Modern Vespa

Highly doubtful. No European part was / is developed with a US market Vespa in mind…

okay... I'll go thru each one.

forget about this one: https://www.mdmmarri.shop/negozio/?store-page=marmitta-espansione-payper-k2-EVO-special-prim-et3-corsa-lunga-p593850135 it's obviously for a PK so none of that works. also PK's sit way higher than non PK smallies, so you'd be dragging that pipe all around the street.

this one is the same: https://www.mdmmarri.shop/negozio/?store-page=Marmitta-espansione-vespa-payper-k2rr-p596573406 no dice here. you'd be cutting the back 1/3 of your battery box and probably well up into the body on that.

again more of the same here: https://www.mdmmarri.shop/negozio/?store-page=marmitta-espansione-payper-k3-p593850148 you'll notice that they've fully hacked off most of the body work. this is the worst of the bunch, total nonstarter.

this last one is interesting: https://www.mdmmarri.shop/negozio/?store-page=marmitta-espansione-Revolution-2023-Et3-primavera-p596564702 it looks like it might mayhaps just-t-t-t clear the rear of the battery tray and skirt on the bottom of it. but it's hard to tell from the picture. the likelihood is that it's a no-go as well.

an interesting pipe as it shows modern pipe design elements, but I think the header is too small and it clearly never met a left turn. reminds me of the old zirri circuit pipe... iykyk

You maybe mean this one Revolution 2023 ET3

yes. correct. thanks for the heads up, I went back and edited the link.

For the Payper K2 and K3, he makes a version for the PK and ET3, the K3 however appears to begin expanding right at the curve before going into the chamber, as in it'll start to get thicker right as it begins to curve around the battery box, the K2 is not as bad if you look at both pictures side by side. I think the main reason for the cut up body is just to show the fitment, it seems just like a salvage scooter anyways.

What about the electric start models that use the same battery box like the 50 Special Elestart? I think those are European only models.

Very small numbers and at certain European countries that required battery for horn, turn signals, etc.

look, I'm not trying to be rude or condescending so apologies if it comes off that way, but have you gone out and looked at your bike? like got up under it, pulled off the side panel and inspected the architecture?

both of those pipes have a fat lead divergent loop down *right* where the back rear of the box would be. to my eyes, there's no way the K3 fits. the K2 gets a "maybe" but I'm going to guess that it comes out too far horizontally toward the panel and bumps the panel and if not you'd be cutting a big chonk out of the box for the loop in the back.

both pipes are suspiciously close to the floorboard, too.

if you nose around on forums and search images you'll notice a common theme amongst the big power smallies: they're almost all European bikes-- so no battery boxes, and almost all to a T have modified bodywork in some way: clipped floor boards, cut inner structures for headers, gacked out side bubbles for carbs.

100 Sport in original excellent condition? Doesn't that have a 3 speed trans or is that just 90s? As long as you gotta save up $$$ for the ferocious motor build of your dreams how about this? Save up enuff for a new set of cases too and put the original motor on the shelf. Here's a better case than you have now for ~ 500 and you're gonna have a LOT more than that in all the other parts you want, so more blow up proof could be cheap insurance.
https://www.sip-scootershop.com/en/product/crankcase-sip-evo-for-56mm-stroke-crankshaft-for-vespa-50-125-pv-et3-pk50-125-s-1_24311B00

Not at all, but thanks for at least saying that since as you know it can be hard through text, but yes I have looked at it. The battery box isn't too wide, and based on those MDM pipes, they look to go all the way back to the rear fender and begin to curve right behind where the back of battery box is.

It's hard to put it in words, but you probably understand what I'm trying to say. I definitely agree in regards to the K3 vs the K2, but I just thought about linking the K3 anyways. I can reach out to MDM if he has an email and ask. I'm still waiting to hear back from JL and Dexter.

It's in great shape, and I'm going to avoid any cutting of the battery box, which is why I'm on the hunt for a pipe that'll fit.

