Modern Vespa

IF a vespa GTS 300 was nearer 300cc instead of 278cc
surely it would have more power and maybe more speed,

most of the 300cc bikes or bigger have been very close to what they say such 298cc for a 300 or 498 for a 500cc,
why is the vespa so far off its designated size ?

probably just a good selling point. has a better "ring" to it i would assume.

I wouldn't bet on it.

GT125 15hp
GT200 198cc 21hp
GTS250 245cc 22hp
GTS300 278cc 22hp

If going from 198 to 245 only gave one extra hp and going from 245 to 278 gave -.9hp change there is no reason to think that a 298 or 299 would net any additional power. Well maybe some marking power, but with the 300 badge it's already got that.

EDIT: fixed the hp value for the GTS300, old value of 21.1 came from http://www.vespausa.com/scooters/gts-300-ie/specifications.html

The GTS300 is 16.4kw which is 22bhp bang on.

Here is the link to the engine specks which i am sure you already knew
http://www.uk.vespa.com/vespa/UK/uk/Model/Vespa-GTS-Super/Vespa-GTS-Super-300/attachment/GTS_300_super.pdf

If it was 21.1bhp that would make it 15.7kw

corrected, was going of the data on the vespausa.com page.

But still, displacement is not that path to performance.

So is there any fixed formula for what the extra cc's get you regarding torque, power, top speed, etc? I understand the marketing aspect of the bigger number, but I wonder if it equates to anything concrete without actual testing.

The limiting factor on power in the LEADER and QUASAR motors is the size of the valves. The valves are sized to fit into the 125 cylinder and as you go up in displacement the RPM that you reach max power keeps dropping. As a result the power tends to plateau.

The Malossi V4 head goes a very long way to solve this but the extra long stroke of the 300 limits the RPM that you can actually reach.

I think Vespa was going for the marketing "300". Plus the 300 has much more torque. It's pulls away from 250s like they are 150s. The acceleration of the 300 is much better than it looks if you just compare the KW or HP specifications.

Oh, but once a 250 gets going, that doesn't matter. It doesn't take me long to pass a 300. Quite easily, I might add.

No, not by very much.

Aren't the 250 and 300 heavier than the 200? I wonder what the difference is in power to weight ratio.

Has much been done in the area of porting & polishing of intake and exhaust ports on the leader engine? I've achieved significant power gains on my 1949 Harley-Davidson by porting the heads and installing oversized intake valves.

-Craig

When we use the term "torque" we are really walking about an engine with a wide power band. This is really helpful in accelerating a vehicle with gears as it allows you the ability to pull strong through the shift change.

But a CVT doesn't need torque (if it's tuned well), a CVT needs power (since it's got an infinite number of gears). So in practice a GT200 with a well tuned variator will perform almost as well as a well tuned 250 or 300.

Piaggio is inclined to tune the variator for economy (well below max hp) and this lets a stock 300 feel like it has much more grunt than a 250 and the 250 feel like it's got more than the 200. I have to hand it to the marketing and engineers, with the 300 badge and tuned to pull like a train off the line (compared to the other Vespas) the GTS 300 is designed to give the perfect test ride.

278 is metric for 300.

ok lads, interesting answers.,

so what would be a good tuned variator for a gts 300
is there any that will make a difference?

I'll take a 382 cc, direct-injection with a piezo injector, single-sequential turbo, graphite-composite-iron block, aluminum-magnesium-lined head, 15.8:1 compression ratio, biodiesel-compatible diesel installed in my BV350. I'll give up about 7 horses and gain about 16 peak foot lbs of torque, and trade CVT for a five-speed manual with an auto clutch or a DSG automatic so as to take advantage of the low-end torque. My fantasy power train will top out over 80 mph and will garner 110 mpg highway; about 101 mpg running 100% biodiesel. It will trade a little acceleration for strong performance along winding roads and hills which will require few downshifts to power along the roadways @ 39 peak foot lbs of torque starting at only 2800 RPM.

Of course, in reality, a power train like I describe will more than double the price, but keeping with my fantasy, I'll pay $6600 MSRP.

top out at only 80
i do have this in my back yard lol
and this will top out at around 150mph

So, can I ask... Does such an engine exist in some other PTW? ...or is it pure fantasy! Just curious...

Desi B.

I prefer working with the stock variator and focusing on the rollers (or sliders). A good digital tach will help in this as the goal is to be right at the RPM where the engine makes max power whenever you are at WOT (from 10mph-max speed). That's the goal, some compromise comes in but keeping the goal in mind helps you to know if you need heavier or lighter weights.

So you're saying Piaggio should add NACA ducts to the GTS?

Witch, did you ever consider that the rider of the 300 didn't know what they were doing or just couldn't ride ?

Worth considering eh ?

I've had both and once you are past 50 mph there's very little difference between a 250 and 300.

Bill X

I've ridden a 250 side by side with a 300 for an hour and a half on 101 at full throttle, and continuously had to back off the 250 to let the 300 catch up. Heh. *shrug*

Maybe OZ, but you're a skinny little bugger, so your personal drag coefficient is tiny.

haaaaaaaaaaaaaaaa I knew someone was going to say that