Modern Vespa

FYI: The Uni filter 6245ST will fit over the OEM intake tube without trimming (Filter is 63mm I.D. x 152mm Long). The only fabrication needed is to make a spacer "ring" for the new filter to have something to tighten down onto, as the OEM tube is not rigid. The OEM tube has a nice flare at the end which is in about the middle portion of the filter.

I have not ridden with this yet, so I am unsure of the performance gain/loss. I was previously running a straight pod filter at the end of the throttle body, but was not happy with the cables & wires rubbing on the filter. This appears to be a much better setup, as the filter is not only larger, but should be able to get more cool air from outside.

https://www.amazon.com/gp/product/B000WJFFUO/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Interesting.

Look forward to the follow up on gain/loss or any other pending issue/performance of this mod!

Here's a few more pictures. I used 2.25" OD aluminum tubing for the spacer ring.

Keep an eye on the color of your spark plug as this may cause it to run lean. Most motorcycle engines need a re-map or a power commander when any changes are made to the intake side, the exhaust side, not so much.

Unfortunately, I have made way too many changes to be able to tell if it's faster or why. I can say that the sound is different than with a pod filter... you can hear more of a hollow tube sound. It might be louder outside the bike, as the pod filter was muffled by being under the seat & pet carrier. I am currently running a MP3 400 fuel injector, but do suspect that it might be somewhat lean. My stainless PM-80 exhaust is turning colors... I have been thinking about getting a wideband O2 sensor, but am still somewhat new to that world. This is the one I am leaning ( ) towards: https://www.plxdevices.com/Wideband-O2-Air-Fuel-Ratio-Sensor-Module-p/897346002726.htm



As a side note, I wonder if anyone has had any success with tuning the intake length. An interesting calculator I have been playing around with: http://www.velocity-of-sound.com/velocity_of_sound/calculator3.htm

I enjoy seeing a clean motor compartment on a scooter!

The setup looks great, but I'm not so sure without flow measuring and engine tuning software of reaching success here. This is a very sensitive area.

The velocity software, intake runner length and harmonics is the way to proceed. The NASCAR guys are absolute top of the list tuners.

On another thread, a similar setup would need an extended intake runner to the head, like in the neighborhood of a 10" extension....!!

I believe as well, the exhaust should be modified to match. What goes in, must come out.

Several articles later on, I've gathered the filter, some guys use cones, has to blocked off by around 50%, as the air intake is just too extreme to let the motor thrive.

Good luck with your endeavor. I'd love to read some positive things coming out.

It is a common myth that an air filter with less resistance to flow will work correctly if the mixture can be made richer to match the extra air flow. In practice this never works because it is the resonance of the intake tract that has been destroyed and this has to work sympathetically with the inlet valve timing across the entire rev range. Intake air flow, especially with a single cylinder engine, is dependant on the design of the air filter housing ( plenum chamber ), the length of the inlet tract, and the camshaft profile.
Because scooters with continuously variable transmission often operate over a relatively small rev range it is possible to improve performance by changing the effective intake length or diameter by placing a can over the air filter or by reducing the intake area with some form of restrictor. The only way to be sure that adjustments are taking things in the right direction is by performance testing done in a repeatable way. I used to do a lot of this using GPS tracking over a consistent test route.
With experience it is also possible to gain some insight by listening to the changes to the engine note. There is a certain flat sound which says the engine is not pulling properly and conversely a crisp note answering the throttle indicating that intake timing is good.

Hi roadster, excellent post.

As I understand, maintaining or even raising air/fuel velocity is the key. The larger air intake volume without adjusting the remaining sectors, intake manifold and cylinder head port/valve dimension, would adversely affect port velocity.

For instance, porting a valve chamber to what appears to be more volume, by no means guarantees the head flow works more efficiently. These changes need to be constantly monitored for advanced flow behavior.

I'd like to find out what the best air intake and intake runner length would be, without changing cam or head dimensions, for instance using a flat slider "racing" carb, instead of a vacuum, standard carb.

Keep up the good work AnnDee4444, an interesting topic.

I have a Polini cam, so I am willing to bet that the OEM intake is no longer tuned for the ideal RPM (whatever that may have been). As far as I know, the 200, 250, & 300 all have the same intake box/tube but use different camshafts... so I doubt the factory even considered intake length. Playing with the calculator above, ff you are designing for the first wave the intake valve to tube opening distance would need to be around 35" long (8,500 RPM target). The filter would end up down by the brake caliper . Second wave would be a more reasonable 17".

Yes, I believe what you're looking for performance wise is the 3rd harmonic, about 11" at 8500 rpm.

I'd start from there.

Maybe better yet, start longer and keep shortening till you hit a sweet spot. Still a huge amount of air coming in though.

With the help of https://modernvespa.com/forum/post2316033#2316033
I read the ECU today and found that even with many airflow mods, the MP3 400 injector is way too large at idle for the stock map. The fuel correction would peg itself at 25%, and still read rich. Some slight throttle stabs would get it back to normal range, but without a way of dynologging I can't accurately determine what is happening under load.

Also the motor can't reach target idle RPM, which I suspected since the decompression weight keeps bouncing around (this is with a Polini cam).


I know this is a long shot, but does anyone have an .XDF file for the MIU1 or any other factory tunes?

This past weekend I installed a PLX wideband o2 sensor in the OEM location (well, with a PM80 pipe). I chose this because the kit also comes with a narrowband output to keep the ECU happy.

