My AX100 Powerband

Because this bike only has a 4 speed gearbox I had to make an extra long
baffle to give the needed long pipe powerband to cover the RPM gear spread
but what I was left with was having to completely wind it out each time
before shifting in order to keep it in the pipe powerband which turned out
to be a big hassle for using it on the street. So I changed the pipe to have
a really long belly so the pipe powerband was without the baffle wave.
This sounds crazy but it worked like a lucky charm. The bike originally
had that design but I didn't understand how it worked so I cut it off to try
my own designs of expansion chamber. Live and learn.

When looking at these combined waves graphs keep in mind that as RPM increases the timing markers (BDC, TC, EC) move to the left. That is because the wave return times basically stay the same but the engine cycle times decrease as RPM increases.

Beginning of baffle boost at 4400 RPM.
It is just beginning to have pressure at exhaust closing.
Unfortunately it is offset by the lack of intake boost due to no diffuser wave
between BDC and transfers closing. This lack causes bare minimum intake.


End of baffle boost at 5200 RPM.
Pressure starts at .5ms before the end of exhaust closing.
(some time is needed to push air/fuel mixture back into the cylinder)
Since at 5200 there is neither baffle boost or diffuser boost then this is the
beginning of a power dip that I had to offset with a boost bottle. If I
shorten the belly so that the end of the baffle boost happens at the same
RPM of the beginning of the diffuser boost then I may not even need a boost bottle.


Beginning of diffuser boost at 5850 RPM.
Diffuser wave exists for 1/2 of the time from BDC to transfers closing.
This is the minimum needed for increased intake.


End of diffuser boost at 9,350 RPM. Past this RPM the diffuser wave
will start to be significant at exhaust closing which would cause
excess loss of air/fuel mixture from the cylinder out the exhaust port.


This is what it should look like at 5850 RPM with the belly shortened
from 440 to 390mm. This is ideal because the end of the baffle
boost happens just as the diffuser boost starts. This setup gives
the longest powerband possible although the peak power is a little less.



PS- This is the normal way of learning, by trying different things
and then learning from the results. People have actually criticized me
because I've made mistakes along the way. ha! I tell them that making
mistakes is part of the learning process, just like falling
occassionally when learning motocross. I don't hate that I've made
mistakes and gotten mud on my face. It's necessary. I wouldn't
be who I am without my mistakes. The only thing to be ashamed of
is not learning from mistakes.