Like this Manual?SAFETY FIRST: Protective gloves and eyewear are recommended at this point.
Run the engine to warm it up before conducting a compression test. Make sure your compression gauge is in good working order and does not leak. Also, the battery should be fully charged.
Remove the spark plugs. See the Spark Plugs topic for more information.
Install the compression tester into the sparkplug hole using a compression gauge adapter and tighten it hand tight.
Special Tools-
Compression Gauge: 57001-221
M10x1.0 Adaptor: 57001-1486
Make sure the transmission is in neutral.
Hold the throttle wide open and use the electric starter to turn the engine over. Crank the engine until the needle on your compression gauge stops rising. Compare your reading with specification.
| Cylinder compression usable range | Standard |
| 700 Models Electric Starter @ 280 rpm | 294 – 520 kPa (3.0 ~ 5.3 kgf/cm2, 43 – 75 psi) |
| 650 Models Electric Starter @ 240 rpm | 320 – 560 kPa (3.3 ~ 5.7 kgf/cm2, 47 – 81 psi) |
Low compression is an indication of excessive engine wear, possibly worn rings or poorly sealing valves, or maybe a tight valve with not enough valve clearance.
High compression is possibly an indication of excessive carbon buildup on the piston or performance modifications.