OP
@astromags avatar
UTC

Veni, Vidi, Posti
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
 
Veni, Vidi, Posti
@astromags avatar
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
UTC quote
This is on my VBA

I had an occasional problem that has become more common.

Sometimes after riding and mostly when the scooter is still warm, when I go to start it it won't start. If I remove the air box lid, it will fire right up every time. I cleaned the filter thinking it was clogged, even though it has only a few hundred miles on it and looked almost good as new.

The past couple of times it happened it would start without the lid on, but it would struggle to run, I would have it at full throttle and it would just be barely running and putt putt and sputter. Eventually it sped up and ran.

The last time it happened, i took the lid off, it was sputtering and barely running, so I decided I'd remove the air filter and see what happened. As soon as I unscrewed the "weird fat barrel-looking screw" at the back of the air filter, it started revving right up.

Anyway, now it pretty much won't start at all with that screw in and the filter box lid on.

It seems that somehow I'm not getting enough air into the carb, even though the filter is clean. I started looking for an air leak but don't see any evidence of one.

So what's going on? Where should I be looking?
@socalguy avatar
UTC

bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7070
Location: So Cal
 
bodgemaster
@socalguy avatar
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
Joined: UTC
Posts: 7070
Location: So Cal
UTC quote
Is the filter blocking the air corrector hole?

What happens when you put just the mounting screw in, without the filter?
OP
@astromags avatar
UTC

Veni, Vidi, Posti
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
 
Veni, Vidi, Posti
@astromags avatar
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
UTC quote
SoCalGuy wrote:
Is the filter blocking the air corrector hole?

What happens when you put just the mounting screw in, without the filter?
Didn't think of that. I'll take a closer look and see if it's not fitting correctly.
@ginch avatar
UTC

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8595
Location: Victoria, Australia
 
Veni, Vidi, Posti
@ginch avatar
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8595
Location: Victoria, Australia
UTC quote
Re: Need air can't breathe...
astromags wrote:
I would have it at full throttle and it would just be barely running and putt putt and sputter. Eventually it sped up and ran.
Happened to me exactly like this with the last carb I had on. To get it to re-start hot, I would turn the fuel tap off, let it run for half a minute then kill it. Or let it run right out. Then it would start fine. Or, if I forgot to let it run out, I'd turn the tap off, keep kicking until it started and then when it began to run out of fuel it would race and I could turn the tap on.

So obviously that's a flooding issue, even though the needle and seat looked fine and would work outside of the carb as well. Also swapped needle & seats as well. Doesn't seem to happen with the Vortex I have on there now.
OP
@astromags avatar
UTC

Veni, Vidi, Posti
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
 
Veni, Vidi, Posti
@astromags avatar
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
UTC quote
Re: Need air can't breathe...
Ginch wrote:
astromags wrote:
I would have it at full throttle and it would just be barely running and putt putt and sputter. Eventually it sped up and ran.
Happened to me exactly like this with the last carb I had on. To get it to re-start hot, I would turn the fuel tap off, let it run for half a minute then kill it. Or let it run right out. Then it would start fine. Or, if I forgot to let it run out, I'd turn the tap off, keep kicking until it started and then when it began to run out of fuel it would race and I could turn the tap on.

So obviously that's a flooding issue, even though the needle and seat looked fine and would work outside of the carb as well. Also swapped needle & seats as well. Doesn't seem to happen with the Vortex I have on there now.
You may be right. Maybe the lack of air is really too much fuel. I do have a bad needle valve, and possibly a bad fuel tap. I've been turning it off to keep fuel from ending up on the ground, but now I'm getting it even with the tap off.

Well, I have carb issues in general. After all this I was inspecting it and the fuel seems to be leaking from around the cap of the float chamber, and I just went to tighten it, I'm pretty sure I over-tightened and stripped it... I may have just compressed the cap, but am afraid to keep turning the screw.

