500 airbox mod removing restrictive inlet tube
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Addicted
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 566
Location: tampa
Fri Sep 27, 2019 11:16 pm quote
so I removed the tube from my box last year when installing new stock filter. I first got the bike. put 4000 miles on it since. a few days ago I checked filter and it looked like it was doing its job. trapping lots of debris. florida is very sandy. cleaned the box. but during cleaning I noticed I never bothered to port the inlet to the box. looking at the inlet tube to throttle body I said to myself thats got to be a restriction. sure enough. taking tube out is step one. but the inlet needs to be ported out. bike picked up quite a bit of zip. very happy .

fast forward to tonight I am reading unrelated thread and the airbox discussion came up. removing tube allows air to bypass straight to the engine. I am thinking to myself, "no it cant be" I have been running bike for a year unfiltered. couldnt wait till morning to see if this was true. so I go outside to open box again. here is what I found.

so it is true. but there is a saving grace to it. the air filter still functions quite well as an air filter. I didnt clean the filter a few days ago. Only cleaned out the debris inside. those debris are all on the dirty side of filter. as it turns out air has mass to it. doest make right hand turns unless forced to. so the air still does go in to the cleaning side of filter first. not gonna go backwards any easier its easiest path is through the filter. add to the fact there is a fresh mist of oil coming from breather that is added to filter side. add to that the inlet to engine is high up in the box. the result to me is yeah , nothing heavy is gonna make into the engine. the lighter very small mostly just organic material making its way into engine doesnt hurt anything. it just burns at 1800 degrees combustion temps. it is known that even alloy shards will burn and not hurt your rings or cylinder walls. so I am officially relieved so much to the point I dont think I am going to add a dividing panel.

three days of filtering on plastic parts. 3500 miles on filter. only lightly shaken to banish the loose debris then put back in.





Hooked
2016 MP3 500 Sport
Joined: 21 Jun 2007
Posts: 134
Location: Indianapolis, Indiana
Sat Sep 28, 2019 6:40 am quote
Nice! What year is your MP3?

Marty
Addicted
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 566
Location: tampa
Sat Sep 28, 2019 6:44 am quote
2009
Hooked
2016 MP3 500 Sport
Joined: 21 Jun 2007
Posts: 134
Location: Indianapolis, Indiana
Sat Sep 28, 2019 7:07 am quote
Thanks. I have a 2016. Any idea if the results would be the same?
Hooked
2009 MP3 400
Joined: 11 Jun 2007
Posts: 162
Location: Sayre, PA
Sat Sep 28, 2019 7:58 am quote
Also entirely possible that by modifying the airbox for better flow that you have exceeded the parameters that the fuel mapping can compensate for and the motor is running lean. That would account for the more pronounced knocking/detonation you describe in your other post.

Don't know if there are any specialists out there currently that work on Piaggio ECU's and can work up a new/better fuel map.
Hooked
2009 MP3 400
Joined: 11 Jun 2007
Posts: 162
Location: Sayre, PA
Sat Sep 28, 2019 8:08 am quote
Been wanting to poke around this myself actually. Just haven't gotten around to it yet.

DIY Diagnostic tool for injection Vespa's with MIU ECU
Veni, Vidi, Posti
MP3 500, GTS 250 (both 2008 MY), 2012 Honda NC700 DCT
Joined: 02 Mar 2013
Posts: 5905
Location: Madison, Wisconsin
Sat Sep 28, 2019 10:01 am quote
Careful with that airbox mod, you need to block off part of the inlet to be sure all the incoming air is filtered.

I have had mine done now for ~4 seasons and ~22,000 miles.

Airbox modifications
Addicted
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 566
Location: tampa
Sat Sep 28, 2019 11:22 am quote
I ended up tweaking more. made holes a little bigger that leads into the filter area. and added small flap that blocks the majority of path to other side of box. the space next to the flap is where the oil box is. and there is flat area there that straightens the path.




Veni, Vidi, Posti
Neutrino MP3 492.7 AK, 2013 Moto Guzzi Norge
Joined: 29 Mar 2008
Posts: 21579
Location: Harriman, Tennessee, Tn
Sat Sep 28, 2019 2:34 pm quote
I do NOT recommend jerry's style of airbox mod. this will still let unfiltered air into the engine.

