pulley & shaft assembly straight out of the housing. I did, on a 3-25, & stretched the snot out of the coil spring. You actually have to twist it out, and it will only twist in one direction. Which one? You'll see.
"Hello. Welcome to Shop Talk!":msp_biggrin:
A number of the very early McCulluch saws had a feature that was advertised as a "Kick-Proof" starter, just for that very reason. The first time I read that, I thought they were actually referring to some graceful person, like myself, blessed with big feet.
It is a interesting, & definetely an old-school design. The starter pulley shaft fits inside a tightly wound coil spring. (This spring is completely separate from the regular starter spring every saw has.) The coil spring itself is made up of square wire & kind of resembles a speaker voice coil. This spring with the starter shaft, inside the center of it, fits tightly inside the starter housing. You may have to work at it to get it in place. The shaft will spin when the starter handle is pulled. If the saw should happen to kick back, the spring around the starter shaft tries to unwind itself. When it does, there is no physical space for this spring to really go anywhere, so it just clamps on down the starter shaft and against the starter housing. You might think of it as a sort of chain brake for the recoil. The big tip: If you ever have the pleasure of disassembling a Kick-Proof starter, you probably will not be able to pull the pulley & shaft assembly straight out of the housing. I did, on a 3-25, & stretched the snot out of the coil spring. You actually have to twist it out, and it will only twist in one direction. Which one? You'll see.
jra1100
Addicted to ArboristSite
Stupid question I'm sure, but if the 101 and the stock 123cc engine are the same displacement, why can't the stock engine be modified to the same specs as the 101. As you can tell I have never had mine apart to the extent that these have been. I'm not sure that I'd want all that much more power anyway, and as Brad pointed out, they are a bear to start anyway. JR
The 101 has a removeable head which allows for a large increase in compression. It also has more aggressive port timing from the factory.
The 125 has a fixed head with a large combustion chamber and more sluggish port timing. Porting the old Macs is much different than
porting a modern saw like a 372. They're a loop scavenge design reed-valve saw. The 125 can be made into a great runner but it will
still have the compression issue.
stinkbait
Addicted to ArboristSite
As long as you wouldn' t have to raise the exhaust port to get the timing numbers you want, there shouldn't be any compression issues. You could always weld a pop on the 125 piston to move compression up as well. If I had more than one 125, I would port one.
ozflea
Good ol' BP Zoom 25-1
Try starting a SP125 without using the decomp and you'll understand that both the SP125 and 101 are bears and big nasty bears at that
McBob.
McBob.
Also, the 101b has a steel sleeve, so it can be overbored like a car engine. There are aftermarket pistons up to .060 over which pushes the displacement to over 130 cc's. Overboring the cylinder is very easy because of the removable head. It does not require a bottom bore, which is much more difficult. Combustion chamber stays the same, so compression ratio goes up as well. One of my saws is .050 over, which is 129cc I think.
Anyone have a flywheel key for a 125? How about a front lower AV mount, the one on the bottom of the wrap handle? I also need a coil for that will work on the 101 block.
The first saw is in primer. I'll be shooting the color here shortly.
The first saw is in primer. I'll be shooting the color here shortly.
