Check spark plugs

On appearance of the spark plugs can diagnose the condition of the engine. Clean, white plaque without insulator spark plug shows too lean fuel mixture. This also indicates that the spark is too hot (heating from the central electrode away slowly). It is necessary to adjust the air-fuel ratio, or replace the spark plug.

Dry deposition of soot indicates too rich mixture. If the insulator is covered by light brown touch the mix structure is optimum also the engine is in good condition.

Too large and too small electrode gap, in which the size varies spark reduces the efficiency of the engine. The gap must always conform to the specifications.

The gap is checked by a wire template or probe. Adjust the gap podgibaniem side electrode can be a special tool. The central electrode in no case can not be bent, as this may cause damage to the insulator and a candle exit out of operation.

Before installing a spark plug in the engine, check that the thread is clean and undamaged.

There are two types of seals installed in the cylinder head with a flat seat and elastic (steel or copper-asbestos) seal or conical seat without gasket. When installing a new spark is first necessary to verify a seal is provided in the cylinder head, the diameter and length of the threaded portion. If you set a candle with a long threaded portion in the head with a short thread, the protruding portion candles covered with soot and tar deposits lead. The candle will overheat, possibly melting thread.

When releasing a spark can damage the threads in the cylinder head. If the short threaded part of the spark in the cylinder head is formed soot and various deposits clog the thread, there is its fusion. After a long work has to go tap the threaded part of the cylinder head, but so that no dirt enters the cylinder.

The most important parameter characterizing a candle, a temperature mode of its elements, and above all the central electrode and the surface of the insulator. The main problem in the manufacture of candles for the high-speed engine is the implementation of conflicting demands. On the one hand, one must ensure a sufficiently high temperature of the insulator that during prolonged operation at low load and idling to prevent the formation of soot on it, which leads to bypass, especially at low temperatures. In the transition to heavy loads at high temperature the self-cleaning insulator of a candle burning out due to its adjournment. On the other hand, under high load the temperature of the central electrode and the lower part of the insulator should not exceed the upper limit at which there is surface ignition (ignition of the mixture before the spark ignition system). From cycle to cycle ignition occurs earlier and earlier, the temperature rises to the details as long as that is not burned at best case the candle, in the worst - the piston. So because of the small candles can be in big trouble.

How to prevent the possibility of pre-ignition? First of all, you need to follow the right (under the instruction) by setting the ignition timing angles, avoiding too early ignition.