URAL Motorcycles 2000 -10 series, Repair Manual, Page: 26 / 193

Table 1.4-1
Determining the technical condition of engine by discerning principal noises and knocks
Zone where
knocking is
audible
Nature of knocks Point (joint of
parts) where
knocking is
possible
Thermal
condition of
engine
Engine running
duty
Conclusion about fitness for
further service
Cylinder area Clear sharp metallic clink Piston pin to
connecting rod
small end
Warm Under load with
sudden transfer
to higher speed
Discontinue motorcycle
operation. Should knocks
disappear if the ignition is
retarded, adjust ignition timing.
If this does not help, remove
carbon deposit from combustion
chamber and, if need be, replace
piston pin, selecting one to
match the color marking of
connecting rod small end.
Ditto Knocking is less clear and
becomes louder once
engine heats up
Piston pin to
piston boss
Ditto Ditto Ditto
Brittle metallic clink
which increases with speed
variation and becomes less
audible when engine is
warmed up.
Piston to
cylinder
Cold Idle speed Continue operation, if clink
disappears after warming-up of
engine. When repairing, replace
piston.
Similar knocks are audible
when piston pin gets
seized in connecting rod
small end.
Discontinue operation. Replace
piston and piston pin.
Central portion of
engine crankcase
Dull knocks of medium
volume
Connecting rod
big end to
crankpin
Random At idle speed
and especially
when
motorcycle
“drags” in travel
with throttle
valve lowered
only partially
Discontinue operation. Repair
the engine.
Engine crankcase
at points of
bearing location
Dull low-tone knocks Main bearings to
crankshaft
Warm Under load and
once throttle
valves are
suddenly open
Discontinue operation. Repair
the engine.
In the area of
gears location
Frequent (clattering)
metallic rolling rattling
(inconstant as to its tone)
Timing gear Ditto Idle running Operation is possible. When
repairing engine, replace faulty
gears.
Cylinder heads Frequent ringing knocks
which increase with
speeding up irrespective of
engine load
Valves to valve
seats
Warmed Idle running and
free wheeling
Motorcycle operation is
possible. Readjust clearance.
Grind-in valves, when repairing.
Clutch cavity Clear metallic clink Clutch discs Random Clutch engaged Operation can be continued.
Inspect clutch when repairing
engine/
Zone where
knocking is
audible
Nature of knocks Point (joint of
parts) where
knocking is
possible
Thermal
condition of
engine
Engine running
duty
Conclusion about fitness for
further service
Rear end of
engine
Dull loud knocking which
disappears once clutch is
fully engaged
Flywheel to
crankshaft
Idle running,
clutch released
Discontinue motorcycle operation.
Remove clutch, flywheel, check key
joint, remount flywheel and fasten
reliably
Zone where
knocking is
audible
Nature of knocks Point (joint of
parts) where
knocking is
possible
Thermal
condition of
engine
Engine
running duty
Conclusion about fitness for further
service