Restricted Milles?

Hi Guys,

I've come across plenty of forums that mention the RSV Mille having a restricted airbox and / or an ECU wire that needs to be bypassed. :confused

Can anyone tell me if that's the case - and if so, which model / year it applies to (including if it's country specific - I'm in the UK)? :dunno

Right, I'm up to date with the airbox restriction now. :thumbup

With reference to the wire-cut mod, is this still applicable to bikes with after-market chips / maps? Mine's got the SBK replica chip IIRC.

Well, after reading some more, I'm starting to believe that the air box mod is a bit misunderstood...

Basically, there are some markets (US and Aus etc) that had Mille's restricted to 72 kW (about 96 bhp) - these used part AP 8134493 as the reduction diaphragm.

However, the UK market (among others) gets AP 8134739 and is listed by Aprilia as the full-power version.

As far as I can tell, all removing the diaphragm does on UK models is make the induction louder, reduce mid range torque and mess up high-speed airflow. :dowhat

If anyone can prove otherwise (i.e. dyno's before and after or any Aprilia docs) I'll be happy to hear it. :kungfu

I'd just like to know, definitively, whether this mod actually helps or hinders a full-power market bike?

I'm on about the tube-plate underneath the air filter. Many people on various forums (including this one) believe that if they remove it, they'll make more power.

I'm saying, do they need to - does it actually help? Some US bikes have a tube-plate that only has a 24mm opening. UK bikes still have a tube-plate but with a much larger opening already, yet people are removing them thinking it's going to boost power even more.

I'm asking if anyone has any real proof of the difference this makes (or if it was ever recommended by Aprilia)?

I believe that a 'proper' mod will work (ie hooked or evo style air boxes), I'm on about removing what some call the airbox 'snorkel'.

I've searched and found dyno results for everything but the 'snorkel' mod.

If you have a link to a thread, could you post it for me?

Th3Judderman said:

I think you should send fusebox (Griff) a pm about your query. As ex technical director of Aprilia UK and owner of Aprilia performance he'd be the best person to speak to.

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I think I will be - I'm thinking of asking him to do my TB sync and idle CO too - sounds like he's got a good rep on quite a few forums. :thumbup

Th3Judderman said:

What you need to think about is that a small aperture will ultimately flow less air than a larger one, hence removing the "top hat" working to flow more air and the engine breathing better.

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I agree with the principle, but it's also a case of how the air flows as well as how much - otherwise why wouldn't Aprilia have installed 60, 70 or even 80mm throttle bodies etc?

From some reviews I've read the mod certainly affects how cleanly the bike pulls on lower revs - I'd also be interested to know what effect riding at higher speeds has on the airbox without the trumpet. Would it pressurise the air box more, or cause a buffeting / turbulent effect.

Also, let's remember that the US 96 bhp bikes have a 24mm trumpet - that's a 425 mm2 hole / area to let air through. For UK bikes, say their trumpet is 50mm (I don't know the exact measurement) , that's a 1256 mm2 hole - already nearly a 200% increase. Without the plate, it's about 100mm ...or nearly 8000 mm2 - 6 times the area of our 'standard' estimate.