Modern Vespa

Our mechanic just got done Dyno testing our shop 300. We dyno'd it in stock form, and also with combinations of Leo Vince exhaust, Super Corsa Racing Power Booster, and Polini variator.

None of the modifications were very good on paper (only a combined 1 horsepower difference), but we got huge gains in top speed. We were able to hit a legitimate GPS verified 91mph (100mph indicated) on the freeway versus the stock machine redlining at 82.5 mph. The scooter does have a Faco midsize windscreen which I'm sure helped freeway speeds.

The Polini variator made the best difference in power. We used the 6 roller version from the GTS250 but put in 12.9gr weights instead of the provided 11.8gr weights.

I'll post dyno charts later today when I get them from my mechanic.

Last edited by Scooter West on Sat, 26 Jun 2010 18:10:43 +0000; edited 1 time

That is very cool. I can't wait to see the charts.


Dave

Looking for some low oomph for my GTV 250. SUggestions?

The Polini variator will greatly increase off the line speed, midrange acceleration and give the potential for greater top speed.

If you really want more power, the 4-valve head is a great improvement. You're welcome to give a call and I can go over options for you. There's also a similar thread to this for the 250cc we did a couple years ago. You can likely search for it.

The problem is that you also ride that sweet Mana 850, leaving your GTV anemic by comparison. Low end oomph? Hop on the Mana. The GTV will never scratch that itch like the Mana will. It is, as you already know, great in its own laid-back way.

Stock 250 vs Stock 300: The Super is much torquier, but loses some of its top speed HP close to red line. They both hit the rev limiter at 9500 RPMs / 83 MPH. One thing about the super is the stock fuel injection runs a little leaner, but does not go super rich like the 250 near red line. Not shown on the dyno charts, the Super hits top speed about 3 seconds sooner than the GTS

I have always been happy with power of my GTS, but it would be nice to get rid of that rev-limiter sometimes!

When are you guys going to shoot for the 100mph mark?

Here:

http://www.motorscooterlandspeedfederation.org/

That might be fun to go watch!

So how much would it cost me to bring in my scoot and have this done????

we went up to las Vegas to do it because the mechanics brother works at a dyno shop. There is a BMW motorcycle shop here in town that does it. I can get you details if you would like.

Will the 4 valve head work on at GT200 without me have to do modifications to the scoot. Meaning, can I use my current cam?

the 200cc bikes also need the 210 cylinder kit and a special piston in order to take the 4 valve head. Your cam is fine.

I am surprised how close the 250 comes to matching the 300 for performance. Of course some would say the 300 isn't really a 300...

Best,

Mark

Yes, but the 250 ins't a 250.....

edited to add... but it's really all about the mid range torque on the 300 which it has all over the 250.

Dave

Heheh but 249cc isn't stretching a point quite so much calling a 278cc machine a 300. Still the scoot I aspire to though...

...edited to add - As a prospective (make that extremely probable) future purchaser, I would be interested to hear some input from riders who have done a lot of miles on both models as to their relative performance in real world conditions.

Best,

Mark

Little difference, of course, but IIRC the 250 is 244cc.

UK brochure says 249cc?

http://www.it.vespa.com/media/gts_250ie.pdf

Best,

Mark

Last edited by MarkTheBlue on Sat, 26 Jun 2010 17:44:26 +0000; edited 1 time

The 250 IS more powerful above 72mph. It seems to be a fuel ratio issue. I think that's why the power booster helped top speed so much on the 300.

Stock 300 Super vs with Powerbooster, stock settings 2.5 red: Makes at little more power with the richer air fuel ratio, Powerbooster is set at the stock GTS setting with 2.5 red.

What is the power booster?

The wife has a 250, and I a 300, she is smaller than I and yet in every situation I can go faster with my 300 than her on the 250, even top speed. She has a chopped (4 inches) full screen and a Vespa trunk; I have a Faco mid size, no trunk. Vespa literature backs up your graphs, but, why is the 300 faster; is it just in our situation?

Stock 300 Super vs with Baffled Leo and PowerBooster 2.5 red:

The power booster is a module that allows you to change the air-fuel mixture.

http://www.scooterwest.com/items/?_pageCCS=t#page=/item_details/Super-Corsa-Racing-Power-Booster-Piaggio-Fuel-Injector--Engine/1706

The 300 makes more torque which is why it's faster.

Note: very loud, but a bit more power.

Thanx;

Another quick question:
So does the 250 go rich because of the electronics, or is it because the motor is running out of air through the air box?

It's the fuel mapping. Not a bad idea really. It gives better power and helps the motor run cooler at full throttle.

I know you can't make money with this (maybe you'll find a way to make that work and be mutually beneficial for both sides), but since you're at it, could you also dyno the GTS with this airbox mod?

So far, we mostly have "seems like" and "feels like" but no hard evidence about the real gains.

Thank you for considering this.

Next time we get the Super out to Las Vegas, we'd be happy to do that.

o--keh

We really would be happy to do that. My response wasn't meant to be sarcastic. I just don't know how soon it will happen.

oh, okay

I am currently running a GPR pipe,
Polini 9 roller and some other minor mods. Thinking about getting the Malossi 190kit. Do you think the power booster would work/be required on a kitted injected 150ie?

Rev limiter is there to protect the motor. At high revs valve float is possible. Valve float can lead to "BANG" "Whaaa?" and empty bank account.

Bypassing the rev limiter safely involves head work. Minimally valve spring replacement, optimally a new cam profile.

These mods will affect power (negatively) at lower RPMs unless integrated with other (major) mods.

Not so simple. Can'o'worms.

P.

We have not had a chance to test the Power Booster on the 10 motor at all.

Mark, I owned a GTS 250 for about three years and a GTS 300 Super for almost a year. I can tell you that both scooters are awesome and I enjoyed riding both. However, as others have said the 300 has torque all over the 250. It is most noticeable when taking off from a start or when accelerating to pass. The torque makes the 300's even more fun to ride than the 250. Other than the engine both scooters are otherwise very similar if not the same in how they ride.

I was under the impression (perhaps wrongly) that when it came to variator weights you can either go for faster take off, more top end or the middle ground but can't get both faster take off AND more top end, is that incorrect?

Last edited by TheCount on Mon, 28 Jun 2010 15:36:11 +0000; edited 1 time

With just variator weights, that can often be true. With a new Variator, you can get the best of both worlds.

It's possible to get very close to optimizing both, but it's a very fine line. Go a little too heavy or a little too light, and you'll lose performance on one end or the other.

Paul Melici of M Tuning has dynoed my mod, and found a small power increase right across the rev range. He was surprised that such a simple pocket-knife mod could produce that result. But I would love to see another independent test.

Windbreaker, I trust when you made the mod, you didn't touch the induction pipe where it extends into the box. I found the hard way that that can have disastrous results.

Also remember that you did Cheeky Thomas' idea of drilling holes, not my one of cutting. Not that I really think that would make any difference, but I have to find some excuse

Mike

That speed increase over the standard almoust sounds unbelivable. Is it due to the variator?

I have a 300 with GPR-Pipe, PM-tuning ECU, Mike´s mod, and I would go for the Polini if it would do this huge difference. I only do 80 mph indicated.

Regards

Sebastian