MOPED ARMY

Header pipe is also about 3" longer than stock.

And the big patch is where the old mount was. It was cracked there so I grinded off the mount and patched it.

I have an identical stock end bleed circuit, and the side bleed gains 3mph. Not a lot, but every little bit helps when you're racing.

From everything I've read, the center bleed should be at or behind the center of the belly.

I tried having a tiny bleed hole at the end. I welded a bolt with the same threads as carb jets into the end, and tried 2mm and 2.5mm holes, but it worked best plugged completely.

if the header is 3" longer, you aren't going to really gain any more RPMs unless something else was wrong with the pipe prior.

max power rpm is a function of tuned length and exhaust duration. make the pipe longer, it will rev lower.

who knows tho?

So, yeah, totally works.

Still has a lot of low end power to blast it off the line, and you can feel it kick in hard at about 7k.

But instead of a short burst, it keeps accelerating, and you can feel another kick just above 9k, where the stock proma punch is over with.

Quick run around the neighborhood hit 52mph at 9875 rpm on my race bike. It's got a little more, but my racer with no suspension is a handful on bumpy streets with cars around, so I didn't push it to it's limit.

The goal was to make a better short track pipe. The Apex kart track has a 650' straight, and the stock proma hits its peak at about 500'. I wanted a pipe specifically for that track, that still rips in and out of the tight corners.

And it worked!

The Grange track (which is now AVS, Apple Valley Speedway,) has a 950' straight, and a lot of races are won in the straight, which kinda sucks, because you can rip all over someone in the corners, and then they can catch up (or pass you) in the straight, and then you have to fight all over again to get ahead.

But I have a pipe for that, too...

Feckin wild! I haven't really messed with promas much just because of the hard shut down, but very cool that you're pushing the limits.

Those are some crazy looking pipes!

The other pipe is a metragas derby hacker whatever pipe with a header from some unknown pipe welded in. Hits hard in mid-range and carries the powerband up to max rpms. And centerbleeded it, which cut the noise down by half. Weird how that works. https://www.treatland.tv/ProductDetails.asp?ProductCode=derbi-metrakit-giant-muffler

The circuit header parts were the almost 90° section of the above metragas pipe, with a coupla pie cuts to bend it some more, and the last header part is off of some extra pipe I had laying around, maybe from a Sachs? The bends fit almost perfect.

The little converging pipe piece is from a 1" seat post where it tapers smaller to fit a seat clamp. And I cut my own flanges.

The stingers are just some pipe I got from the metal store. I forget the exact diameter.

The circuit is actually upside down, which puts the bleed pipe right under the engine, and exits under my foot. Hopefully it doesn't soak my shoe in oil, cuz I don't want to do a slippy slide getting off my bike. But I think it's pointed down enough... (edited)

I keep telling you too. Probably be the perfect pipe for a heavy bike. And they're only $100 bucks at treats.

I may take you up on that. I need to sell a pipe. I got an mlm people pipe I think?

So I sold my mlm pipe and got a circuit. I had a mamba circuit years ago and realy like the low power but the tin sound I wasn't super excited about. I'm sure this will be the same but the trike will surely like it. I got the v1ks running after a bit of fuss and put on a polini I had. I may mod my pipe to side bleed like this but I may just leave it alone as I'm not looking for major performance on the trike, haha