5-12 ENGINE TOP END
Clean Air System
Vacuum Switch Valve Installation
Install the vacuum switch valve so that the air duct [A]
faces right side.
Route the hoses correctly (see Cable, Wire, and Hose
Routing section in the Appendix chapter).
Vacuum Switch Valve Test
Vacuum Switch Valve (see Vacuum Switch Valve Re-
moval in this chapter)
Connect a vacuum gauge [A] and syringe [B] or fork oil
level gauge to the vacuum hoses as shown.
Special Tool - Fork Oil Level Gauge: 57001-1290
Air Flow [C]
Gradually raise the vacuum (lower the pressure) applied
to the vacuum switch valve, and check the valve opera-
tion. When the vacuum is low, the vacuum switch valve
should permit air to flow. When the vacuum raises to
valve closing pressure, it should stop air flow.
Low Vacuum [D]
Secondary Air Flow [E]
If the vacuum switch valve does not operate as described,
replace it with a new one.
To check air flow through the vacuum switch valve, just
blow through the air cleaner hose.
Vacuum Switch Valve Closing Pressure (Open → Close)
Standard: 41 ∼ 49 kPa (310 ∼ 370 mmHg)
High Vacuum [A]
Secondary air cannot flow [B]
Clean Air System Hose Inspection
Be certain that all the hoses are routed without being flat-
tened or kinked, and are connected correctly to the air
cleaner housing, throttle body, vacuum switch valve and
air suction valve covers.
If they are not, correct them. Replace them if they are