It is a 3 speed and I will convert it to 4 speed, and I was planning on using the original cases to save money, and building the engine around there, which currently for all the parts I have compiled thus far, will be about $2200, I believe that includes shipping as well, so not too bad.

If I were to get new cases and the additional parts, I really feel like I wouldn't need to have the current engine just laying around, and likely will never use after having an engine that rips put in it. So I feel better off just using the current cases and the parts in the engine that can be reused for a performance build, and then likely keep or sell the original cylinder, piston, crank, primary/clutch, ignition, exhaust box, etc.

I get you. I'm just saying that there is a surprising lack of space in there. it's a deceivingly small area and there is nearly nothing that will fit without modification.

and never, ever take pipe manufacturer's word on fitment. their idea of "suitable" for a model is some wildly made up metric. I'd trust JL because I've run their pipes. and maybe dexter.

it's always a good idea to have a spare motor if you have one that's tuned in the bike. that way you have something to ride while you repair the HP motor.

But you are making a good case for just going ahead and cutting the battery box to fit the muff of your choice. It's only a big factor if you resell to a SERIOUS collector who would likely also be interested in an unmolested original motor in it. That'd be a rare case though, these models are not THAT precious or popular. You need the best pipe for the money to make the power you need, not just fit oddball USA bikes.

Depending on the pipe you wouldn't need to hack the whole battery box out. I had a Primavera125 that I put a simpler Simonini pipe on and most of the problem was at the back corner. I think maybe you could lop off only what's needed and weld in a patch, and still leave room for a tool pouch. You want to do a battery delete anyway, but that's better because KISS.

https://www.youtube.com/shorts/gkexRHGYXDM?feature=share

I really suggest you to drop the frame preservation mentality. You will eventually cut into it once you have a three grand lump on your hands that just doesn't fit right without chopping something off

Skip the part where you are making compromises to your goal for trying to make things fit into a frame that was designed to accomodate a 19mm carb and expansionless exhaust.

This way you can design the whole package from ground up without arbitrary limitations and reach your goal with minimum amount of expensive detours.

The battery box looks like it can just come right off, as it seems like its held in by those rubber "nubs" if you will, but then that begs the question, where to mount the battery, rectifier, and indicator flasher.

I know they make those small 12V batteries that are like Lithium and very light, but I don't know what exactly the battery powers. It seems like it powers the horn, brake light, and turn signals when the scooter is both running and off, but how would you get all of that to run off just the stator when the scooter is running?

It will have a S.I.P. Vape ignition, but now if the battery is deleted, I assume just the regular AC version can work, but then I would need to figure out how to wire the turn signals and brake light to the ignition.

Right, but it's a matter of how to power the brake light, turn signals, and horn off of the ignition rather then the battery.

I'll do some measurements, and I'll message the manufactures that make pipes that appear that they will fit and what the dimensions of them are.

I feel like those MDM Marri Pipes like the Payper K2 look like it can work since they go all the way back to the rear fender before curling around. I would think if anything, the very edge of the battery box where there is dead space will have to be bent a little with a hammer.

In regards to the JL VSP road, what exactly is different then the one that GeekLion had on his? The size of the chamber? Obviously the bigger the chamber, the more power. Will that pipe not deliver the power I am going after or something?

But it most definitely has a bigger chamber then any of those small Polini's, Malossi, or Simonini.

Finyoshi has a point... I personally dont like the idea of chopping up that pristine 100sport, but to achieve your goal of 20-30 HP with a fully tuned engine; it will be dammed near impossible not to cut something. Either to fit a pipe, and very likely to fit a larger carb the opening under the tank will need to be enlarged as well. Its very difficult to build a high HP engine in a smallframe without doing this.

Something to keep in mind while thinking about expansion chambers: they are rigidly mounted to the engine, which is also your rear swingarm; so the whole assembly pivots. Just because a pipe clears when mounting, doesnt mean it will clear when the suspension compresses and the engine moves around. The engine is also mounted on rubber bushings, so there is some play there too. All in all, its very difficult to fit a big ole pipe into a battery tray model smallframe.