Anyone have a good 20/20 SI Carb they want to let go of?
@primavera130 avatar
UTC

Hooked
Vespa P200, Primavera 130, VNA200, Italjet Pack-a-Way Moped, Ciao etc
Joined: UTC
Posts: 322
Location: Humboldt County, California
 
Hooked
@primavera130 avatar
Vespa P200, Primavera 130, VNA200, Italjet Pack-a-Way Moped, Ciao etc
Joined: UTC
Posts: 322
Location: Humboldt County, California
UTC quote
Re: Need air can't breathe...
I was going to say the float bowl top or flooding. It seems like you are dealing with both. If you think you are going to keep that carb, you can drill and tap the next bigger size threads. I had to after my 24-24 kept vibrating the float bowl bolts loose/. The threads had just gotten hogged out.
astromags wrote:
Ginch wrote:
astromags wrote:
I would have it at full throttle and it would just be barely running and putt putt and sputter. Eventually it sped up and ran.
Happened to me exactly like this with the last carb I had on. To get it to re-start hot, I would turn the fuel tap off, let it run for half a minute then kill it. Or let it run right out. Then it would start fine. Or, if I forgot to let it run out, I'd turn the tap off, keep kicking until it started and then when it began to run out of fuel it would race and I could turn the tap on.

So obviously that's a flooding issue, even though the needle and seat looked fine and would work outside of the carb as well. Also swapped needle & seats as well. Doesn't seem to happen with the Vortex I have on there now.
You may be right. Maybe the lack of air is really too much fuel. I do have a bad needle valve, and possibly a bad fuel tap. I've been turning it off to keep fuel from ending up on the ground, but now I'm getting it even with the tap off.

Well, I have carb issues in general. After all this I was inspecting it and the fuel seems to be leaking from around the cap of the float chamber, and I just went to tighten it, I'm pretty sure I over-tightened and stripped it... I may have just compressed the cap, but am afraid to keep turning the screw.

Anyone have a good 20/20 SI Carb they want to let go of?
OP
@astromags avatar
UTC

Veni, Vidi, Posti
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
 
Veni, Vidi, Posti
@astromags avatar
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
UTC quote
I have another buggered up carb. I may be abke to switch fliat biwl caos. The current one looks smashed. I may try re tapping first.
OP
@astromags avatar
UTC

Veni, Vidi, Posti
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
 
Veni, Vidi, Posti
@astromags avatar
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
UTC quote
Ok. Its definitely stripped.

I just took the screw for the float bowl cap from the old 24/24 carb. It has a longer screw but the threads seem different. Its holding for now.

Does anyone know if the top half of the 24/24 float assembly will work on a 20/20 carb?
@vader19 avatar
UTC

Mr. Clean
P,SUPER,V90, 50 Special
Joined: UTC
Posts: 10205
Location: This is't my locker!
 
Mr. Clean
@vader19 avatar
P,SUPER,V90, 50 Special
Joined: UTC
Posts: 10205
Location: This is't my locker!
UTC quote
^^ I do believe it will
@bobo avatar
UTC

Ossessionato
'70 Super 150, Medley 150S, '23 Ducati Monster SP
Joined: UTC
Posts: 2533
Location: Sydney, Australia
 
Ossessionato
@bobo avatar
'70 Super 150, Medley 150S, '23 Ducati Monster SP
Joined: UTC
Posts: 2533
Location: Sydney, Australia
UTC quote
Astro I just replaced my float chamber cover. I'd stripped mine at the banjo. A new cover is pretty cheap. The gaskets were in pretty bad shape too. My scoot was racing at idle and I assume that was the cause.
@killo avatar
UTC

Ossessionato
I have a few scooters....
Joined: UTC
Posts: 2225
Location: San Antonio, TX
 
Ossessionato
@killo avatar
I have a few scooters....
Joined: UTC
Posts: 2225
Location: San Antonio, TX
UTC quote
I replaced a fuel tap on my VNB years ago. The new tap had the vent tube bent at about a 45 degree angle. When I filled the tank, fuel would flow down the vent tube into the carb, even though the fuel tap was off. Combine that with a leaky float valve and you've got a flooded carb every time you turn off the engine even if you turn off the tap.

For me, I bent the vent tube straight up until it nearly touched the top of the tank. Problem solved.
OP
@astromags avatar
UTC

Veni, Vidi, Posti
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
 
Veni, Vidi, Posti
@astromags avatar
'80 P200E, '76 Primavera 125 ET3. '59 Vespa 150
Joined: UTC
Posts: 6897
Location: GT, Texas
UTC quote
Yep. This all sounds like what I'm dealing with. My fuel tap is new, but a rebuild combining parts from two new but broken ones. That and a float needle that wont seat.

Thanks for the info.
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