Honda VFR800F 2014 Service Manual page 188

CYLINDER HEADruALVES
TROUBLESHOOTING
'
Engine top-end problems usually affect engine performance. These problem can be diagnosed
by
a
compression test or
by
tracing engine noises to the top-end with
a
sounding
rod or stethoscope.
'
If
the performance is poor
at low speeds,
check for white smoke
in the crankcase breather hose. lf
the hose
is smoky, check for
a seized piston ring (page
13-14).
Compression too low,
hard
starting or poor performance
at low
speed
.
Valves:
-
Incorreci valve clearance adjustment
-
Burned or bent valve
-
Incorrect valve timing
-
Broken valve
spring
-
Uneven valve seating
.
Cylinder
head:
-
Leaking or damaged
cylinder head gasket
-
Warped or
cracked cylinder head
-
Loose spark plug
.
Worn cylinder, piston,
or piston rings (page
13-14)
Compression too high, overheating or knocking
'
Excessive carbon build-up on piston crown or on combustion chamber
Excessive smoke
.
Cylinder head:
-
Worn valve
stem or valve guide
-
Damaged stem seal
.
Worn cylinder, piston,
or piston rings (page
13-14)
Excessive noise
.
Cylinder head:
-
lncorrect valve
clearance adjustment
-
Sticking valve
or broken valve spring
-
Damaged
orworn
camshaft
-
Loose or worn
cam chain
-
Worn or damaged cam chain
-
Worn or damaged cam chain
tensioner
-
Worn cam sprocket teeth
.
Worn cylinder, piston,
or
piston rings
(page
13-14)
Rough idle
.
Low cylinder compression
10-4