Richard wrote:

Made a first test run with P-Port only. The side port was closed

off

at the side housing.

Fired up immediately. Idles at 1200RPM. No close up butterfly.

Intake

control is with carb slide only (38mm Mikuni).

Intake length is 6.5" and is not supposed to be tuned any at this
time.

Exhaust is equipped with tangential muffler with no buffles inside.
Can be tolerated in the test stand without ear protection.

I am pretty sure that this is the end of the combination port
configuration, as far as I am concerned. With 1200RPM idle and
7500RPM max, I have a RPM ratio of 6.25/1 giving a comparable LYC
idle
speed of 432RPM, I can't ask for any better.

Richard, please remind me what the problem was with the combo port?
Have you compared power output of the two?

Hans

 The combo port idea was solely born by the high idle concern with the

P-Port. Therefore, it is more a matter of "not needed" than a problem. I
have not done any high power runs yet, mainly because the engine is not
fully balanced at this time.
I have observed a cross influence on the two ports at higher power levels
(3500RPM) which seems to indicate the need of identical closing timing of
the two ports.
I am trying to avoid this issue at this time because of the main goal of
having a light weight, relaiably running engine.

Richard Sohn
N-2071U
unicorn@gdsys.net

If you are making your own aluminum end housing, as Richard is doing essentially,
P-ports simplify the problem greatly.


Paul Lamar
 
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