1. The spark plug serves to produce a spark that ignites the fuel in the cylinder. No spark, no combustion, and that is the fault ...
2. Contrary to the general idea, a spark plug is not clear (short-circuiting).
3. Need to change all its spark plugs (same degree tear), theoretically the 100 hours of browsing or most of every start of the season. In practice, this depends on the regulation and operation of your engine.
4. If all the plugs are similar in appearance, have the same rates terms and also the same characteristics (length and diameter of the seat). Is important to use spark plugs recommended by the engine manufacturer and references are printed on the plug and the manual for your motor.
5. When removing spark plugs, no burning need to monitor, ceramics can reach 180 degrees in temperature. To avoid mistakes in the connections of the pipes, change the spark plugs one by one. Gently remove the pipe, unscrew the plug with a wrench 16 or 21, and especially do not force the ceramic (risk of breakage). To tighten the new plug to start manually until your seat is in contact with the butt. Finish tightening regardless of engine temperature, follow the instructions in the table, then:
Torque wrench
Spark plug with taper seat (not together) 2 m / kg
Spark plug with flat seat (with seals) 4 m / kg
No torque wrench
Tighten 1 / 8 back
Tighten 1 / 8 back to muss the board, loosen and retighten 1 / 4 back
Attention: Do not overtighten or damage to the seat of the stock.
6. A spark plug is considered normal, after using the electrode is a light brown color (white on a new plug) and the electrodes are not burned.
Source: Plastimo
Watch NGK-Champion spark plug conversion table on PDF 
