Vespa Reed Valve Fuel Pump
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- registered user
- Posts: 4
- Joined: Wed Sep 25, 2013 8:15 pm
- Main scooter: Vespa Gl VLA1T T5 188cc
- Location: Finland
- Contact:
Here's my setup if that helps you..
Schematic installation picture (source: GSF)

Vacuum connection on my MMW2 membrane:

Mikuni vacuum pump connection in my case:

- blue arrow = vacuum connection from the membrane
- yellow arrow = return line to the tank (I have a banjo attached next to fuel cap on top of the tank. Mikuni SI main jet inside the return pipe restricting the flow)
- purple arrow = Y-connection
- red arrow = fuel line to carb
- green line = line from the tank (hi-flow tap in the tank)
Also required:
- Mikuni TMX35: smaller float needle valve needs to be fitted. Otherwise it will flood because the bigger original needle cannot take the pressure. I don't know what is the case with Dellorto.
- fuel tap breather pipe which is inside the tank needs to be plugged when fuel pump in use
- buffer rubber between the pump and frame/casing etc. is recommended
Schematic installation picture (source: GSF)

Vacuum connection on my MMW2 membrane:
Mikuni vacuum pump connection in my case:

- blue arrow = vacuum connection from the membrane
- yellow arrow = return line to the tank (I have a banjo attached next to fuel cap on top of the tank. Mikuni SI main jet inside the return pipe restricting the flow)
- purple arrow = Y-connection
- red arrow = fuel line to carb
- green line = line from the tank (hi-flow tap in the tank)
Also required:
- Mikuni TMX35: smaller float needle valve needs to be fitted. Otherwise it will flood because the bigger original needle cannot take the pressure. I don't know what is the case with Dellorto.
- fuel tap breather pipe which is inside the tank needs to be plugged when fuel pump in use
- buffer rubber between the pump and frame/casing etc. is recommended
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- Vespa Gl 188 "T5" VLA1T -65
- Vespa Rally 200 VSE1T -73
- Lammy 200dl -71
- Vespa PX200 disc racer project