Vespa PX 125 2012 secundary air system


I bought a month ago a 2012 Vespa PX 125cc (and I'm loving it) in which I would like to change the origin exhaust system to a sip road exhaust.

My problem is that my vespa has a secundary air system (SAS) wich connects to the origin exhaust and does not connect anywhere in the sip road exhaust...

What can I do to cancel the SAS system when installing the SIP road exhaust?

2 pictures of the original exhaust with SAS:


Thanks for your help! :)


When you take off the original exhaust, you're effectively removing the catalyst and secondary air system – you can't connect it to your new exhaust.

So just slap on a SIP road or Sito+ and increase your main jet to 98 or 100 (I'm guessing your's will be a 96 at the moment) and maybe adjust the mixture screw anti-clockwise (richer) a tiny bit.

Might also be worth checking your air filter has the little holes in the heart shape underneath – lets your scoot breathe, if not you could drill it (make sure you get rid of all the swarf) or just buy a p200 one. If you do this, you may need to up the jet by another 2.

It is the best and simplest mod you'll do on your PX. Just make sure you check your plug at full throttle to make sure you're not running too lean.


Hi, electricsun is right about the SAS, just remove it whole, since non-catalyzed exhausts have no SAS (which as a matter of fact is made specificly to let the catalyzer work properly).

About the jetting you have to change the whole main jet "column" and put 160/BE3/102 (with sip road or sito plus), the original idle jet 50/160 is good, keep it.



How do you remove the whole SAS? you just remove the cable and block the pipe ends?

What about the light that stays always on on the dash? Can that be turned off?

it's the light on the left...




Electricsun, Oscar, thank you for both your replies. You’ve been most helpful.

I’m just starting with the PX so sorry if I make some silly questions, but I’m learning. J

After I questioned regarding the SAS system I found out that it is not attached to nothing besides the stock exhaust so as soon as the SIP road arrives it will come out.

I also bought a new air filter to replace the original one.

Just need to upgrade to the new jetting afterwards.


Also I’ve noticed that even all stock, my PX tends to flood at high throttle. Can I fix this adjusting the mixture?