Almost as much HP as a lawnmower: 50cc roadracing

The Something Awful Forums > Discussion > Automotive Insanity > Cycle Asylum > Almost as much HP as a lawnmower: 50cc roadracing

Gay Nudist Dad: Dec 12, 2006; asshole on a scooter

Rev. Dr. Moses P. Lester posted:

Had a drag race today against a Buddy 50 scooter with a Prima pipe. (it's a p. fast scooter if you're not aware, bro) I won. So I'm feeling optimistic.

Bought a copy of this thing http://www.buildandclick.com/html/tuned_pipe.html and ran the numbers on it. It came up with a pipe that seems surprisingly not that aggressive. Meaning the width of the expansion chamber at its widest is not nearly as wide as the Prima pipe on the above mentioned scooter. I thought that was kinda funny. From the reading I've done, it sounded like for peak HP you'd want a diffuser cone with a wide outlet and a baffle cone with a sharp taper. Maybe it depends on port timings which I assume are rather conservative on this bike. But I'm thinking about trying the hydroforming technique on the software's prescribed pipe this winter.

Is the Prima Buddy pipe a true expansion chamber? I know in the Vespa world a lot of "performance pipes" are actually baffled inside. I'm not sure if that holds for the Prima Vespa/Stella pipe (but I do know that pipe is not well-regarded).

# ¿ Sep 7, 2015 05:01

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Gay Nudist Dad: Dec 12, 2006; asshole on a scooter

open24hours posted:

They have these on a lot of street legal scooter exhausts but they're usually extremely easy to remove. I had a look at some of the Vespa pipes and it looks like you have to cut the thing open to get them out?

I don't know anybody that has done that, everyone just goes for a better pipe. There are a lot of true expansion chambers out there for Vespas. We don't have to deal with inspections or anything, though.

# ¿ Sep 7, 2015 22:09

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