If someone wants to do an airfliter mod PLEASE do it the right way and make it like the ponydrvr mod.
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8343
Location: Ashburn, Va. Home to the Internet
Sat Sep 28, 2019 5:16 pm quote
old as dirt wrote:
I do NOT recommend jerry's style of airbox mod. this will still let unfiltered air into the engine.

If someone wants to do an airfliter mod PLEASE do it the right way and make it like the ponydrvr mod.
But just a little dirt gets in and eats the cylinder, piston, valves and some gets in the oil too. What a great design
Enthusiast
mp3 500 2016
Joined: 30 Dec 2011
Posts: 80
Location: singapore
Sun Sep 29, 2019 4:27 am quote
So wats good for to do the airbox mod?
I had just changed to malossi air filter n found that my topend loss
I only had rapid bike installed with original pipe.
Ossessionato
2016 Vespa GTS300ie abs/asr/ess Settantesimo '70'
Joined: 11 Jun 2011
Posts: 2677
Location: East Anglia, The power house of the UK
Sun Sep 29, 2019 4:34 am quote
I view Jerry's mod with suspicion. I can see several issues with it. Please don't follow that mod unless you want to encourage real problems with your engine.
Addicted
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 566
Location: tampa
Sun Sep 29, 2019 5:45 am quote
yes people sorry I forgot the disclamer title

"dont modify your box like this, its the wrong way to do it."

just noting there are two bikes in tampa that are running prefect after 12,000 miles combined. we have been lucky all damaging engine particles are still magically being trapped by the filter. as evidenced by my own eyes.

for my own notes. the last tweaks I did slowed the bike back down. there is HP hidden in this box. better to get a pod filter if you can withstand the noise. I dont like noisy so I will keep tweaking till I get my cake and eat it to.

I test my mods against my friends beo 500. combined weights are within 10 pounds so the bikes perform extremely close. but he has always been just a tad faster. the simple mod that left a smile on my face resulted in me beating the beo for the first time. the final tweaks made the bike slower again. the beo runs malossi filter, me stock. so we switched filters. no wala. filter does zero.

then removed flap to see if power come back. it did not. so my research continue.

sidenote. beo with rear fender has substantially less debris in his box.
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8343
Location: Ashburn, Va. Home to the Internet
Sun Sep 29, 2019 7:20 am quote
jerryd wrote:
yes people sorry I forgot the disclamer title

"dont modify your box like this, its the wrong way to do it."

just noting there are two bikes in tampa that are running prefect after 12,000 miles combined. we have been lucky all damaging engine particles are still magically being trapped by the filter. as evidenced by my own eyes.

for my own notes. the last tweaks I did slowed the bike back down. there is HP hidden in this box. better to get a pod filter if you can withstand the noise. I dont like noisy so I will keep tweaking till I get my cake and eat it to.

I test my mods against my friends beo 500. combined weights are within 10 pounds so the bikes perform extremely close. but he has always been just a tad faster. the simple mod that left a smile on my face resulted in me beating the beo for the first time. the final tweaks made the bike slower again. the beo runs malossi filter, me stock. so we switched filters. no wala. filter does zero.

then removed flap to see if power come back. it did not. so my research continue.

sidenote. beo with rear fender has substantially less debris in his box.
If you race that is great, but you lose low end power and torque doing mods like this. All you gain is full throttle power.

If you ride around town on the street, leave it alone.
If you want to have the fastest not as fun to ride around town MP3 go for it.
Veni, Vidi, Posti
2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8343
Location: Ashburn, Va. Home to the Internet
Sun Sep 29, 2019 7:22 am quote
It's like this, are you riding on the street or on the race track?
Addicted
2010 gts 300 super. 09 MP3 500 lite
Joined: 02 Apr 2013
Posts: 566
Location: tampa
Sun Sep 29, 2019 8:05 am quote
its a street bike web. I am not one to modify while ignoring what you are ruining. thats pretty much my definition of drag racers.

my bike drives absolutely fabulous in every way shape or form. its 60-80lbs lighter than anything I can find on this forum or anywhere else. it performs far better than when stock. no comparison. its a blast to drive and twist the throttle.

any questions?
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