Subaru Robin EX30 - Manual (Page 51)

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11-1 FUNCTIONS AND CONSTRUCTION
EX series engines employ an automatic decompression system as a standard feature. This enables easy starting
of the engine, with lighter recoil pull.
The automatic decompression system releases the compression of the engine by lifting up the exhaust valve at
cranking speed. The following is the explanation of the function.
At the end of the compression process, the release lever lifts up the rocker arm (exhaust) which in turn opens up
the exhaust valve slightly to release the compression.
The release lever has a fl yweight on its end and another end of the lever is a crescent cam.
When the engine is cranked, the crescent cam projects above the cam profi le and lifts up the rocker arm (exhaust)
because the force of the return spring on the weight is larger than the centrifugal force on the weight.
11. AUTOMATIC DECOMPRESSION SYSTEM
When the cranking speed reaches a specifi ed r.p.m., the crescent cam is retracted under the cam profi le because
the centrifugal force applied to the fl yweight becomes larger than the force of the return spring on the weight and
thus it is shifted to the position shown in the illustration below.
11-2 INSPECTION
When assembling the release lever, make sure that it works smoothly.
A
ROCKER ARM
(EXHAUST)
ROCKER ARM
(EXHAUST)
ROCKER ARM
(INTAKE)
CAM
CRESCENT CAM
RELEASE LEVER CAMSHAFT
RELEASE LEVER
DETAIL
A
A
RELEASE LEVER
ROCKER ARM
(EXHAUST)
ROCKER ARM
(INTAKE)
CAM
CRESCENT CAM
ROCKER ARM
(EXHAUST)
CAMSHAFT
RELEASE LEVER
DETAIL
A