Buller KB-Y97?

[arc100]

Those are pretty wild numbers, you’re right about that. I’m surprised you can run that low a clutch stall RPM.
Tell me about the pipe you now have. Header length from the piston to the first cone and the total length of the pipe.
I don’t have my old numbers for pipe lengths but I’ll tell you, my Number 1, for opens, was a lot shorter than the stock Mc91 pipe.
You might research Dr. Blair’s 2 cycle pipe theories. Belfast University. That’s where I got my numbers for my first pipes. His numbers for total length and header length are real close. I improved my pipes with changes in diameter and shape, but the lengths stayed the same.
One thing important is where the engine reaches peak torque.

Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.

Which numbers are you refering to? My port numbers or the clutch stall numbers that townglider uses?

Probably should be running closer to 11800 but havent been game to venture that far outside the spec of the clutch adjustment.

I use 11,200 clutch stall on my modified jica with the numbers i posted.

 

[alvin l nunley]

Which numbers are you refering to? My port numbers or the clutch stall numbers that townglider uses?

Both the exhaust and blow down. And it makes a difference how much you widen them. Area/time is the important thing. The area of the port and the time, in degrees, it's open.
I can see that clutch stall, but I would want to see the RPM, from the dyno runs, where the engine reaches peak torque.
With that kind of power, it may be hard to get it to the ground. Maybe a low stall RPM would help that.

 

[azrcr]

Getting the pipe the correct total length, is probably the most important issue, the pipe building formula will get you real close., the cone dia. and angles are important as well to get it to run with your port timing numbers and the target rpm.. I've got about 10-15 old pipes I use to cut up for the cones.. saves alot of time when building pipes..

The first 250 pipe I built, actually performed a bit out of the range I was looking for, not a bad result, I got a few thousand more rpms, than I was expecting, (alot of overrun)., but didn't pull off the bottom as expected, so be ready for what it does.. I have a 2nd pipe, hopefully will be a better low/mid than my first one..

 

[jack burroughs]

Yes, I did run a KB-06 on a KT-100, stock engine with a Tilly 360-C alky carb, in bracket enduro class at Roebling Road, really used the alky, but just about flew.