Modern Vespa

I found this video http://www.youtube.com/watch?v=g9LA2GQLf4Q on youtube where a guy (with an et4) threw away his stock airbox, and replaced it with a truncated conical one, and he claims that really helped performance (after supposedly "messing with the jets and piston", what that means, I dunno)


Anyways, I am wondering if making such a move might put too much stress on the engine. Any ideas? If you want to see his response to my questions, the comments are on the youtube site.

Looks like some kind of K&N aftermarket air intake to me. I actually put one of these on my car a few years back when I was replacing the exhausts and some other bits and pieces. I'm no car freak but the way it was explained to me (and I am sure someone here that is more mechanically inclined will confirm or deny this in a non-insulting way), is to imagine the difference between breathing through your mouth when exercising or trying to breathe through a straw in your mouth. More air going into the engine makes for more horsepower, and these cold air filters are an efficient way to achieve that.

FWIW, my car did have a little more "oomph" (that would be the technical term) to it after replacing the stock air filter and box.

Would have been nice if he had actually started it up in the video.

Too tired to try and look but....
Aren't there a couple of post in here about replacing stock filter does little to actually improve the scoot...?

Those free flow air filters just seem to suck more gas, because you have to re-jet them so high.....or you will blow your motor....
What I did is to keep the original air box and put in a Malossi Red Sponge air filter.......

When you say what you do about the free flow filters, is that for all engine types, or for two strokes? Also, where would I find a malossi red sponge? I found a malossi filter, and maybe a sponge but for a 250. Would replacing the sponge with a malossi one really make that big a difference?

I did find another topic on this, but it just ended without the guy ever saying if he put the filter on his et4. I did find someone who did, and claims after fiddling with it for "a long time" he got it to work, and with notable increase in performance.

The problem is the CV type carb which relies on a calibrated amount of vacuum to lift the carb slide open. When you remove the restriction of the airbox, there is not enough vacuum left to lift the carb slide, nor is the carb jetted to mix enough gas with with the increased airflow even if you get the slide to open. Add to that plug access issues with the et/lx and figuring it out becomes quite the task. It would take someone with some real specific technical expertise and some motivation to figure it out. Best bet is to replace the CV type carb with a similar sized 4 stroke pull slide carb and jet it with the engine out of the bike on a test stand. I have a buddy threatening to do just that. I plan on letting him figure it out and then just applying it to my motor.
It has occured to me that a spring type valve on the airbox that opens up when the vacuum is great enough, along with a larger main jet could do the trick. Kinda like the one on my vacuum cleaner that opens up when I put my hand over the suction hose in order to save the vac motor. Feel free to work that out and let us know.

What ScooterMarc said. He's dead on. Don't mess with the airbox on an ET4 unless you plan on switching carbs as well.

Max, I have a Malosi Red Sponge guide that came with my air filter...I know for a fact that the Typhoon filter for mine is listed wrong, guess they use the 17.5mm Delorto Carb here, and a 12mm Carb in Europe....
Does one fit on the ET4?

They don't make a red air filter for the ET4 that I know of. You can modify the airfilter in the ET4 stock airbox if you like. But it likely won't do anything. The air filter itself is not the bottleneck, it's the snorkels in the airbox.

Would replacing the carb with a slider one be worth it (assuming you got the other filter, and spent all the time trying to fine tune the jets and the like) as far as performance goes? If you do, would that have a negative impact on the life of the engine?

I do believe it's the bottleneck in the system, so I imagine it would help. Especially if you already had a 190 kit and an exhaust.

Malossi do not make a panel filter for the leader engine, You can buy polinni filter sponge from Beedspeed and cut to shape. But to be honest I noticed no difference in the scooters performance.

the leader engine seemed to get left out a bit when it comes to tuning , I tried to buy a de restricted Malossi ecu for my ET4 to be told that there is not one for the air cooled leader just the LC engine,

I bought A PM tuning pipe and thought at that price it would make a difference, really nothing noticeable apart from it looks and sounds great.

UNI makes a filter for the ET4. It's about $15 online.
There are a lot of problems with cone filters. One is that they give way too much air. The CVK carb needs a little resistance to operate properly.
Another is that they have no protection against water, like rain, or a puddle, so it gets sucked into your engine.
If you change the displacement and add a pipe, you might need to increase the air intake a little bit, but you don't need to give it more air than it wants or needs. If you do decide to get a cone filter, and then are disappointed with how it bogs at high speeds, you can use duct tape and seal it off little by little until you find the sweet spot where the engine gets just enough air.

These open air-filters made for tuning. But, If you start tuning your scooter, you have to change the carb, the exhaust, you need a stronger crankshaft, and a lot of other parts. It is a very problematic game. There are a lot of scooter for tuning, but the Vespa is not made for it.

Although, that Vespa on the video, has a personality disorder. It thinks, it is a Ferrari...

Will be removing the stock airbox from my GTV and installing a K&N filter instead. They make all types and sizes for any application you want.

What is your aim with that filter?

Getting rid of the stock bulky airbox, cheap easy to clean filter and more air.

I see, but more air - the motor need more gasoline. Will you change the calibration of the carb/injector?

His bike is fuel injected, so it will compensate some, but not enough for a cone-style filter. We were not able to pull the fuel curve in enough for our liking on a Dyno with a pod filter on a GTS. But, people are running them.