From my experience, and based on all the different pipes that have been posted in this thread; I dont believe any of them will fit at all without chopping your frame. *Save for the one that I posted, which has the best chance IMHO* Either way, if you want BIG HP, you need a BIG pipe; there is no way around it. And big pipe = chop chop. Maybe a little chop, maybe a full on Ginsue-Knife-karate-kid-chainsaw-man action.

If you are willing to compromise on the absolute top number HP, then you'll be able to fit something that (hopefully) wont require frame mods. You'd be surprised at how much fun a smallie is, regardless of the Dyno numbers!
If building the most badazz wheelie rippin smallie is your goal, sharpen your knives.

The VSP road is a larger diameter pipe that the JL I posted. It would be better for a fully tuned High HP build. It would be a good choice for more max power of the smaller/earlier version I posted. If you go with the VSP road, it will produce more power; and it will require cutting of some sort. I would not plan on NOT cutting .

If it is a priority to not do any cutting at all, you'll have to reevaluate your engine build, and go for something more moderate; but still FUN!!

If your priority is highly tuned and super fast, hit up harbor fright and stock up on grinder wheels, and forget saving that frame at all.

fire up the air body saw and hammers! we got work to do!

So basically, if I chose the VSP Road, I will get the power I want, but I still have to do something with the battery box?

Based on pictures, and like you said, it's identical to the JL pipe that was on yours that didn't require cutting, and the pictures look like it will clear the battery box. I do find it odd however they have a road and race pipe, with the chambers looking identical in size, albeit the race being a curly pipe.

I really don't want to cut it up, but if it requires a little hammering to dent the back side of the battery box in for clearance of the pipe, that isn't as bad.

I see that we are now ganging up on you, and I too really HATE doing things to the frame that cannot be reversed w/ a little welding . But in this case it does seem your best course w/ little real downside. Not that hard to do, most smallies came w/ no battery. Of six smallies that have passed thru my hands, only the Primavera came w/ a battery but I converted it to batteryless. If you had to, you could run turns etc off a much smaller lithium battery you could likely still fit in there, or under gas tank worst case.

But if you do find a suitable pipe that makes huge power w/ no cutting and doesn't break the bank ...

Thanks 👍 we're all here to learn!

Battery box is spot welded into the frame, unfortunately you can't just take it off.

Regarding how to wire it up, I'd find a diagram for a PK 50 or 125 and copy that - they run all that stuff w/ no battery, and your Vape ignition should know how to cooperate.

I think your 100 Sport is already 12V?

Yes, that about sums it up. I dont think they are identical at all. More like they share the same basic form, but what I can tell from photos, the VSP road looks to be larger in diameter than the (lets call it) "early" JL pipe. Also the exact dimensions are also impossible to tell from photos, and a few millimeters one way or another could be make or break when it comes to fitment. Just eyeballing and spitballing, I'd guess that the VSP will still require some mods to the battery box to fit.

It's honestly very hard to tell from photos, but I'd be prepared. Other factors like your particular cylinder height, suspension, and more; will also contribute to how the puzzle goes together. Details aside, none of this will be plug and play; and speculating here on exactly what will fit is difficult and subjective.


In regards to road vs race pipe, its simply a matter of tuning. The exact diameter and length of the expansion portion, combined with the lenght and angle of the diverging cone at the end; both make a difference to where the power band peaks and performs best. I'd also think that the curly version is better suited for race on a track, as its higher and will provide better ground clearance compared to the lower road version.

