Building a SP125C / 101B Kart Saw

[cpr]

Keep running it up! The sooner the better. I'll sell the lot and be tractor pulling in the spring :hmm3grin2orange:.

 

[Jacob J.]

Jim Butler is the grandfather of Mac engine building and was probably the most knowledgeable kart engine enthusiast ever.

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[Jacob J.]

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[Ambull]

I decided to scan a great article from the old Karting World magazine on porting of the Mac kart blocks. This is kind of a long-winded article but has some great, great info on porting these blocks. I highly recommend anyone who intends on modifying one of these to read this.

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You are missing the middle two pages. Actually they are probably here on one of these posts somewhere.

 

[Jacob J.]

You are missing the middle two pages. Actually they are probably here on one of these posts somewhere.

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[boda65]

Jim Butler is the grandfather of Mac engine building and was probably the most knowledgeable kart engine enthusiast ever.

That $100 price tag is appealing, but adjusted for inflation equals $720 in 2010 dollars. I too am drooling over all these kart engine builds. I know how my SP105 runs, I can only imagine how a SP125 or 101 equipped saw would feel. Yee Ha!

 

[ausneil 1]

Lee won't need a piston with this one Brad.......just move compression release, add parts and paint!.......Yeeeeeehaaaaaa!

Is that where the decom normaly is, havn't seen one up there.
Then again i no nothing about kart engines.

 

[cpr]

No, not from the factory. I've seen a few with one drilled there, though.

 

[blsnelling]

Anyone ever seen a dual carb setup on a V4 sloper?

 

[cpr]

That's different. Never seen one on a sloper or oreintated that way...

 

[blsnelling]

I wouldn't think a V4 would flow enough for dual carbs.

 

[leeha]

I have never seen an intake like that either.
Strange set up.

Jacob, Nice info you provided. Thanks




Lee

 

[blsnelling]

Just seems to me, that if you want to run dual carbs, you'd want a V8, V12, or V16.

 

[blsnelling]

Jacob, thanks for the article.

 

[Freehand]

Real good stuff JJ,thanks.


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[Arrowhead]

Awesome info getting posted here!

I got yellow fever now, just need to save up a little more green.

 

[Jacob J.]

Just seems to me, that if you want to run dual carbs, you'd want a V8, V12, or V16.

Yeah, you need the reed area of at least 8 standard Mac reeds to take advantage of the flow characteristics that dual HL carbs can provide. Jim Butler did an article (which I'll try to find) where he flow-tested the common 4-6, 8, 12, and 16 reed manifolds and found that only 8 and above provided the CFM necessary to take advantage of twin HL-187a carbs. The 187a was an early HL performance carb which could be tuned to run either gas or methanol and it's a lower performance carburetor than the current 300-series carbs available today.

Real good stuff JJ,thanks.

There's a reason I didn't embed those pictures. They're quite large and some of the people interested in this thread are still on dial-up.

 

[Freehand]

Sorry JJ,just attempting to put them in order.Dial-up guys: It's worth the wait.

 

[Dennis Cahoon]

Anyone ever seen a dual carb setup on a V4 sloper?

Here's a portion of my manifolds......but looks like the slopers are straight, one dual and one single. I like the V-12 reed with the a big single burris mikuni or the twin tillitsons. The twin set-up can be alittle harder to tune. These are 4-sale.....with Leeha and RiverRat getting first choice......Don't even ask Brad!.......Hahahahahahaha!

 

[little possum]

Uncle Dennis, Ill take the ugliest, slowest, piece you can make run