NA or SC ... is it that simple ?

[oab_au]

Hi Sonny, yes that was Walter Kaaden.

The first sign of it, appeared on the 350cc 3cyl Jawa. before it was to become the MZ group. Kaaden and his rider, Ernest Degner worked together to develope the 125cc GP bike that was invincable. Using rotary disc valve inlet and the full expansion chamber system, that has not changed since. Look at the Aprilla, it is still the same.

Unfortunatly MZ did not have the money for the exotic metals that would make it last. So Degner absconded with a bike to Japan, to give the secrets to Suzuki. I raced a Bridgestone 350 twin, rotary disc valve, built the chambers for it, but the coupling between the two cylinders, had a fault and broke, often.

I remember the DKW, looked like a three cyl, except the center one was the pumper, no expansion chambers, just straight pipes, terrifing noise.

Yes the chamber uses both wave pressure and back pressure to do the job. As the exhaust opens, the positive pressure wave travels down the diverging cone, it starts to expand, to return a negitive pressure wave to the cylinder, down the transfer ports and into the crankcase, to fill the cylinder and header pipe. The positive pulse continuies on, till it reaches the converging cone at the back of the chamber. This appears as a closed pipe, so it returnes a positive pressure wave back to the exhaust port. At the same time the body of the chamber is filling with the expanding gas, to cause a rise in gas pressure, that builds up to force the fresh charge back into the cylinder. The exhaust port closes and the gas pressure in the chamber bleeds down out the small tail pipe.

Incedently this is why they have such a loud exhaust sound, as the tail pipe opening is located at the center, of the converging cone, where the sound wave is intensifed, by the cones compression.

I have allways found the two stroke development to be more intersting than four strokes. Though you can carry some of the technology over to four strokes. Tuned inlet and exhaust pipes and expansion/ resonator chambers.

Harvey

[Sonar]

Hi Harvey!

How very pleased I am to meet fellow 2-stroker fan's here ...
And you seem to have had VERY fun with thoose bikes


And I totally agree with you, tuning 2-strokers IS fun

However, I noticed a HUGE difference in reading YOUR post than reading MINE ... I'm not very good at all to describe things in english

One thing I have to discuss with you is this new "thing" I am to build, a super quick pressure sensor wich is hooked to a oscilloscope, then I can (I think) actually see the pulses in a inlet chamber, the freq. and amplitude

I could use this to test diff. volumes and so on, to try tuning the intake system on any engine ... so it gives maximum pulse amplitudes in desired range

What do you think?



/Sonny

[Sonar]

I mean, think about it, the WHOLE engine is built up with parts ans systems that resonates at certain RPM's, even the CRANKSHAFT resonates! , I don't know the english term for this, but it a sort of torsional oscillation (which brakes crankshafts!), and every motor engineer is trying to avoid that particular RPM of the crank.

I think that many of the behaivours of diffrent motors can be traced down to these oscillations of things, you know what I mean if you listen to a motor while it slowly increases the RPM, suddenly you can hear the engine "sing" so sweet in certain RPM's.

Imagine if these oscillation of gases between valves and inlets and pistons and so on, work AGAINST eachother in some RPM's, makeing the engine go rough, and then, BANG, suddely the RPM is just right, and the whole lot is in harmony, and the motor runs sweet.......

-just a thougth



/Sonny