OP
UTC

Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 362
Location: St. Catharines, Ontario
 
Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 362
Location: St. Catharines, Ontario
UTC quote
Hey All,

Just wondering if someone can walk me through the steps of gasket matching a 24mm carb to the 20mm air box?

Looking for detailed steps and visuals (if possible) on how to perform this modification correctly.

This may be a final ace in dialing in my scoot.

Looking forward to learning more.
Thank you.

N
@socalguy avatar
UTC

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7155
Location: So Cal
 
bodgemaster
@socalguy avatar
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7155
Location: So Cal
UTC quote
There's not too much to it.

As you can see from the pic, the openings between the carb, carb box and inlet are a bit different as they come from the factory.

The object is to match the openings and create an unobstructed flow of the air-fuel mixture from the carb into the crankcase.

Start by marking the openings. Using a rotary tool and sanding wheel *carefully* grind the box to match the carb. Be *extra careful* grinding the opening on the case, because if you take off too much material you'll ruin the sealing surface and introduce an air leak.


External inline image provided by member with no explanatory text
@sdjohn avatar
UTC

Johnny Two Tone
'15 GTS300, '86 PX125EFL, '66 VBB, '01 ET4
Joined: UTC
Posts: 8511
Location: San Diego, CA
 
Johnny Two Tone
@sdjohn avatar
'15 GTS300, '86 PX125EFL, '66 VBB, '01 ET4
Joined: UTC
Posts: 8511
Location: San Diego, CA
UTC quote
on the case side you can blend at the top and let the lower part of the opening remain untouched. if you start to go too nuts you will hit the stud opening on the back side. It's easiest done with the engine split, of course, otherwise hard to keep material from entering the engine and trashing your bearings, etc.
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9841
Location: Nashville

48 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9841
Location: Nashville

48 Days Since Last Explosion
UTC quote
Also, if you have the cases split, you can trace/score the base of the carb into the airbox, then bolt the airbox to the case and do the whole thing as a single unit to get the matching really nice.
@scooterist avatar
UTC

Molto Verboso
71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
Joined: UTC
Posts: 1553
Location: Tucson, AZ
 
Molto Verboso
@scooterist avatar
71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
Joined: UTC
Posts: 1553
Location: Tucson, AZ
UTC quote
I have done it once or twice. I did a 26mm carb in one of the P and a 24 mm on another P. It was fairly easy from what I remember, just remove the carb box, enlarge the gasket and also enlarge the intake reed.

It is your choice of using a file or a dremel, the end result is the same, just make sure you stuff a small rag inside the engine case reed and vacuum it of blow it after you are done. in reality there is no mystery to it. As long as the engine case opening is at least the diameter of the carburator Venturi you are good to go, if the engine case reed opening is smaller than the Venturi of the carburator then you accomplished nothing. Good luck!
OP
UTC

Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 362
Location: St. Catharines, Ontario
 
Hooked
'81 Vespa P200e, '85 Vespa PX125e, 1985 T5
Joined: UTC
Posts: 362
Location: St. Catharines, Ontario
UTC quote
Thanks everyone.

As opposed to dremmeling and matching, would an alternative be to simply purchase a carb box for a p2 and mount that on my 125 cases?

Thanks for all of your helpful responses.
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9841
Location: Nashville

48 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9841
Location: Nashville

48 Days Since Last Explosion
UTC quote
Not necessarily. Even with the 24mm carb box on my P200 motor, I had to do a moderate amount of port matching to open it up.

The ideal way to do it is with a Dremel or other rotary tool. Start with grinding bits, then move to sanding drums once you get close.

The bits & drums are cheap. I get mine off Amazon for maybe $10/set and they last damn near forever, it seems like.
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: 0.0129s ][ Queries: 4 (0.0050s) ][ live ][ 313 ][ ThingOne ]