Modern Vespa

Hi, Just bought a 2012 Gts300 only 3k Miles, 200 miles ago it has been upgraded malossi 9 roller variator, gear up kit, exhaust with remap and cat removed, it’s much slower that the previous 1 I had which just had a scorpion pipe on it. It’s not got enough revs or Reving hard enough, any thing I can do to get more power or should I take out the gear up kit. Some advise would be most welcome, stepping up from 2 stroke, don’t upnderatand tuning on these new models, neither did the previous owner by the look of it🙄

The gear-up kit is really to make the scooter go faster. But you first need the extra power to drive it. I wouldn't fit one unless I first had the Malossi V4 cylinder and head installed for the extra HP. Then the up-gear kit would give a little more speed and also keep the revs lower when riding at high speed, good for long-distance cruising.

So either fit the V4 kit (expensive) or remove the gear-up kit. Do you have the original gears at hand? Do you want to do long distance high speed cruising?

Greetings:

Mike is quite correct, taller gears won't make a vehicle faster unless drag is reduced by a tailwind or you're heading downhill. You can pull the overdrive gears, but that's a ton more work. assuming you still have the stock gears. But there is Plan C:

Reducing the variator weight load will compensate for the taller gears, at least once the clutch is fully engaged and the variator begins to, er... variate. I suggest you pull the variator, get a gram scale and see how much load you have. Reduce by say 15 or 20 percent and your revs will come up once underway. Let us know what you decide.

Hi Gents, thanks for your help. I am told that a main part of my problem is the GPR exhaust which is ‘e’ classed, it’s stopping the engine making the power. I would be better off with a standard pipe or PM / scorpion, do you have any thoughts, I can say my experience on 2 stroke would agree, but this is a whole new can of worms.

Aftermarket exhausts can give a tiny gain in performance, but they are mainly fitted for looks and sound.

I have an Akrapovic exhaust sitting in the shed. I found it too noisy (but the wadding has been re-packed as couple of times) and I now stick to the original exhaust. Paint that heat shield black and it looks a lot nicer.

Ok, I have just ordered a second hand standard pipe, should be with me in a couple of days. Let’s see how this changes things. Cheers

Greetings:

If it improves even to Acceptable, that has to be some dog of a pipe you have now. Check the intake side while your tools are out. Filters sometimes congeal and limit airflow after 8 years or more. Order up some variator weights. I have a feeling you'll be lightening at some point.

Probably best to look at your powerplant as a system, with intake, cam, and exhaust all being designed to work together. Change one without changing the other two, and you probably won't see much benefit, and may see a loss.

If the pipe is designed for higher revs, but the stock cam won't let the engine make power there, it won't help.

Power requirement goes up as the cube of speed. So incremental increases in power aren't going to affect top speed much.

Hey Guys, Up date for you. Thanks to everyone for your input. I have now replaced the pipe with a standard second hand one. Wow what a difference, pull away reasonably lively and top end I took to 75 mph, on a wet slippery road, so still had a bit left in it, bare in mind this is SIP / real MPH as opposed to Vespa mph🤣🤣 so already have 9gram rollers, and up gear, with out spending £1k plus how can I get a little more grunt, air intake, electrics, speed limiter, does porting help 4 stroke? Don’t hear anyone doing this or skimming heads.

I understand adding a nitrous oxide system can improve top speed considerably, though temporarily.

Unless you have quite a bit of experience 'hopping up' engines, likely to do more harm than good messing with them. In the deep distant past, factory engineers tended to be less interested/capable of extracting top performance, but most modern engines put out about the max they can, consistent with noise and emissions standards and fuel quality. Almost certainly would want to have a number of heads available, and need to have/build some sort of flowbench to measure improvements as you ported.

I expect you could mill the head/cylinder, put in a high compression piston, port the head, maybe put in bigger valves, convert it to run on E-85, and substantially increase your horsepower, although you'd then need to upgrade much of the drivetrain, as well as the cooling system, to handle it. Mileage would suck, of course. I guess if you had a lot of time and money on your hands, and ideally, access to a dynamometer so you could actually tune the engine, it might be fun.

