Modern Vespa

I am brand new to this forum, and am looking for some wisdom, expertise, and advice...

I just picked up my PX150 yesterday, and it's AWESOME, but I COULD use some extra power. I've heard a lot of good things about pipe upgrades, but they require "upjetting." Can anyone tell me what is the best all around pipe I can get, what upjetting is in layman's terms (i'm assuming something w/ the carb?), and if an air filter/intake mod is a good idea as well? And any extra advice? Thanks so much!

The easiest, quickest, cheapest and most effective performance mod you can make is to swap out the stock pipe for a Sito+. One mechanic told me it's the pipe these bikes should come with standard, and it made a very pronounced difference in my Stella (substantively the same as a PX150) right away. There are other (bigger, badder) pipes too, but the Sito is just about the least you should do. (But note, almost anything you do will void whatever warranty you have. I waited till mine had expired.)

Upjetting is a simple process requiring a screwdriver, a sampling of jets and a trial-and-error approach that others (here and at StellaSpeed) can detail better than I. You must upjet or risk seizing your engine by starving it of fuel and oil.

Have fun with your new PX!

Give me a call if you would like to chat about options!

not to direct you to another site, because this site is great...

but for the PX150 you can get lots of upgrading info at stellaspeed...the stella and the px are almost the same machine and almost all parts are swapable and stellaspeed is all about changing pipes and upgrading clutches and such...you can find lots of threads there about getting more mph...

sito plus is the first thing to do

g

Great! I appreciate all the replies! I'm looking for definitely a performance upgrade with the pipe, but I want it to remain relatively quiet...is the sito plus still the way to go? Also, I don't know if it's just the break in period, but if I throttle a little quicker, the engine almost stalls out, like it's running REALLY rich. Is this the case? I've heard that there is no needle on the stock carb to adjust the fuel/air mixture...true? Is it a good idea to just swap out the carb, jets, and pipe? Thanks so much!

The Sito is perhaps the 'politest' pipe you can swap to, short of going to a non-cat stock pipe... but what's the fun in that? Mine just took on a more gutteral pop after upgrading.

I had some problem with mine bogging at high revs too... after much tweaking and grumbling on my part, it was cured by a new (under warranty) carb. But again, there are people better equipped to advise you on the upgrades you're talking about... but a new 24/24 carb is a common upgrade too. Motorsport would be a good place to call.

carry some extra plugs...you will foul sooner or later...the carb is the hardest part to dial in on the PX...

sito + is louder than stock, but not too loud...a pop pop pop sound...it gives nice power up hills and faster off the liine, but not much added to the top end...great for city riding...it is THE pipe if you have a sidecar, so that tells you something about the lowend and pulling power of it...i also think it is the nicest for "point to point" shifting, ie, it has no dead spots

if you want to go over 60, don't get the sito--if you want to go 50 to 55 with good off the line power and nice up hill speed, get the sito+

g

So here's the difficult question then... say I wanted a little more high end, but still the "politeness" and torque of the sito plus, is there more of a universally powerful pipe?

And is it not very popular to upgrade the carb? Any reccommendations? I've heard so many good things about the sito plus, and was wondering what is a really nice/popular carb to get some more power?

Finally...what about air filters? I figure if I'm boosting the output with a pipe, the air intake needs some compensation as well?

Thanks SO much in advance and for all the help thus far!

Y'know, this is a slippery slope... the pipe is never enough.

Yes, it's common to upgrade the carb to a 24/24 model... I'll leave the E/G/Vortex debate for you to search at StellaSpeed. As for air filters, there a bunch of folks who went to Unifilters; some have switched back. I'm kinda non-plussed by the whole thing as my Sito (w/ a 102 jet and some careful tweaking of the stock setup) is getting me more than ample 'jump' off the line and an honest 60mph too.

I'll wait for something to break before I start replacing anything else.

I have been thinking of going to the sito+ on my '05 px150SA. Can any body who has done this mod. advise on jet size @ sea level ? I generally don't like to "fix what ain't broke", but could use a little more SNAP. I would like to keep the stock carb. and not have to do plug chops and stuff.

As far as fixing what ain't broke, the mechanic I spoke of earlier was making the point that the PXs and Stellas were so strangulated to meet pollution standards that they don't perform even as well as they ought to, much less what they could do. So putting a Sito+ on actually brings the bike closer to the levels it was designed for, not artificially restricted to.

I didn't do any plug chops or any of that stuff, I just started big and swapped out jets till I found one that didn't bog the engine, which for me was a 102 (at 1000 ft. elevation). The usual jet size people land at is a 99 or 100, but your results may vary.

(BTW, I learned all this stuff at that forum I won't mention again...)

The Sito+ is an excellent upgrade to the new PX150. It really brings the bike to life and gives it a nice Vespa-esque Pop, pop, pop. Not too loud. I send out 100 or 102 main jets with those. Usually 102s.

you might be rich at sea level with a 102...

with the stellas they come with a 94 stock...should go to a 99 or 100 with the sito+....

as for upgrades...a wiser man than me said this:

1) fast
2) reliable
3) cheap

pick any two


you can't get all three....

g

The new Series Americana PX150s come with a 98 main jet. The 102s have been working pretty well. We don't have Stellas here in California so we haven't done any tuning on them.

motorsport - once my warranty is up (in about 357 days ... i'll be coming to you for that sito plus. you said that you give 100 and 102 jets with that?

also, i've been reading up on oils...is motul what most of you px riders use? if so, I need fully synthetic, so is the 710 2T the way to go? Or should I go with another fully synthetic brand?

THANKS!!!

ACTUALLY, the sito plus looks almost identical to the stock pipe...could i get away with this and a jet swap without my dealer noticing?

put on the sito and upjet the carb.
the sito is basically a stock replacement, and with the upjet you shouldn't have any problem with warranty, really.

after the warranty is up... that's when you need a 24/24G and a malossi 166 and a pipe... and some porting, and gearing, and... yeah... you get the picture...

best,
-greasy

Warranty-wise, a lot of dealers will overlook a Sito... especially if they do the work. You ought to check on it first.

There's also a school of thought that you should wait till you're break-in is done before making mods... though again, the Sito is so close to stock that that may not be a real concern. I sure like mine, don't know how I rode without it.

I seem to think the 150PX has less barrel ports than the stella.

It does have 5 ports versus three ports. In theory, that would lead to a bigger main jet. So would the reed valve in the Stella. For some reason, it still uses a smaller main. Hmmm....

I have a '05 px150 with a polini 177cc kit, rejetted 24/24 carb, sito plus

It is pretty quick, and much funner to ride...

so i bought the sito plus, and i guess motorsport was out of 102 main jets, so i have a 100 on there now. do you guys think i should hold off on riding the new pipe until i get a 102, or is the 100 okay on there? i'm worried about running too lean, especially with under 300 miles on it...

pop in the 100 and ride it around the 'hood and see how it feels.
check the plug after 15~20mins of riding.

if the plug looks acceptable, then take it out and run a plug chop.

in the immortal words of my boss: "rev her up hot and see how she feels. listen closely, she's talking to ya. she'll tell ya what she wants."

just remember, two fingers on the clutch lever ready to pull-- just in case.

best,
-greasy

The 100 might be alright, but I'd feel better if you were running a bit richer... there are other sources for jets if Motorsports is out... Scooter Parts Direct, Scooterworks, Scomo, ASC. I know SPD will ship jets in a standard envelope so the shipping is minimal. Jets are cheap. Get a few and experiment.