The Kart Engine Thread

[cpr]

Great stuff guys, keep it coming! This is what I had in mind.

 

[Bill G]

Here I will try the pics again

 

[Tzed250]

Bill, that engine is beautiful!


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[Bill G]

Bill, that engine is beautiful!


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Both the KB7 and the DA211 engines belong to couple longtime kart racers on the west coast. A few years ago I sold them some spare Mercury-Disston engines I had. I wish I had the talent to do what they did .

Bill

 

[Jacob J.]

Bill, that engine is beautiful!


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I believe that's the engine that Will Rogers built, but Jack Canady was the first to build one of those years ago. Both are long time kart guys and good machinists/mechanics Jack has been experimenting with hybrid kart engines for a long, long time.

 

[Bill G]

JJ,

Will and Louie

 

[Jacob J.]

JJ,

Will and Louie

Oh gotcha. I talked to Jack years ago about building one of these, around '98 and '99. I traded him some PP parts at that time. I had two running, mounted 58 engines converted from an Air compressor and a water pump.

 

[wigglesworth]

two running, mounted 58 engines...

I got one of them. Well, it fires on a prime. I havent done anything else with it.

 

[rwoods]

No, higher RPM doesn't translate necessarily into higher HP automatically. I actually prefer in many cases, the saw blocks, especially in larger displacement. My latest project involves cutting the heads off of three SP-125 blocks, having them bored out .050" over and chromed, and then fitting custom heads to them. Two will get all-new manufactured heads while the third will get a custom WB-820 head that has larger cooling fins.

One of the biggest complaints I heard from guys (including my dad and grandpa) who ran the kartsaws in the woods was the high temps they ran at. After I tore down all my dad's saws I could easily see what he was referring to. There was a lot of really baked-on stuff that had seen high temps.

Hopefully we can get Lee involved in this thread as well, since he's built up some of the kartsaws. Jay (Bigbore577) and Hoss both have 101b kartsaw rigs.

Another of my kooky ideas involves a Homelite 990 saw chassis, an Mc-7 crank, an Mc-90 .010" over domed piston (thin rings), an Mc-93 rod, and a Mikuni 34mm carb. It's a witches' brew but might make a good runner.

I assume the elder Js ran kartsaws because they cut faster. If so, is this due to more overall power or a change in the power curve to higher rpms? Just how many rpms does a logging MAC kartsaw turn? Ron

 

[sawbones]

some homey stuff

 

[cpr]

Holy smokes, the John Deere G flywheel of the 2 stroke world...

 

[Brian13]

I had read in a older thread, that in order to take full advantage of a kart engine it would require heavy modification to the intake. How does a kart engine effect the saw with a standard saw intake and carb. I have been wanting to build another Super 250, but with a Mc-92 in it but not a hot saw. Using that for example, running a Super 250, and one with the kart engine with standard saw intake, what differences can you expect? Higher RPMs with a little less torque, all around more torque and RPMs, or something else? I know its kind of hard to quantify, but learning how the porting effects the performance is of interest to me.

 

[Jacob J.]

I assume the elder Js ran kartsaws because they cut faster. If so, is this due to more overall power or a change in the power curve to higher rpms? Just how many rpms does a logging MAC kartsaw turn? Ron

Change in the power curve for sure. The kart engines do make more overall power in any configuration. It does help to use different intakes, carburetion, exhausts (in some cases.) If you're going to run a kart in a saw though, you'd want to find one with stock or almost stock ports. A lot of kart engines have had the exhaust port molested and that really hurts the torque levels of the engine.

 

[ttyR2]

I remember reading this book that I borrowed from the library over and over and over again. Had a lot of info about modifications (circa 1961).

Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs & more

 

[Jacob J.]

I had read in a older thread, that in order to take full advantage of a kart engine it would require heavy modification to the intake. How does a kart engine effect the saw with a standard saw intake and carb. I have been wanting to build another Super 250, but with a Mc-92 in it but not a hot saw. Using that for example, running a Super 250, and one with the kart engine with standard saw intake, what differences can you expect? Higher RPMs with a little less torque, all around more torque and RPMs, or something else? I know its kind of hard to quantify, but learning how the porting effects the performance is of interest to me.

What you'll get is an engine that makes its power at a different RPM range. Yes, opening up intake and using a custom reed cage, manifold, and larger carb gets you more power but that's true on any 2-cycle engine. Higher RPM, more overall power, but it's a different torque band. You get a lot more heat with the higher compression of the kart motor as well.

 

[cpr]

Seems most, if not all, of the 101 powered saws I have seen include a decomp valve that was never a part of the original engine. Was a head swap performed, or were they added as part of the dealer-installed option? Is there a boss cast in where one can be placed?

 

[Jacob J.]

You have to grind a spot in the head for a de-comp. There's not really a boss per se', but a cast area in the head that has more material where one can be installed. I've drop-started ones without it and it's miserable. Even with one installed with the timing stock can rip the handle right out of your fingers. It's no wonder a lot of the old-timers have carpal tunnel problems.

 

[cpr]

I hear that. Never even bothered to try drop starting ANY of my Macs, especially after one of them caught, ripped the handle from my right hand and bloodied my left thumb on it's way back to the housing at 200mph...

 

[Busmech]

I have 4 broken d handles from starting my 101AA hot saw (no decomp).

 

[Saw Dr.]

That is the first one of those engines I have ever seen that NEEDED the airbox lid turned backwards. The Ebay clowns are all trying to get ram-air on their saws, and the cart racers forgot to.....

Hey, that reminds me: Anyone know the maximum RPM of the hundred and first kartsaw points electronic racing MAC????

:angry2::angry2::angry2: