Building a SP125C / 101B Kart Saw

[Dennis Cahoon]

Another National winning kart builder is Dave Liberton, from Phoenix AZ. I bought 2 stock 101B's from him in the 90's that came off Israeli drones. I also bought his personal 101B that he won a national race with. He claimed it dyno'ed at 22hp.

 

[RTK]

Thanks for the help and pointing me in the right direction guys

 

[rwoods]

Another National winning kart builder is Dave Liberton, from Phoenix AZ. I bought 2 stock 101B's from him in the 90's that came off Israeli drones. I also bought his personal 101B that he won a national race with. He claimed it dyno'ed at 22hp.

I would be thrilled to get 15hp from my toy saw. Can this be done with stock ports, gas and a kart muffler? I don't know what the stock rating of a 101B is, but some areo application charts listed them at 15hp - I would have thought 10. Ron

 

[blsnelling]

More goodies showed up today.

Are there better aftermarket reeds?

Is this a Mac part? I don't see any other markings on it.

Here's an adaptor block that will allow me to run a Tilly HL carb on it. I've not yet decided if I'm going to run an HL or the BDC.

 

[cpr]

Looks good Brad. Wondering if that adapter will make the carb stick up too high to get the cover on though.

 

[Jacob J.]

Looks good Brad. Wondering if that adapter will make the carb stick up too high to get the cover on though.

He's not going to get the cover on anyway. He has to cut the air box area of the tank out for the sloper manifold and the stock mount wouldn't line up.

 

[turtle561]

Fwiw

boysen reeds ?
tuning tip from a kart site :Reed Cage Assembly

The last major development was a method of re- arching the reed guards. Our re-worked guards allowed the reeds to open at only a fraction of the force that it took to open them with the stock guards. The effect was amazing. The engines didn't sound anything like anyone else's as they had a deeper, throaty sound and they made so much more power we ended up all the way back to the 4 to 1 gear ratio everyone was running except we were still at 12,900 while the competition was at 11,200. The real neat thing about it was that the engines became ultra reliable once we sorted them out and I didn't have to run them lean or hot to get the power.

 

[cpr]

I realize the box has to be cut. By alignment I assume you mean no bolt mount on the carb to receive the cover?

 

[blsnelling]

boysen reeds ?
tuning tip from a kart site :Reed Cage Assembly

The last major development was a method of re- arching the reed guards. Our re-worked guards allowed the reeds to open at only a fraction of the force that it took to open them with the stock guards. The effect was amazing. The engines didn't sound anything like anyone else's as they had a deeper, throaty sound and they made so much more power we ended up all the way back to the 4 to 1 gear ratio everyone was running except we were still at 12,900 while the competition was at 11,200. The real neat thing about it was that the engines became ultra reliable once we sorted them out and I didn't have to run them lean or hot to get the power.

Thanks for the info! I'll definately do that mod to the reed stops. So Boysen reeds or from somewhere else is not recommended?

 

[Busmech]

I think back when that may have been true, but modern reed materials are better. I've run both Mac and Boyeson and can't tell much difference.

 

[Dennis Cahoon]

......V-force Tassinari make a modern version of the old mac 12 petal for pretty much everything now-a-day except for the Mac's. V-force are "kind".

 

[turtle561]

http://www.boyesen.com/-they are good, a current producer of reeds with modern materials and designs for performance cycles, outboards, karts, etc.
vintage karting sites may steer you to a source for vintage mac reeds. i think they were a fabric reinforced phenolic resin. there may be some made of modern stuff that matches the old mac flexibility ?
those old reeds would be 30 years old, so i'd look for some thing new. resins get brittle with age, as they are continually cureing.

http://www.ebay.com/itm/Genuine-McC...493?pt=LH_DefaultDomain_0&hash=item19cb4dd2d5

 

[blsnelling]

Thanks guys! All info here is appreciated. I'm admittedly a newbie at all this and am trying to learn everything I can.

I finally nailed down a muffler.

 

[cpr]

If you have a "b" block you might need the rectangle exhaust gasket to fit in the recess of the block. Was that the one on evilbay this week?

 

[blsnelling]

If you have a "b" block you might need the rectangle exhaust gasket to fit in the recess of the block. Was that the one on evilbay this week?

Yes.

 

[Metals406]

I'm even more newbeeish than Brad with reeds. . . So take my question for my experience -- but is there a reason the reeds can't be made from thin stainless?

 

[cpr]

If a metal reed chips off, it'll trash the engine. The fiber ones won't.

 

[Metals406]

If a metal reed chips off, it'll trash the engine. The fiber ones won't.

How would a guy chip a stainless reed?

 

[Busmech]

Bang it against the reed block a few thousand times a minute, they'll split. Early saws had stainless reeds but they weren't high rpm motors. McCulloch and West Bend and others started building fast motors and switched to the phenolic reeds because they don't do damage when they fail.

 

[Jacob J.]

http://www.boyesen.com/-they are good, a current producer of reeds with modern materials and designs for performance cycles, outboards, karts, etc.
vintage karting sites may steer you to a source for vintage mac reeds. i think they were a fabric reinforced phenolic resin. there may be some made of modern stuff that matches the old mac flexibility ?
those old reeds would be 30 years old, so i'd look for some thing new. resins get brittle with age, as they are continually cureing.

Yeah I agree with passing on NOS Mac reeds unless it's just a shelf queen that you're going to run for short periods every once in a great while.

Some of the kart guys are switching to reinforced Carbon Fiber reeds which I've heard good things about. There's also some modern two-stage Boyesen reeds that fit the Mac cages. One group of the karters got together and had a batch of reeds made custom by Boyesen.