I was definitely way rich at idle with the MP3 400 injector. I don't know if this was as much of an issue before I installed the Polini cam though... There just isn't as much airflow at lower RPMs with their camshaft profile.

So I switched back to the factory injector and the idle AFR can easily be regulated. Idle speed is actually a little low with the Polini cam, and the decompression weight will not always stay extended, making the idle erratic.

I'm looking getting the Rexxer EVO Scooter now, but can't figure out a good way to datalog properly without a dyno, as I don't think Rexxer can datalog. Guzzidiag/Iawdiag with a screen recorder and laptop in a backpack? https://www.daniele-moto.de/en/tuning/rexxer-user/rexxer-evo-scooter-user.html

I'm very interested in your project. A couple weeks ago I installed the Malossi top end on my GTV 250 using a 300 camshaft. I also installed a Malossi air filter in the stock box and the Force Master 2 controller. I am using map 2 on the Force Master as I still have a stock exhaust. I seem to be running lean at WOT as after ~5 minutes at WOT, it will start slowing down. A couple days ago the temp light came on when I was on the freeway and I had to pull over and wait for it to cool down.

I figured Malossi would have their map well matched to their components. The only reason I got the Force Master was to avoid running lean with the stock ECU map. Now I'm in a rabbit hole I didn't intend on going down. I might spring for that PLX wideband. What gauge are you using with it? Or maybe I should just go find a dyno shop.

I am using the PLX gauge, and it will be mounted in the left knee pad eventually (zip ties for now). I chose this route because I have read that the ForceMaster2 doesn't work well with the 250s, and the PLX has a narrowband output that seems to satisfy the ECU. The PLX screws directly into the existing exhaust bung, and you wire the PLX narrowband output to the ECU's o2 sensor input. I cut the pigtail off of an extra OEM o2 sensor so that I wouldn't be modifying any of the scooters wiring. I have only started the motor with this setup a few times, and never ridden with it (I have a coolant leak that needs dealing with first), but the gauge and ECU seems to function correctly. Another bonus for you is that PLX is located in San Jose.

What year is your GTV? Do you know if the ECU is MIU1 or MIU3? If it is MIU3, you can use IAWDiag to read/write new tunes to the ECU. With the MIU1 ECU, you can only view realtime data. This might still be useful, since you can tell if the computer is reporting rich/lean, open/closed loop, and what the fuel trims are doing.

Also, I wonder if the California gas has anything to do with it. Everywhere else gets 93 octane, while we are stuck with 91 as the top grade. From what I have read, higher octane burns cooler.

I'm pretty sure my ECU is a MIU1. I just went to check but the digit after MIU is smudged. It has the metal face, unlike the plastic looking one in pilaf's picture. My bike is a 2009.

The Force master has 3 pots allowing for some adjustment at low, mid, high rpms. I might try tweaking the high side up a bit at a time and see if I can eliminate the lean condition, although I'm reluctant to do that without the wideband sensor. The other issue with the Force Master is that it plugs into the diag port itself. I'd be unable to use IAWDiag at the same time unless there is a Y cable. Maybe I'd have to wire one myself.

Thanks for the help.

It would be interesting to see what Malossi's mystery box is doing. I would hope that it is not just RPM based, and rather it adjusts based on open/closed loop. Something like this would make sense: idle, cruise (closed loop), and acceleration (open loop). I haven't had very good luck with add-on boxes in the past, which is why I chose to attempt the custom tune route.

If you do have to make your own Fiat 3-pin splitter, it's actually only two wires in the diagnostic port and only one really matters: K-line. Since this is a serial output, I do not know how it will respond when splitting it into a parallel connection.

There are a couple of ECU reading/writing devices out there, but I haven't been able to get ahold of any yet. Right now I am trying to track down a Kess with Ksuite 2.47, or FGTech's Galletto V54. I was contemplating Rexxer, but it looks to be pretty locked down ecosystem that doesn't allow me to upload my own tunes.

What does the spark plug look like? The simplest thing to try would probably be a colder plug.

Anyone have experience using the Malossi emulator with the forcemaster 2 on the cylinder head combo?
Wonder if that will enrich at high RPM.
Kev

That is what they are designed to do, but I have read that the ForceMaster2 doesn't work well with the 250s. I think it might be more of an issue with the MIU1 ECU than the actual displacement or model year.

I now have about 500km on the malossi setup and am pretty pleased with the performance. I'm set on map 3 and the low, med and high settings to about 10-15% (3 o'clock position) as setting to 0 gave me a lousy cold start and initial throttle up. I think this has more to do with lower octane fuel in Australia. I run 95-98 octane here which is equivalent to a few lower in NA I'm told.
Anyway, the forcemaster 2 (250) is working perfectly and I really notice any setting changes.
Might try the emulator at some stage but probably just complicate things.
I do however notice the tappets are much louder than stock even after having them checked after 400km. I think that's the noise I'm hearing but would appreciate any input.
Kev

I also upgraded for my scooter LX 125ie (Model Y2011) with somethings :
- Racing Cylinder MALOSSI 187cc, include MALOSSI Force Master 2 fuel injection
- Gearbox 15/41 teeth, MALOSSI
- Clutch Kit MALOSSI Delta
- Variator MALOSSI Multivar 2000
So, pls help me know to choice the potentiometers better at Min/Mendium/Max (now, it is 0% (at 12 o'clock posision)) in Map Curve 1 on Malossi Force Master 2 for my scooter !
Thanks