Or you could buy a scooter with a bigger engine, enjoy all the benefits with none of the hassles.

See post above for relationship of power to top speed. While the CVT allows the engine to operate in a relatively narrow rev band, might find that a highly tuned engine with a narrow power band might not accelerate much better than stock. And require some very careful CVT tuning.

Thanks Jimding, really looking for a easier solution, someone had been tinkering with this that didn’t know what they were doing, spent a load of money and ended up with a slower scooter. I’ve noticed they have put on a small mushroom air filter on a pipe cutting down the main air filter. Would love just to make it Rev a little harder, might now spend money on a pm pipe now I know the main problem was a crap exhaust.

What was the exhaust that you took off?

Sounds pretty damn unusual that this was the cause of your issue on a gts

Year it was a GPR most of the Tuning specialist slated it and they were correct, apparently it’s ok on a standard engine but not when you increase the gearing. Thinking of a PM 68 and a lambada tuner, thoughts please, it’s bolt on power not top speed I need.

I'm using the Arrow 53525ANN and Malossi lambda emulator on my 2019 Supertech.

Happy with this, feels and sounds good. Originally bought the arrow without the cat but was too angry so added the cat after. if I had a mapping on a dyno I would probably remove the cat and lambda ...

https://www.arrow.it/en/assembled/1652/Piaggio-VESPA-GTS-300-HPE-2019

Last edited by steelbytes on Mon Feb 22, 2021 4:17 pm; edited 1 time in total

When you say too angry, do you mean noise or power, did you notice a increase in bhp.
Thanks

noise.

the exhaust didn't make a noticable power difference on it's own, but when I added the lambda very shortly after that did. I always planned them as a pair ... theory was more in more out

Ok thanks, that’s helpful. I’m leaning towards a pm68 apparently make extra 2 Hp across the spread on its own and is under £300 so with the lambada tune should be hopefully a match.

If the bike was not hitting the rev limiter before then you don't need to gear up.

The exhaust will allow the engine to rev better.

The emulator won't do anything above 6000 rpm.

The emulator also has a lead going to the injector, so it is not just lambda emulating. I would love to know what it it doing there, but it is impossible to get any information about it from Malossi.

not on the emulator I purchased and installed last year on my supertech.

iirc when I was making sure I purchased the correct one there was mention of a 2wire and a 4wire version. mine is the 4wire. I think the older gts needed the 2wire? maybe the 2wire needs another lead to get power and the injector is simply a convenient place

You are probably right. My 2015 GTS300 is two wire with an injector connection. The other 2018 model is four wire and no injector connection. I recall that my GTS250 was also four wire and no connection.I had thought it might be monitoring the engine revs to do some more fancy manipulation.

I’m still waiting for my PM pipe, they say there in stock but they are still making the brackets I noticed that my back tyre is a 140 depth I think the previous owner wanted really tall geared , low reving slow scooter, maybe trying to save mph. I think if the new pipe finally arrived giving it’s supposed to increase power, it might have enough to make pul away lively. There is also a rubber pipe that comes from the top of the engine that would usually run back to the air intake filter box, but they have discontinued it and terminated the pipe in to some sort of small mushroom air filter, it does get a small amount of oil back into it. Is this more silliness or of benefit does anyone know... the saying “ a little knowledge is a dangerous thing” come to mind .

If you've got the 9 roller Polini variator, you need to get lighter weights to pull the upgear, and even then, without more power, will will probably lose speed and acceleration over stock, if you compare real numbers and not what it feels like it's doing. A total of 60 to 70 grams are about where you are going to want to end up. Right now, if I understand you, you're at about 81 grams. That's close to stock on a 300 GTS. The upgear kits are like sticking a bigger sprocket on the front and a smaller sprocket on the back of a bicycle. You do pedal less to go the same distance, but it's harder to pedal.

up gears are largely miss understood.

they make bike faster? depends on how you describe fast.

if faster means higher top speed, than yes gear up kit is faster.

if you are after better acceleration, than no to gear up kit. acceleration is always slower with gear up kit. doesnt matter what other upgrades are in place.