optimizing power with the correct carb
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Enthusiast
'81 Vespa P200e, '85 Vespa PX125e, '70 Vespa 90 basketcase
Joined: 11 Jun 2020
Posts: 79
Location: St. Catharines, Ontario
Fri Jan 01, 2021 8:14 am quote
Happy New Year Scooterists.

As I am freezing my butt off here and my scooter is sitting in the garage, i was wondering if I have the right carb in my newly built px125e with a dr180 cylinder and sito plus pipe. The cylinder has less than 300 km on it. I dont feel that the carb is dialed in properly yet. I still need to run it and set it up a bit better.

Currently I am have a 24mm spacco carb in there with a 118 main jet.
I am wondering if the stock 20mm dellorto carb with upjetting and properly setting the idle and mixture screws will give me ideal and maximum performance that is destined for that scooter vs the larger 24mm carb.

any thoughts? I have read that folks here use either carb but i am wondering what is the best carb for the set up I have?

Thanks for your responses.

N
Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 & 96 Elite 80s, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 3940
Location: Oceanside, CA
Fri Jan 01, 2021 9:23 am quote
Did you open up the air box to match a 24/24 carb? If not, go down to your 20/20 carb and start with a 160/BE3/125 main jet. Plug chop and ride it and see if you can clean it up from there.
Enthusiast
'81 Vespa P200e, '85 Vespa PX125e, '70 Vespa 90 basketcase
Joined: 11 Jun 2020
Posts: 79
Location: St. Catharines, Ontario
Fri Jan 01, 2021 9:42 am quote
MJRally wrote:
Did you open up the air box to match a 24/24 carb? If not, go down to your 20/20 carb and start with a 160/BE3/125 main jet. Plug chop and ride it and see if you can clean it up from there.
No I didnít match the box to the carb. Didnít know you had to.
I can swap back to the 20mm and I may have a 125 main jet.

I guess Iíll go from there. Dial it in and see.

If this what you have done in the past?
Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 & 96 Elite 80s, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 3940
Location: Oceanside, CA
Fri Jan 01, 2021 10:04 am quote
Yep. Thatís what I did for my Malossi 166 and my friends Pinasco 177. I donít remember what we settled at but itís something in the vicinity.

If you sputter a little too much in first gear but 2,3 and 4th rev out clean, try a BE4 mixer tube.
Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1661
Location: Rochester, Minnesota
Fri Jan 01, 2021 11:14 am quote
Nelluch125 wrote:
MJRally wrote:
Did you open up the air box to match a 24/24 carb? If not, go down to your 20/20 carb and start with a 160/BE3/125 main jet. Plug chop and ride it and see if you can clean it up from there.
No I didnít match the box to the carb. Didnít know you had to.
I can swap back to the 20mm and I may have a 125 main jet.

I guess Iíll go from there. Dial it in and see.

If this what you have done in the past?
Unless someone opened up the carburetor box before you, the hole in the carburetor box is smaller than 24mm. If you pull off the air cleaner, look into the carburetor throat and pull the throttle to wide open you'll most likely see the edges of the carburetor box.
Enthusiast
1959 Allstate w P125x Engine
Joined: 29 Nov 2020
Posts: 72
Location: Los Angeles
Sun Apr 04, 2021 12:04 pm quote
Is this what you mean? From this picture of mine the space between those circles is not more than 1mm. There is a gap there, though. Previous owner was billed for porting.
Have an idea. Maybe you guys can let me know what you think..
Thinking of getting a 20/20 carb for city driving, and switching back to the 24 for touring. Each with its own jetting configuration.[/quote]



Hooked
PX
Joined: 28 May 2020
Posts: 125
Location: Bognor Regis
Mon Apr 05, 2021 6:20 am quote
When you get your 24mm about right can you post on here the jet stack values you are using. I'm in another thread where I'm currently in similar predicament. I've been given excellent advice on what to do but would like to compare your values. What pilot jet you running too.? I've got a road 2 so pretty similar to the sito plus. Thanks
Molto Verboso
2007 Stella 225
Joined: 02 Nov 2019
Posts: 1661
Location: Rochester, Minnesota
Mon Apr 05, 2021 4:08 pm quote
Ray8 wrote:
Is this what you mean? From this picture of mine the space between those circles is not more than 1mm. There is a gap there, though. Previous owner was billed for porting.
Have an idea. Maybe you guys can let me know what you think..
Thinking of getting a 20/20 carb for city driving, and switching back to the 24 for touring. Each with its own jetting configuration.
[/quote]

Hard for me to make out what you habe circles on in that picture. Have a look at this topic. Has a few pictures with port matching a 24/24


P200 Swapping 20/20 for 24/24

20/20 Carb in a P200e?????!!!!!!
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