Modern Vespa

It is nearly 22 years since I published my air filter mod and it has gone through a few changes and versions since then. One mod I tried at the time was to shorten the induction pipe where it protrudes into the air filter box. This pipe almost extends to the outer cover of the box, leaving just a small gap for the air to pass through. But this mod proved disastrous for performance, so I decided the pipe was a tuned length and left it alone.

Then along came the HPE. This was the first Vespa in a long time that had been designed as a unit, instead of just a collection of parts that worked. The changes had two purposes, to increase performance and to meet emission guidelines. One of the changes was the induction pipe (yes, I know, there are a few different types, as Steelbytes will probably chime in to say) which now had a curve on the end that extended through the diaphragm that I had cut away. This was surely not an emissions mod, so it had to be part of the performance change that gave the HPE it's extra performance. So I decided to try it in my 2018 GTS300.

It took two months for the part (1A011902) to arrive from SIP. I installed it the next day and took the scooter for a test ride. On my acceleration strip it didn't seem any different, but the power felt better at 100-120 kph. But I needed more than seat-of-pants, After weeks of rainy weather I finally got to my test hill on a nearby motorway. My best ever up this long steep hill has been 120 kph, and today after filtering through heavy traffic I accelerated up to 125 kph, and felt that with

Something went wrong on my computer, and I couldn't complete that.
Anyway, as I was saying, up this long steep hill I got 125 kph, 5 kph more than my previous best, and felt with a clear run I might have managed 130 kph. I am just surprised that this mod improved my high speed performance when I expected a low speed increase in torque.

So this induction pipe is my air filter mod version 2. It is not expensive, and easy to install. It does need some cutting of that diaphragm. It only applies to pre-HPE models. If you feel like experimenting, give it a go and report your results.

I am about to make the same mod on my 2015 model GTS.

So the mod was a curved induction pipe? Same size ?
And it made it breath better?

Yes, it obviously made the scooter breathe better. Here is a picture of the HPE air bellows.

Edit: Just for the record, my airbox mods can make the scooter run weak. I counter this by using a Malossi Lambda Emulator to help below 6000 rpm and an IWP158 injector nozzle to enrich the mixture about 6000 rpm. The ECU ignores the lambda emulator above 6000 rpm, so the Malossi box can't help there. The IWP158 has a flow rate of 170cc/min and the standard IWP182 is 158cc/min.

Just had a second run up my test hill, and held 127 kph up and over the top. A significant improvement from a maximum of 120 kph over the last 15 years.

Try it again after Christmas lunch.

Unfair!

So would you say a larger/wider pipe is what makes the difference?

No. I have been told that this pipe is in fact narrower on the inside, although outside diameters are the same. I think it is the added length plus the much easier path for the air to enter the pipe that makes the difference.

Any chance to get a picture or a video (it would be much better) of the 127kmh going uphill?

Sorry, but I don't have a helmet camera, and I wouldn't take my hands off the handlebars at that speed. But all the speeds I have quoted are speedo speeds, not GPS speeds. So you can deduct 10%.

I'll be doing another ride up that hill tomorrow, so will see what speed I maintain this time. The traffic can be heavy, and a bit of nifty lane changing is required to keep going full throttle.

But here is a picture of the hill, copied from Google Earth.

If you do it after your Scottish country dancing gig sans sporran, I reckon you'll get to 130kph.

Gets a bit draughty!

It's been many years since I went scootering in my kilt. My wife and I went off on my scooter in full regalia to take part in a display. I was worried about parking there. I did have my sporran on to keep things under control.

Come on mate, I don't make the rules...

You know as well as I do that without a picture or a video, it simply never happened..

Or we forget all the modern social media BS and take a man at his word.

Have you checked your own signature lately???

Have you guys never heard of photoshopping?

Don't believe me. Get one of these bellows and try it for yourself.

(assuming you have a pre-HPE GTS, otherwise this is all irelevant anyway).

Just got back from my ride. The traffic was too heavy for a clear run, but I still managed to accelerate up to 125 kph up the final steepest part. My tank was nearly empty - probably helped a bit.

Here are a couple of PCX videos.

The second one is more obviously on the stand.

Just to show that a video in today's world may prove nothing. Yes, question everything unless it comes from someone who so far has proved to be trustworthy.

Is that the best you got???