RE: little toni
I think speed, real speed automatically means two stroke. Why go through all the extra work of running a valve train or a supercharger?
Having it go bang everytime around just seems to make more sense doesn't it? Plus you lose all the dead weight a valvetrain brings with it.
I own a couple YS engines and I love em to death, but anything meant for speed ( Jett60 powered 50" sundowner, Moki210 powered 80" sundowner, and my Zenoah 80CC USRA GS 42% Kelly F1) uses a two cycle engine.
I'm not a smart guy but it sure seems that's what smart guys do when they want a plane to haul the mail.
JMHO