KTy

Alloha ! ;) I am working on smallframe casing to fit a Polini 133, and I'm just wondering if you guys use some formulas or "common knowledge" for the size of the admission. I'm going to fit a big motocross reed valve membran (Gerhard did I think), but I am wondering if I should try to maximize the output surface or if I should weld some sort of a venturi inside the casing. Here is a picture that will explain better (maybe) :) So is there a "perfect" ration c/b ? And will a venturi be usefull ? Thanks guys ;) KTy P.S: Plz reply in english if you can... ;)

Sounds great ! Just to let you know, it seems this pipe have been bought very recently from Zirri in Italy, so they *might* only make this kind of Silent now... Do you recommend a software that would calculate the pipe features ? Like somehing to reverse-engineer from these numbers and give approximate and theoratical powerband and stuff ? @Gerhard : Do you have close pictures of your admission ? Is it part of a modified Malossi reed valve manifold ? I :love: 2 strokes ;) KTy - I wish I could speak german... :(

Here you go, I hope nothing is missing :) Muffler outer diameter is 6cm. http://ktylife.free.fr/vespa/KTy133/zirriDimension.jpg Thanks !! Oh, btw, do we have enough dimension to sort some numbers out of this zirri pipe ? Or do I need to measure those angles ? Cheers, KTy

Hi guys ! Sorry, I don't speak german I'm waking up this old thread because I just received my Zirri Silent from an Italian guy that only used it for 12 days on a stock primi...! What do you think it is ? I thought it was a Corsa, but maybe it's a Silent Pro ! What should I mesure to check it ? Thanks !! :wasntme: KTy