expansion chamber exhausts

[jk50]

I know they boost power in the tuned range. Do they also reduce power when not in the power band? like, will the scooter actually have less power than stock at lower RPM's?

[az_slynch]

Can an expansion chamber reduce base power? Yes.

The trick is to pair the pipe with the kit's port timings and to tune your clutch to slip until you hit the powerband.

My buddy rides an '05 bugeye Zuma and it'll do alright all day with him aboard (big fella). Kit is an Athena Race (the old Stage6 Pro Sport), crank is a Stage 6 LPC, carb is a 21mm Arreche, Reeds are Moto Tassanari VForce 3 and the pipe is a Yasuni R. Clutch takes up at 5500RPM and the pipe's power curve runs from 6K to 10.5K. Rear end gears are 10.58:1 and it pulls like a healthy 150cc with him aboard.

Another friend's Buddy 50 (another big fella) has a 21mm Arreche, a Stage 6 Sport Pro MK.II, Stage 6 HPC crank, Malossi medium reeds and a Yasuni C10. Polini DIo CVT setup with an RRGS rear sheave. Polini 9.9:1 rear gears. It's a bullet off of traffic lights and runs 62-63 with him aboard.

I need to find smaller friends so I can lengthen the final gearing and see how fast these can actually go. I did recently run against the Zuma with a 280lb friend aboard. Dang thing totally smoked my lightly tuned St. Tropez off the line and walked away!

[jk50]

I’m guessing I should just stick with the sport exhaust I have now. I already feel it is revving way higher than I would like for just cruising around at 30-35mph. maybe I’ll get a NCY pipe at some point just to try.

[az_slynch]

I have a spare MLM sidebleed pipe for a Buddy that you're welcome to. That scoot only ran it for a few days before getting upgraded to something more suitable for a big bore.

I've got more than one and wouldn't mind passing this along if it gets put to good use.

[jk50]

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