Modern Vespa

Thank you for the information Mike.

Additionally, I ground down the wquare pieces that probably disrupts smooth flow of air. Nice mod.

I read through this whole thread. my first thought is I wish I hadnt chucked spare airbox I had for my project 300. my second thought is changing the shape of the U in the divider is likely doing nothing. its simply not a restriction there. all the extra flow is coming from reducing the pressure drop across the rectangular channel. the biggest improvement would be seen by cutting it open nearer the entrance. as opposed to the v mod near the tail end.

I am also pretty certain the ECU is not capable of correcting for the extra airflow. the 02 sensor feedback can only correct for idle and light cruise conditions. 02 feedback is ignored during acceleration. the change here is likely just not big enough to cause a huge a/f swing.

I think I will mod mine by making the whole channel bigger with rounded edges at entrance and exit. this should maintain its original design which is to distribute air to the filter evenly by dumping air at top of box. and second to insulate my larger channel with sound deadener . I will snap pics and report my results.

You might like this thread: http://www.apriliaforum.com/forums/showthread.php?243793-Project-Vespa-300-SUPER-(should-end-up-living-up-that-name)

I was putting off modding my box. Since installed this new exhaust and maybe before I have been battling detonation WOT. A few days ago I installed a 170cc injector to replace the factory 158cc. It was immediately noticeable difference with the extra fuel. and it took several days of driving around till it felt as fast as it was. So I figure it was safe to lean it out some with the airbox mod. only to find I was running around with no dang filter. dont think I will be able to ad to seat of the pants difference.

My attention was on the channel only. and the entrance seemed like a bad design. Would like to talk to engineer on why they have that little lip that looks like all it will do is cause turbulence at the entrance. I used a heat gun first to bend it out of the way. then I ground the lip all the way around so the glue would have something to stick too. on the channel itself I heated the end and flared it. and cut a smallish relief hole. I think flow through channel is greatly improved. I will be ordering a malossi filter as I miss the airbox sound. was kinda depressing taking it for its first spin with a filter onboard. way to quiet.







and at same time this was done my friend was doing his beo 500 box. I was floored at how restrictive the intake snorkel is on this 460cc 39hp bike. it wouldnt pass a nickel. he got much more seat of the pants power.

Hello,

I have a 2019 vespa gts 300 hpe.
Read about the air box mod.

The airbox i have is the same as the older model except for the longer hose. Not sure why they made this hose longer, cant see why this would be better.

Think im going to do the V on the box inlet, also tempting to do something about that long hose.

Foto

It looks like air flow could be improved by cutting off some of that pipe, but don't be fooled. I tried that on my filter and the result was disastrous. That is a tuned length for induction pulses, and cutting it might have the wrong result.

Please experiment and let us know the results, but if you attack that pipe, be prepared to buy replacement. Just opening up the snorkel might be all you can mod out of that filter. The Malossi red filter element also helps, but I didn't like the induction noise that came with it. If you get really serious about it, consider replacing the whole filter with a K&N one.

Did only the box inlet, didnt had a spare pipe so left that alone, maybe in the future, but i also think vespa probaly had a reason to make the pipe longer.

Just ride 20km and im not unhappy.
Its not really faster looking at the 0-60 time, from the start is feels faster and the gas response feels better. It makes a bit more noise but that i like. It feels like the bike is happier now and can breath normal😜

That is about how much mine is cut away. Some guys drill holes all along the snorkel. Depends on how likely you are to get water splashed up there. I avoid riding in the rain if at all possible. Have a car for that!

Maybe the snorkel is also to keep gravel out. If you only ride on smooth dry roads I guess the snorkel is not needed at all.

Very soon going to adjust the inducation pipe. First going to cut to the halve of the airbox and later then might all of it. The boxvolume is now made less becouse of the longer induction pipe(not even half of the airbox is used). This could be for noise reduction or it really has a reason and cutting it, is going to make things worse, we will see. If not okey i just fit a new one.

Well today i have modded the pipe.
I had the idea to first cut half of it, test it and then all of it.

So i cut halve of it as seen on the foto and tested it. Make sure the pipe and the box is clean after.

I have not experienced any negatives. Its makes a bit more noise and on full trottle is feels more aggresive/powerfull.

If i had to chose for this or orginal i would chose this.

Maybe in the future i will do the whole pipe, but this is fine for now and maybe all of it is too much.

Foto

Picture is upside down

I wonder if this longer pipe fits on the older models. The longer length should be tuned for a higher RPM.

I found that shortening the old version of the pipe was not a good idea, so maybe lengthening it using the new pipe will result in something good. Keen to hear your results. Certainly looks good for smooth air flow.

interesting. on the HPE in asia pacific we have a different airbox without that pipe. see pics

I would not recommend cutting the pipe like seen above. flow into any pipe can be increased significantly by adding a velocity stack on the entrance. thus eliminating the velocity stack as seen here was not a good idea. when the sound of intake is changed it can be misleading to whether or not there was a performance increase.

interesting there are two completely different box designs

Steelbytes, that filter does not look at all conducive to good air flow. Robert12345's mod looks good, and I have ordered the longer induction pipe to try it. But if it increases air flow much I may have to fit a larger injector, or install my Malossi Force-Master and set the mixture richer.

In my old-type filter box the induction pipe extends almost all the way to the outer box lid, with just a small gap for air to enter it. And the inside of the lid has a raised pattern on it which will also create turbulence.

I don't have a pipe to cut!

The design that mine has first appeared several years ago on the GTS125 ...

Yup. I was replacing it, that's why i had the box open.

It was getting dirty very quickly because of some poor piaggio design where the air inlet would suck some air from the engine bay which of course is dusty on gravel roads. Had to use some foam to seal a gap before it would suck from the correct place which is under the front of the seat where the helmet pegs are

My take on the mod. Bell mouthed snorkel inlet. Trimmed out the grid on the lid for better laminar flow. Didn't mod the snorkel end, think this is important for velocity. Doubled the size of the cutout between chambers with a bridge added for filter sealing.

Want to try trimming the rest of the grid and completely removing the wall between chambers and maybe cutting an inch off the end of the snorkel. Ran out of time, what you see here took the better part of a weekend.

@bluecloud- did your mod bring a positive effect?

It's louder. I think the function of the grid I cut out is to reduce acoustic resonance.

Performance wise, hard to tell, at least no negative effect, unlike when I attempted to modify the airbox on my carbureted scoot. If anything maybe a bit snappier response when you crack the throttle from a stop.

Functionally the only thing I really changed was opening up the divider between the 2 chambers a bit. Felt like it might have been running lean/hot for a couple days, but ECU was able to compensate.

I went conservative on this first try as I didn't want to down my scoot. I've got a 2nd airbox on the way I plan to completely gut. Could go as far as a pod filter but over the years I've had pretty good results gutting factory airboxes with less noise than an open filter.