OP
@jonny_ray avatar
UTC

Enthusiast
Vespa PX125
Joined: UTC
Posts: 58
Location: South Wales
 
Enthusiast
@jonny_ray avatar
Vespa PX125
Joined: UTC
Posts: 58
Location: South Wales
UTC quote
Hi I have a Vespa PX125 2016 70th anniversary edition and I am thinking of buying a Zeus CDI. Apart from a Sip 2 racing exhaust it is completely stock. My question is I know that I will have to upjet the carburetor but could somebody please help me out on the size of the main jet and is it a push on jet or a screw in? Any advice would be much appreciated. Would I have to upjet the other jets too? Thanks for taking the time to read this and I hope someone could help me out. Cheers.
My pride and joy. I love my Vespa more than the missus.
My pride and joy. I love my Vespa more than the missus.
@birdsnest avatar
UTC

Not So Moderator
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
 
Not So Moderator
@birdsnest avatar
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
UTC quote
Jonny Ray wrote:
Hi I have a Vespa PX125 2016 70th anniversary edition and I am thinking of buying a Zeus CDI. Apart from a Sip 2 racing exhaust it is completely stock. My question is I know that I will have to upjet the carburetor but could somebody please help me out on the size of the main jet and is it a push on jet or a screw in? Any advice would be much appreciated. Would I have to upjet the other jets too? Thanks for taking the time to read this and I hope someone could help me out. Cheers.
Cheers!

Good looking scoot! I don't know the zeus so can't comment there... As far as your main jet goes, you *should* be able to change the main jet without messing with the rest of the stack.

It is just the tip….(ahem)…. And it's easy to pull off. Just unscrew the main stack from the carby first. IIRC, Stock main is a 100, so I would order 3 jets. A 106, 104, and a 102.

Start with the 106 and work down until it doesn't feel boggy. Smart money is the 104 will be the winner.

YMMV
UTC

Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
 
Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
UTC quote
Birdsnest wrote:
Cheers!

Good looking scoot! I don't know the zeus so can't comment there... As far as your main jet goes, you *should* be able to change the main jet without messing with the rest of the stack.

It is just the tip….(ahem)…. And it's easy to pull off. Just unscrew the main stack from the carby first. IIRC, Stock main is a 100, so I would order 3 jets. A 106, 104, and a 102.

Start with the 106 and work down until it doesn't feel boggy. Smart money is the 104 will be the winner.

YMMV
Normally UK PX are 96 stock. So Birdsnest advice is sound and hes bang on with calculation of 4+ over stock jet, accept i wouldnt get a 106 it will be way too big. Real Delorto jets are getting pricy now, £6-7 a pop, so you can save a few quid. If you are just doing the pipe, then 4 over standard at 100, if you are going to get the drilled filter then 101/102. I know so many people who run what you have, i have done so myself on my current scoot that was a px125 (now 177) and this jetting is always correct.
As to the zeus, are you sure you really need it? I guess you are doing this to get over the RPM restrictor, but quite frankly you are very unlikely to hit more than 6200 RPM on what you got. I think on the restrictor it starts to plummet way over 6200! Something like 7k. Pop you big jet stack off from under your air filter, get a magnifying glass or use your phone magnifyer and read the number. If it says 96 then do what Birdsnest says, get a 100/102, id be tempted to stay with the 102 for the cold weather and the 100 for the hot. You can get a 101 which is what I ran with the same rig as a compromise balance between seasons. You should really take advantage of the massive 0.5bhp increase with a drilled filter, in which case put in a 102 if you do this. As the px125 is low HP anyway, a 0.5 bhp gain for using a drill is cheap bang for no bucks.
@birdsnest avatar
UTC

Not So Moderator
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
 
Not So Moderator
@birdsnest avatar
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
UTC quote
Thanks for correcting me on the PX main size! Should have looked it up before posting.
UTC

Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
 
Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
UTC quote
Birdsnest wrote:
Thanks for correcting me on the PX main size! Should have looked it up before posting.
Yes but you're right , 4 pts over, I do know the jet stack varies outside the uk though .
@birdsnest avatar
UTC

Not So Moderator
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
 
Not So Moderator
@birdsnest avatar
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
UTC quote
Well... even if I looked it up I would have gotten it wrong. :-/
Looks like the old (early 80's) P and PX125s were 99/100.

https://scooterhelp.com/scooters/VNX2T.px125e.html

I bet they reduced it due to emissions in later years?
UTC

Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
 
Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
UTC quote
Birdsnest wrote:
Well... even if I looked it up I would have gotten it wrong. :-/
Looks like the old (early 80's) P and PX125s were 99/100.

https://scooterhelp.com/scooters/VNX2T.px125e.html

I bet they reduced it due to emissions in later years?
Yep, over here with have all the Euro III, IV, i think we are heading for Euro 6 emissions and safety regs. The PX200 of course was killed off by Euro III, then just the 125 left, leaned up even further, then catalytic converters. At one point they were talking about riders having to have air bag trousers!!! Imagine that on your vespa, a nice jaunt along the seafront in the sun with freaking airbag trousers on. Tightened Euro laws probably the downfall of LML Scooters as ABS dual braking laws came in, etc.

https://www.visordown.com/news/product-news/airbag-motorcycle-trousers-are-now-thing-apparently
@birdsnest avatar
UTC

Not So Moderator
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
 
Not So Moderator
@birdsnest avatar
VNB VSC VMA VSX - o9c vbc vmb
Joined: UTC
Posts: 8262
Location: Hustletown, TX
UTC quote
*laughs/shakeshead*
"Air bag trousers"
UTC

Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
 
Addicted
Joined: UTC
Posts: 937
Location: Planet Earth
UTC quote
Birdsnest wrote:
*laughs/shakeshead*
"Air bag trousers"
Yes , it's all true. With my cynical head on and likely truth you think that the euro politicians invent a law like this to push through their own interests in manufacturers to make the new requirements and they own shares in them. Can't be true can it, corruption like that ? Ummm I wonder https://www.wantedineurope.com/news/the-european-union-invests-in-airbag-jeans.html
OP
@jonny_ray avatar
UTC

Enthusiast
Vespa PX125
Joined: UTC
Posts: 58
Location: South Wales
 
Enthusiast
@jonny_ray avatar
Vespa PX125
Joined: UTC
Posts: 58
Location: South Wales
UTC quote
Thanks for the replies much appreciated.
DoubleGood Design banner

Modern Vespa is the premier site for modern Vespa and Piaggio scooters. Vespa GTS300, GTS250, GTV, GT200, LX150, LXS, ET4, ET2, MP3, Fuoco, Elettrica and more.

Buy Me A Coffee
 

Shop on Amazon with Modern Vespa

Modern Vespa is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com


All Content Copyright 2005-2024 by Modern Vespa.
All Rights Reserved.


[ Time: 0.0180s ][ Queries: 4 (0.0068s) ][ live ][ 313 ][ ThingOne ]