MOPED ARMY

This is my weekend project...

For yer pipe I would imagine you'd see a broader power band with less hit. With the circuit pipe I actually put a bigger header pipe on it when I did the side bleed. So I did see a performance increase but also noticed a broader range of rpm in the powerband.

I welded a nut on the exit for different size mlm Allen bolts for adjustment. For me, the smallest size worked best. The larger sized one did not work very well.

It's kinda goofy in that mine hits twice. It seems like you've topped out then it starts to go again. Probably more of a dead spot really.

So maybe some gurus can chime in on this on, because my post is largely word vomit.

From what i've read in 2t tuning books, a sidebleed pipe at the largest belly section will be considerably quieter because the pulse is at it's widest point in the chamber. For any mass produced pipe, it will not perform better than the converging section to a stinger.

But, depending on where your peak RPM is, you can tune the belly section to resonate at that RPM. That way, you are maximizing the pipe while keeping the noise level to it's minimum.

Even with a side bleed pipe, you have the option to play with the stinger length and I.D., which does play a role in low end/high end power/sound.

This post is from 2004 so is dated. Since then, there has been some improvement in exhaust tech. https://www.prestwich.ndirect.co.uk/tunedpipetheory.htm

take it with a grain of salt i guess (edited)

Probably a milder hit, and reduced over-rev.

Probably should tie the stinger back into the main body, or it's gonna break off.

I did something wrong because the pipe never came on. I might cut the stinger shorter but I’m over it right now (edited)

Simonini has been building 2t motors and pipes for decades, if sidebleeding this pipe increased performance they more than likely would have done so.

the thing that gets me and I think gets alot of others too is just the way the stress distribution is for that baffle, it's pretty easy to rip or just fatigue a sidebleed off. how're y'all reinforcing these to get em to last?

I've built a few center bleeds. One thing I learned is the rear end should come to a point, or close to it. It's better for the return pulse.

Can't tell from the pic but yours looks like you just chopped the end off?

The side stinger plays a big part, much like an end bleed. I've found that centering it in the belly works best. Length and diameter follow the same basic principals as an end bleed stinger. And yeah, gusset that pipe on there. You're attaching it to the thin wall of the belly, and it's gonna want to break off. Especially since you're probably gonna kick it or step on it, depending on where it's mounted.

The end bleed tiny hole trick never worked for me. Or anyone else that I've read about. I made my pipe with a threaded end that I could screw carb jets into, easier than drilling mm holes in a bolt, and I thought, " man, that's a brilliant idea, this is gonna work awesome."

After testing it at the track, it didn't do shit, no matter what jet size I used it just went slower. So I blocked it off and it's much better.

Mine has that 2 step power hit, too. And it's definitely not a dead spot. Hits kinda softly in lower midrange, keeps accelerating, then boom! Hits again at high rpms and keeps blasting.

Definitely quieter, too. My pipe has no silencer, and makes less noise than a muffled pipe.

I'm not claiming I'm the center bleed guru, but I've built a ton of pipes, did a lot of math (mostly using Bell and Jennings formulas) and tuned them off their basic guidelines, making modifications to fit my set-up.

Here's the pipe on my V1 "bicycle." Next race, I'm gonna mess with stinger diameter and see if I can go faster with a smaller diameter and not blow it up.

(And before anyone says "you're header should be longer blah blah blah," it's designed for track use only. I want it to hit hard and it does. The few times I've ridden it on the street, it sucks. It's not designed to cruise around at 35mph.) (edited)

I made it so the baffle was real close to the pipe itself, threw a small piece of metal inbetween and welded em together.

Good to know that others have seen the pipe hit twice.

I was wondering about closing the end bleed off completely but never tried....

Love the Polini space filter without the cover!

It is the only foam filter that works good with a dellorto or mikuni carburetor (any carb really) with the exception of a K&N type mesh filter! why people use double wall uni filters and other junk foam and other totally ridiculous and or restrictive filters I will never understand! It’s k&n, large mesh or Polini space filter or none,

I’ve used more open red foam filter material in the space filter also and gained 1 jet size too,

The Polini space filter will not get saturated with gas, water or anything condensation as well as ice, snow rain for any length of time,

I’ve just rode recently with a friend of mine who had a tomos with the double foam uni filter and the moisture on it froze @30 degrees when sun set on a mid 40s degree day after we were parked for a few hrs,

It was like him running with his choke on so we had to yank the filter and then he ran lean and stalled a few times, first time he locked so he probably soft seized, what a joke!

Just seeing that filter means I know you know what you’re doing :)

Yo guys put silencers on those pipes your going to get us in trouble.

Dirty Dillion be like yea guys!

Rocco Taco be like "modded my pipe, now it's worse!"

I really didn’t know what else to expect! All my mods go down hill! Lol

I might try redoing it, y’all blowing up this post. i welded it flush. The motor was chocking on exhaust fumes, I made the stinger to long and exhaust fumes are building up to much pressure in the expansion chamber.

I could open the end bleed but it’s so fucking loud.