V-Boost System - Yamaha VMX12H Supplementary Service Manual

V-BOOST SYSTEM

0°
7-61
180° 360°
180° ± 70'°
V-BOOST SYSTEM
Description
The V-Boost consists of a servomotor, a control
cable, special intake joints and butterfly valves.
The front and rear cylinders are connected by
the special intake joint. In the middle of the
intake joint is the butterfly valve.
The butterfly valve is opened and closed by the
servomotor. And this valve is securely closed
by means of i t s return spring.
The servomotor senses rpm from engine's
ignition signals and controls the butterfly valve
operation. The butterfly valve begins to open a t
approximately 6,000 r/min and fully opens at
approximately 8,000 r/min.
For example, while the #1 cylinder is in the
#2
intake stroke, the cylinder is in the com-
bustion storke and consequently the
a t rest. I f the butterfly valve opens in this state,
an air fuel mixture flows into the #1 cylinder
#2
through the #1 and
charger system).
This results in an increased intake efficiency per
cylinder, leading to higher performance.
CYLINDER
COMBUSTION
C EXHAUST
D INTAKE
E COMPRESSION
540°
1 1 0 °
#2
carb is
carbs (as in the super-
720° 900°