3 - MAINTENANCE
79
MEASURING THE COMPRESSION PRESSURE
AN INSUFFICIENT COMPRES-
SION PRESSURE WILL LEAD TO
A LOSS OF POWER.
BEFORE MEASURING THE
COMPRESSION, IT IS IMPOR-
TANT TO ENSURE THAT THE
VALVE CLEARANCES ARE CO-
RRECT.
1. Check:
- Valve settings.
Outside that specified => Adjust
See the “ADJUSTING VALVE SETTINGS” section
2. Start up:
- The engine and leave to warm up for a few minutes.
3. Stop:
- The engine.
4. Remove:
- Spark plug.
BEFORE REMOVING THE SPARK PLUG BLOW AROUND IT WITH COMPRES-
SED AIR TO REMOVE ANY DIRT, THEREBY PREVENTING THIS FROM FALLING
INTO THE ENGINE.
5. Fit:
- Compression meter (1).
6. Measure:
- Compression pressure.
Standard value: above 15Kg/cm
2
Service limit: 13Kg/cm
2
Steps for measuring:
- Start the engine with the throttle fully open, until the compression reading stabilises.
If the maximum permitted pressure is exceeded => Inspect the head, valve surfaces and piston head for
carbonising.
If it is below the minimum pressure=> Inject a few drops of oil into the cylinder and measure again.
Follow the instructions in the table:
COMPRESSION PRESSURE (WITH OIL INJECTED INTO THE CYLINDER)
READING
DIAGNOSIS
More than without oil
The same as without oil
Worn or damaged pistons or piston rings.
Possibility of a defect in the seats, valves, head gas-
kets or piston => Repair.
WARNING
N.B.
Содержание GPR 125 Racing
Страница 1: ...WORKSHOP MANUAL GPR 125 4 stroke ...
Страница 30: ...2 PDI Pre delivery inspection 30 2 PDI Pre delivery inspection PDI Pre delivery inspection 31 2 1 ...
Страница 169: ...6 COOLING SYSTEM 169 6 1 DIAGRAM OF THE SYSTEM ...
Страница 170: ...6 COOLING SYSTEM 170 ...
Страница 179: ...7 LUBRICATION SYSTEM 179 7 1 DIAGRAM OF THE SYSTEM ...
Страница 180: ...7 LUBRICATION SYSTEM 180 ...
Страница 192: ...8 CHASSIS 192 FITTING FRONT SUSPENSION ...
Страница 202: ...9 BRAKING SYSTEM 202 9 BRAKING SYSTEM FRONT BRAKE REAR BRAKE 203 211 9 1 9 2 ...
Страница 247: ...Rev 0 2009 ...