Carb set up.

[mosschops1]

Hi I have got a sip road 2 exhaust fitted to my 2015 PX125, should I be up jetting? It's running ok at the moment 🤔
If so what would be the correct set up.
Thanks in advance,
Alan.

[phattanglo]

An article on the web from some time ago suggested not.
The Euro emissions meant that the problem on post 2011 Vespas is lower down in the rev range.
What you need is a bit richer pilot jet and a richer air corrector.
I have a 2012 px so it's basically the same as yours.
Sorry can't remember which pilot jet I fitted but I fitted a number 8 throttle slide and a 120 air corrector jet.
I have a big bore exhaust similar to the sip road 2 but I'm still able to run the 96 main jet and it runs great.
Hope this is of help.

[mosschops1]

Thanks for the advice 👍

[phattanglo]

Just remembered the replacement pilot jet was a 55/160.
Vespa in their wisdom set the post 2011 models up really lean to get through the euro emissions but they were prone to soft seize coming off full throttle which is not good😁

[mosschops1]

Lol, how do you replace the throttle slide? Is it a simple job? I've had a look at the carb and as far as I can see the jets just unscrew?
Thanks 👍

[phattanglo]

It s simple but as far as I can recall it involves taking the carb out as you can't access the screws which hold the slide in.
The carb is held down with two bolts which for your year will probably be socket heads needing an Allen key.
Unscrew the banjo bolt holding the fuel pipe onto the carb and the two bolts holding the carb down.
Lift the carb up and the little bent rod that drops in the oil pump will simply lift out of the oil pump arm.
The cap that the silver rod goes through is held in with two screws on the end of the carb.
Unscrew these, taking care to hold it as there s a spring under tension inside.
Once this is off it will be obvious how the throttle slide is fitted and removing it is very straight forward.
The fitting of a replacement slide is just the reversal of the process.
When tightening the two bolts holding the carb down they want to be snug to prevent air leaks but don't go mad as it is possible to warp the carb if they are too tight.
The same goes for the fuel pipe banjo bolt.
If you're replacing the pilot jet and you still have the electric start fitted then screw the new pilot jet in and then screw it out 2.5 turns as a rough setting as the jet is a pain to get to with the starter motor in situ.
Hope this is of help.
Cheers keV.