Your 100 Sport is already 12v. Currently the battery runs the brake/tail light, horn, turn signals. If you go AC only for ignition & power, it will be an easy rewire job. You could also use a tiny lithium-ion battery, if you decide to go AC/DC. Or go full DC power with the Vape, + a tiny lithium-ion battery, and have awesome bright lights. Either way, it's not something that needs alot of redoing to get everything working properly. Get your ignition, engine and all the goodies; then worry about which wire goes where.

no, it's WAY fatter. the whole header is bigger and "swoop-ier".

there's no "little hammering" some bodywork or "denting" the back side here. you're going to cut up a big parts of it to fit a pipe to support the power level you're looking to achieve.

the early JL pipe is the only one I know that works because I ran one (and still had to trim some stuff due to the cylinder I was running) and geeklion ran one.

all the rest are just a guess unless you have it in hand and the cylinder is mounted and you're fitting stuff up.

some of them are obviously not going to fit, but a whole bunch of subtle nuances will affect the overall fit of a pipe.

One of the most effective tools for tuning (o.a. added 150 kg of lightness) my MR2 was

about batteries; I have been using LiFe (NÓT LiPo or Li-ion.) batteries in my vehicles for some 8 years now and am very positive. They charge faster, loose charge slower, last way longer, weigh a fraction and are smáll.
I wholeheartedly commend them as ´tuning´ goody.
Because of their no-size, they are very easy to relocate. If there is no high current to a starter motor needed, then rerouting wiring poses no challenge either.
So on the 100 you can relocate the battery and remove the tray.

And eliminate all that pesky chassis rigidity.

Nice 100 Sport, btw.

AaronA I read all GRV thread on GSF and this cylinder seems too complicated for me, so to speak, picky about the nuances while assembly...and 20 HP what you want is absolutely not easy to rich, esp. with exhausts you talking about.

There is two ways what I see:
- grab your angle grinder and do massacre on this poor nice 100 Sport. And put proper exhaust(and even cylinder).
- choose more humble setup with Dexter pipe and build good touring smallframe. BTW even with Dexter I'm in doubt that frame will don't need cutting.

How about VMC 144 - aluminium ET6, ET7 or cast iron?
Or maybe VMC ET7 135cc?

EGIG 170 or 180 still there really worth every penny.

as a person that really appreciates stock bikes when they are unmolested, and as a person who really bit off more than i could chew tuning a relatively simple malossi 210, i really keep appreciating the "Just Walk Away" button.

pfft! that's why you just weld in a cross bar!

+1

This is some spot on advice! On every one of my builds i'll remove the coil spring from the shocks and cycle the suspension from full extension to full compression. If something is rubbing, it gets addressed…and there's usually lots to be addressed.

yeah man, its all these (not so small) details that often get forgotten, or not thought of at all; when building a custom scooter. You've done your more than fair share with builds, so you know! So many little tricks to get it right. Thats why these stupid things take so long to do right, and cost way too much! Blood, sweat tears, CASH; some wisdome and alot of dumb luck

It does not even have to a ´build´: Simply a higher custom airbox lid on my ´large´frame P200E was enough of a mod to rub
The large between brackets as it is only large, relative to a smallframe. In absolute references it is still small and a smallframe a diminutive, very compact package. They are SMÁLL.
Seriously, my in absolute terms still dainty elegant 2019 Primavera scoot has a spacious boiler room in comparison.
My apologies for taking up bandwidth harping on about it but the smallframe models, especially the pre-pk ones are like a compact engineering exercise in
miniaturisation.

Alright, so I found a video on Youtube of a guy that has an Egig 170 in a 100 Sport, coupled with what appears to be a Unisex exhaust, I had asked him how he managed to get the pipe to fit without cutting the battery box, and he said all it is, is a bracket that moves the mounting point of the rear shock, and then just a little bit of hammering at the rear corner of the battery box.

The pipe's I'm going to go with is either the MDM Marri Payper K2RR, Egig Viper, or Egig Unisex, however, the Unisex has a smaller expansion chamber compared to the other too, as well as being the most expensive.

S.I.P still doesn't have the Italkast 132 back in stock, so when it comes the time I got the money for the build and order everything, if it's out of stock still, I'll order the cylinder elsewhere.

I'm rooting for Egig exhaust

... and the Egig cylinder kit too

That bracket is needed for all V-range to be able to mount Unisex pipe.
Seems like it works.

Just want warn about Unisex - forget about really low left turns with it.