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@popgunandy avatar
UTC

Hooked
61 VBB 76 Rally 200 79 P200 80 Sport 100
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Location: Folsom CA
 
Hooked
@popgunandy avatar
61 VBB 76 Rally 200 79 P200 80 Sport 100
Joined: UTC
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Location: Folsom CA
UTC quote
I've got some leakage between my airbag and carb - I've surfaced the carburetor and the bottom of the airbox and top of the cases, but I'm struggling with how to dress the surface on the inside of the box where it meets the carburetor.

What are some techniques folks have used for this area? A new airbox is a really untenable resolution given their availability and price.
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Molto Verboso
1958 Allstate 177VMC, 1962 Allstate, Yamaha Vino 70cc
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Posts: 1994
Location: Philadelphia
 
Molto Verboso
1958 Allstate 177VMC, 1962 Allstate, Yamaha Vino 70cc
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Posts: 1994
Location: Philadelphia
UTC quote
Popgunandy wrote:
I've got some leakage between my airbag and carb - I've surfaced the carburetor and the bottom of the airbox and top of the cases, but I'm struggling with how to dress the surface on the inside of the box where it meets the carburetor.

What are some techniques folks have used for this area? A new airbox is a really untenable resolution given their availability and price.
I put permatex make a gasket on my gaskets. Seals pretty well.
@gickspeed avatar
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Ossessionato
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Location: Racing Capital of the World
 
Ossessionato
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UTC quote
Popgunandy wrote:
I've got some leakage between my airbag and carb - I've surfaced the carburetor and the bottom of the airbox and top of the cases, but I'm struggling with how to dress the surface on the inside of the box where it meets the carburetor.

What are some techniques folks have used for this area? A new airbox is a really untenable resolution given their availability and price.
what do you mean by "surfaced?" Do you mean setting it up on a mill and taking a thousands off?

a decent airbox bottom is not really a lot of money and spares are not in a short supply.
OP
@popgunandy avatar
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Hooked
61 VBB 76 Rally 200 79 P200 80 Sport 100
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61 VBB 76 Rally 200 79 P200 80 Sport 100
Joined: UTC
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Location: Folsom CA
UTC quote
GickSpeed wrote:
what do you mean by "surfaced?" Do you mean setting it up on a mill and taking a thousands off?

a decent airbox bottom is not really a lot of money and spares are not in a short supply.
An airbox has two mating surfaces - one on the bottom to mount on the engine case, and one inside that mates with the carburetor. Surfacing means planing so that those surface meet flush with no leaks; sometimes the box is warped and needs to be corrected. This is relatively easy to address with respect to the engine casing, but difficult with the interior surface because of the airbox walls.

In attempting to buy a replacement, I've been hard-pressed to find one for less than $125, and equally challenged to find a P200e airbox that matches the one I have.
@v_oodoo avatar
UTC

Style Maven
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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@v_oodoo avatar
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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UTC quote
I've got a few spares, let me have a look and check for condition. Do you need an automix box for your P200 as well?
@gickspeed avatar
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Ossessionato
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Ossessionato
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UTC quote
Popgunandy wrote:
An airbox has two mating surfaces - one on the bottom to mount on the engine case, and one inside that mates with the carburetor. Surfacing means planing so that those surface meet flush with no leaks; sometimes the box is warped and needs to be corrected. This is relatively easy to address with respect to the engine casing, but difficult with the interior surface because of the airbox walls. .
Thanks. Was not aware of that.

I've set up cases on a mill and machined the gasket area for the carb as I have had interference in years past. I have also set up a p200 carb box on a mill and then machined a few thousands off the gasket surface on both sides; so it can be done.

Regardless, just buy a good used carb box bottom. You can use either p125 and p200, just transfer the injection parts.


Good luck.
⚠️ Last edited by GickSpeed on UTC; edited 1 time
OP
@popgunandy avatar
UTC

Hooked
61 VBB 76 Rally 200 79 P200 80 Sport 100
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Posts: 288
Location: Folsom CA
 
Hooked
@popgunandy avatar
61 VBB 76 Rally 200 79 P200 80 Sport 100
Joined: UTC
Posts: 288
Location: Folsom CA
UTC quote
V oodoo wrote:
I've got a few spares, let me have a look and check for condition. Do you need an automix box for your P200 as well?
Yeah - 79 P200e with autolube. Thanks!
Forum member supplied image with no explanatory text
@keaton85 avatar
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Addicted
Stella 2T, P200, Rally 180 Euro
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Addicted
@keaton85 avatar
Stella 2T, P200, Rally 180 Euro
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Location: Camden, ME
UTC quote
Hylomar Blue, put it on thin and quick. Doesnt wash away with petrol and never sets.
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Molto Verboso
71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
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Location: Tucson, AZ
 
Molto Verboso
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71' Sprint Veloce , 05' Vespa PX150, 1978 P200E
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UTC quote
My most bizarre air leak was also a rare one to t-shoot. As it turns out I had one of the hollow carburator nuts cracked with a hairline. it fooled me everytime because it had enough strength to "feel tight" but it wasn't really tightening.
I think the torque specs are like 11lb/tq(I could be wrong) but not much.

The other thing that you need to watch for is warped carburator or carb box. You can remedy this by using a 1500-4000 sand grid and a mirror or glass and start sanding it until the surface appears flat. Other than that there is not much of a mystery or science behind it.

Needless to say look for any signs of stripped studs, hollow nuts and OHHH yeah, the proper size of studs. I paid a "mechanic" a few years back to do a engine swap and some how I also ended up with shorted carburator studs, that would also do it!! Facepalm emoticon
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'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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UTC quote
I'd recommend using one of the premium blue gaskets that are a bit thicker and seal better than stock paper ones do here with just two bolts.

https://www.sip-scootershop.com/en/product/gasket-sip-carburettor-casing-carburettor-premium_92976030
Quote:
While almost all Vespa engine parts have been improved and updated over the years, the gaskets have regrettably been forgotten. To eliminate this deficit, we have had the SIP PREMIUM gasket sets produced by an experienced Italian gasket manufacturer, replacing all previously paper made gaskets with items made of a tough Aramid fibre. This material is an asbestos-free mixture of cellulose and synthetic fibres and provides extremely effective sealing properties.
(PS still looking for spare oil injector airbox )
.
this is the one from SIP
this is the one from SIP
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Banned
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Location: Brea, CA
 
Banned
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UTC quote
Just make it neat and clean.
@garncarz avatar
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Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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Molto Verboso
@garncarz avatar
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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Location: York, PA (the intellectual center of the universe)
UTC quote
GickSpeed wrote:
Thanks. Was not aware of that.
ROFL emoticon
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Ossessionato
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Location: northern New York
 
Ossessionato
@orwell84 avatar
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UTC quote
garncarz wrote:
ROFL emoticon
I don't think he meant to take Mr. Gick to school…
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