BoonDocker YAMAHA WR-F: WR450F Box - Manual (Page 9)

Boost Solenoid Installation
Install the boost solenoid in a pressure line between the air box (or charge tube) and wastegate
actuator. Attach the metal port of the solenoid with a 3/16” hose to the air box (or charge tube) fitting
(see the figure below). Connect the right-angle port of the solenoid with a 3/16” hose to the wastegate
actuator. Attach a short length of hose to the third port and point it downward so that it won’t get
water in it. This is the actuator vent hose. Attach the solenoid so that it is supported. Use small zip ties
to secure the hoses to the ports.