Hi Mark,
The manual tap is really a reserve tap, if you run all the time with the manual on (lever vertical) then when the bike starts to splutter and run out of fuel, you really have run out

get ready to push.
There are photos showing the internals of the electric tap here
http://www.morini-riders-club.com/thebi ... rotap.html
When the petrol level drops below the height of the plastic tube inside the filter then you need to open the manual tap, which has a similar but shorter plastic tube.
But opening both really does help when you are running at full throttle - A Tutto Gas.
Steve [/url]