PX150 jetting for SIP Road


Just wondering what the best jetting setup for a 2007 PX150 would be with a SIP Road exhaust. I have the drilled air filter and sito plus at the moment.

Am I better off with my current BE5, 150A/C – or should I use a BE3, 160A/C? Any advice on the best idle jet would be helpful too. I know there's no exact answer (particularly for the main jet) as all engines seem to run differently. I just need a good place to start, as there are so many combinations I will be swapping jets and doing plug chops for years to come!

I would be grateful for any help.

Hi there! The right jetting setup for a px 150 not catalized is 160/be3/main jet, and idle 48/160. With a standard exhaust such as an original piaggio (not catalized) or sito (the original-like) the main jet is 100 for autolube and 102 for non-autolube. With a sito plus or a sip road 2points extra should be sufficient, so for autolube 102; in any case no more than 104. 106 (6 points extra) is too much and may limit the engine to reach its maximum revs thus having less top speed. Greetings. Oscar

Plug was a little light with a 102 main, 106 was about right colour-wise but then struggled to push it over 50mph. Mid range is really smooth with the BE3 and has plenty of pull, just runs out of power 3/4 to full throttle.

If my memory is correct the standard jet size is 102-105 for vespa 150 models. I would think that a little higher would be a good place to start and work down.   110 should be a little too much but would be a good place to start with the be3 and 140 or 160 a/c. Im always inclined to jet a little rich as its safer.

Thanks all for your help.

Settled on a 104 and seems to work OK. Pleased with everything except full throttle, just not able to cruise at around 55mph-ish without feeling like I'm thrashing it, perhaps I was expecting too much from a 150.

177 kit next then – a whole new can of worms!

I have a SIP Road exhaust. I have set the jetting up as you describe apart from the idle jet for which I have a 48/100, How important is it that it should be 48/160?  Also the plug I am using is as suggested for the original cat version, a Champion RL82C, seems to run nicely. Strangly the NGK BR6HS which is meant to be the equivilant causes problems. What plug would you suggest is best ?

Yes i wont argue but only to say the air filter has been drilled so more air will weaken the mixture.Id start with 106 and see how she runs.

Sorry for slow reply… you'll have sorted it by now I guess…

I put the exhaust bolt in then levered the base of the exhaust up with a block of wood until enough was hanging on the exhaust stub of the cylinder. I ground off the original clamp and put a 'U-clamp' on, seems to have done the trick.

Great exhaust – once they're on properly

second thoughts 110 is probably too rich for a standard 150 barrel ....107 ?

Thanks for the reply...

After struggling to get the SIP road on (exhaust stub and hanging bracket didn't seem to line up), I haven't had a chance to test it because of bad weather. I've dropped in a BE3 with 160a/c and a 48/160 idle as that's what is in the original P150 I believe, highest main I have at the mo is a 106. Sounds good and has a different note to the Sito+, although I thought it'd be a bit quieter from other comments. Can't wait to test it out.

sounds like 104 might do the job

[quote user="ElectricSun"]
After struggling to get the SIP road on (exhaust stub and hanging bracket didn't seem to line up...[/quote]

I have a 2005 PX150 and I'm having the same alignment problem you are describing.  What did you do to get the pipe on?

Tom W