Why do they have it and not a normal gravity fed fuel tap?

What does it do different and how does it work?

As far as I know it doesn't have a fuel pump and is just a normal carbed bike

Edited August 9, 20179 yr by johnnyboxer

5 minutes ago, oni nou said:

Probably to stop it suffering the same problems that the Rev3 had and causing it to be a pain to start.

In what way, do you know how it works?

Did the REV 4T have problems starting?

No problems starting Beta 4t Rev4 or Evo.  You could replace the electric tap with a standard item. Thread pitch is 10mm x 1.00 The only reason I could see doing this is that the stock tap quit working and they are fairly expensive.

If a carb floods on a 4 stroke and depending upon the state of the inlet valves (fully closed or partially open), and depending upon the inclination of the carb relative to the inlet manifold (eg when you've fallen off the carb may well be uphill of the inlet manifold) it is quite possible that fuel can leak into the cylinder.  This can give rise to two problems.  Fuel leaking past the rings to contaminate the lubricating oil, or possibly even accumulating in the cylinder and causing a hydraulic lock where the engine won't turn over but excess pressure on the kickstart could lead to a bent con rod.

A solenoid operated fuel tap overcomes either possibility because, as oni nou says, it shuts off when the engine stops.

I know all the old 4 strokes had normal fuel taps but I doubt if they had made a solenoid version back then they would have been very reliable!