Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Normal
Bigger ports mean less vacuum, so need more taper on the needles. Fuel enters the inlet tract because of the pressure differential above and below the jets. With big ports the differential is less, so to get the fuel/air mixture at optimum, bigger jetting is needed. Bigger ports suit higher rev ranges at the expense of lower revs. At high revs there is more vacuum. 500cc Manx Nortons have a huge venturi - a 500 cc single with smaller venturi can beat them in tight circuits, if a similar frame and gearbox is used.The Manx was developed for the IOM TT.
Bigger ports mean less vacuum, so need more taper on the needles. Fuel enters the inlet tract because of the pressure differential above and below the jets. With big ports the differential is less, so to get the fuel/air mixture at optimum, bigger jetting is needed. Bigger ports suit higher rev ranges at the expense of lower revs. At high revs there is more vacuum. 500cc Manx Nortons have a huge venturi - a 500 cc single with smaller venturi can beat them in tight circuits, if a similar frame and gearbox is used.
The Manx was developed for the IOM TT.
