3 main reasons:

1. a v-twin engine needs clean and proper air to run! not air with oil-vapor! cuts down bhp...

2. take a look at the underside of the airfilter-housing. there is a intake-screw (inside the rubber pipe) with a very smal valve on it . this valve is so small (0.9mm), the air is mostly being blocked from escaping freely out of the cylinder and crank house. it's like a traffic jam....4 lanes coming into one lane.

3. a air filter has to be dry

conclusion:
clean the air this engine is breathing and enable the leaving air underneath the pistons to escape!

sory, but my technical english is not perfect.

Last edited by swissghost; 23/05/14 08:43 PM.