Mac extra porting !!!

[Gordon Duax]

Again,
Mute point !
He's got the record.........

I told him it wouldn't work, it was a bad idea, that superchargers don't work on 2-strokes, etc., etc..

But it did !
Is it efficient ?
Probably not.

Are we going to see a comeback of 2-stroke bikes, with blowers on them ?
I doubt it.

But then again, 2-strokes in general are going the way of the dinosaurs.......

[mcbob]

Gordon does that mean we heading for extinction as well ??????????

xxxx man i better start running now ...............

Mc Bob.

[jmendoza]

I know of a supercharged 2-cycle engine by Jim Nightengale that was a prototype. It used a poppet valve in the middle of the piston dome that was opened and closed by pressure, and the cylinder had 360 degrees of webbed exhaust ports at the bottom, they were fairly low and only occupied less than 30% of the stroke. Another version used a counter piston as a pump instead of a rotary vane type blower. Both ran well, but were impractical to produce due to size and complexity on a small scale.

This design is similar to the early Gnome Rotary engines used at the beginning of the last century for aircraft before, and during WW1. The only differance is Jim's engine used a pump to boost the pressure. Once the exhaust closes, the pump can continue to boost cylinder pressure until the clylinder pressure builds due to compression and forces the poppet valve closed.

The Gnome was later improved with a single poppet intake valve in the head, and exhaust ports, this was called a monosoupape, or single valve, as the poppet valve in the piston dome tended to leak or hang up causing a crankcase fire and the subsequent firery demise of the plane and it's pilot!

[REAR]

Great thread guys.

Gordon, if fuel delivery ever becomes a problem maybe your friend could look into a 'pump-a-round' fuel system like many long track modern shifter kart guys use.

I am not very well versed in them but I think they kind of resemble a fuel injection fuel routing pattern where there is a over abundance of fuel at the needle but what ever is not used is routed back to the fuel tank via a return line so there is never a shortage of available fuel ready and waiting to fill the bowl. Again I'm only relaying what I have been told.

Thanks for sharing this supercharger info.

R.E.A.R.

[Gordon Duax]

Man, did this thread get highjacked, or what....
Sorry McBob !

After reading through some of the e-mails from the bike guy,
I think his problem was that he was blowing through the carb with the blower.
I don't think he sucked it dry, I think he just blew all the fuel back up to the tank.
When he pressurized the tank, then fuel would flow back down.

This would not happen if the blower sucked through the carb.......
Besides, pressurized fuel systems were outlawed on karts many moons ago...

Bob, Did you notice I put 'Hot Saw' in the subtitle of my auction for that blower ?
If it says that on eBay, it has to work, right?

Like your cut-up block Bob.
That is one thing I always wanted to try with the 820,
1 in front, and 1 in back.
Is that a 'Double Mac, with cheese" ?
No, that would be your dual engine saw.
Maybe it's a Biggie Sized.....
No, that's Wendy's.

[mcbob]

I think you been eating toooo many Big Macs and fryed the old brain cells Gordon

PS Maybe Mac's ideas on the Balanced Piston engine i have a BP-1 Chainsaw 10,000 RPM AT 40cc in 1962 not bad not bad at all it used two pistons with the second piston pumping the fresh charge. MAC TECHNOLOGY WAS LIGHT YEARS AHEAD ................................

McBob.

http://macbobaust.com/saws73.html

http://macbobaust.com/bp1bits.html

[Gordon Duax]

You got that right Bob.
Back in the early '60s, when Yamaha first brought 250cc GP bikes to Daytona, they got their butts kicked by the 4-strokes of the day.
Supposedly, some of the Yamaha engineers took time to watch that new motorsport called karting.
They were so impressed with the performance of the Macs, they bought a couple, and hauled them back to Japan.
The next year, they came back with all new 250s, that run the butts off the 4-strokes for the first time.
That was the nail in the coffin of many of the Euro 4-stroke bikes.
Much of the early 2-stroke SAE papers were submited by McCulloch engineers.
They wrote the book on high performance 2-strokes.

[Tom Smith]

What the stupid little kart motors need are better exhaust ports, not more intakes. they have plenty of intake area. The Super Pro 125 exhaust port is a good start.
A hot rod 101 saw will turn 17,000 rpm, how much more do you need?

[mcbob]

I remember i'm sure Steve O'hara saying the same thing when i asked about porting ,,,,
I see that the exhaust port on both the 101D and the SP125 changed in shape with both of them having what appears to be a curved top radius on the exhaust port opening ..... the SP125 i have i'm going to add a set of ears to to increase the exhaust port area and build a larger header flange and pipe.

Mc Bob.

[Tom Smith]

McBob, check out Gilera Grand Prix Racing Bikes from the 30s and then tell us how Mcculloch was light years behind the times.
Here are a couple more great copy jobs, Chrysler Hemi head and valve train is almost identical to a Talbot Lago race car.
Miller/Offenhauser, Ferarri, Cosworth, Honda, Diamler, Alison, Roll Royce etc. and all the other dual overhead 4 valve engines ever built are copied from a 1916 Peugot race car.