Stable work boat-engine It's a very important ignition system, and it's a fundamental process that triggers the life cycle of a two-stroke or four-stroke internal combustion engine. Ignition candle It is the final element of this circuit, taking on a high voltage and converting it into a powerful electrical spark inside the cylinder.
Many aquatic motorists underestimate the importance of correctly selecting and regularly replacing this small but critical component. kalyph or violation of the gap between the electrodes can lead not only to loss of traction and increased fuel consumption, but also to fatal damage to the piston group. The use of a candle with an inappropriate thermal regime is one of the main reasons for the detonation of pistons on two-stroke engines.
In this article, we will discuss in detail how to read the label, what is the difference between products of different brands and how to diagnose the condition of the engine by the appearance of the stainless oil. Understanding these nuances will help you avoid expensive repairs and always be confident in the reliability of your car. outboard motor during the watering.
The principle of operation and the role of the thermal regime
The main function of a candle is not just to give a spark, but to do it at a specific point in time, ensuring that the mixture is completely burned. But equally important is the removal of heat from the central electrode and insulator to the cylinder head. heat-regulationIf a candle removes too much heat, it is considered "cold" if too little is "hot."
Choosing the right thermal mode is critical for the longevity engine. The "cold" candle is necessary for high-powered engines operating at high revs, as it prevents from running. ignition At the same time, the installation of a "cold" candle on a slow-moving engine will lead to the formation of a scorch and the skipping of a spark, since the candle will not have time to warm up to a self-cleaning temperature (about 400-500 ° C).
What is a kalili ignition?
Kalilla ignition is the process of ignition of the fuel-air mixture not from an electric spark, but from the hot elements of the candle (central electrode or insulator), which is extremely dangerous for the engine, as it leads to a sharp increase in pressure and temperature in the cylinder, which can cause the piston to burn or break the partitions.
Modern two-stroke outboard motors, such as Yamaha, Tohatsu or SuzukiThey often have strict thermal requirements because of the high degree of forcing. Honda BF or Mercury FourStrokeThey're also sensitive to this parameter, although their temperature is usually more stable, and the wrong choice will lead to either coking or overheating.
The heat number of the candle must strictly comply with the recommendations of the engine manufacturer; experiments with "hotter" or "colder" candles are permissible only when changing the operating mode (for example, prolonged operation on full gas).
Decoding of markings: NGK, Champion and Denso
The market for water-motor equipment is dominated by several major manufacturers whose products are installed in the manufacturer. NGK, Champion and DensoEvery company uses its own coding system, which often causes confusion among owners trying to find a counterpart. Understanding the logic of labeling makes it easy to navigate catalogs.
Company. NGKThe marking is constructed as follows: the first letter indicates the diameter of the thread (B - 14 mm, D - 12 mm), the number after it indicates the kalyl number. Important nuance: NGK has a higher number, the colder the candle. B8HS The number 8 indicates a rather cold candle suitable for forced engines.
American brand Champion They use reverse logic in some series, but most often their markings also contain information about size and thermal conditions. RCJ (Carving 14 mm, turnkey size 16 mm) and RN2C. Denso It uses a system similar to NGK, where the digit also represents the kalyl number, but the scale step may differ. Always check the interchangeability table.
- 🔍 NGK BPR6ESB is a 14 mm thread, P is a protruding insulator, R is a resistor, 6 is a kalyl number, E is a 19 mm thread, S is a standard electrode.
- 🔍 Champion RN2YCR is a resistor, N is a 14 mm thread, 2 is a thermal range, Y is a V-cut on the electrode, C is a thread length of 19 mm.
- 🔍 Denso W20EP-UW is a 14 mm thread, 20 is a potassium number, E is a 19 mm thread, P is a protruding insulator, U is a large gap.
Key parameters: Carving, gap and Kalil number
When you select an analog, you have to take into account three geometric and physical parameters. thread-pointThe standard for high-powered engines is 14 mm, for low-power sailboats (2-6 hp) is often 10 mm or 12 mm. The length of the threaded part also varies: 12.7 mm (1/2 in) or 19 mm (3/4 in) Installing a short candle in a long socket will lead to the accumulation of soak and compression fall, and a long one in the short will lead to the impact of the piston.
The second critical parameter is spark-gapThis is the distance between the center and the side electrode through which the spark passes. For most two-stroke outboard motors, the optimal clearance is in the range of 0.7-0.8 mm. Too small a gap will give a weak spark, prone to blowing out at high speeds, and too large will create excessive resistance for the ignition coil, which can lead to its failure.
⚠️ Attention: Never adjust the gap by acting on the central electrode or insulator - this is guaranteed to crack the ceramics. You can only bend the side electrode using a special probe or candle tool.
The third parameter is availability resistor (interference): In the marking it is usually indicated by the letter "R" (e.g. B)ROutboard Motors create powerful electromagnetic fields that can jam the signals of sonars, GPS-navigators and radio stations. The use of non-resistive candles on a modern boat with electronics is unacceptable, since interference can completely disable sensitive navigation equipment.
To fine-tune the gap, use a round probe. Flat probes can give an error due to the shape of the electrodes. Adjustment should be done carefully, checking the result after each micro-motion.
Recommended clearance for most two-stroke engines: 0.7 - 0.8 mm
Recommended clearance for four-stroke motors (EFI): 0.9 - 1.1 mm
Diagnostics of the engine by color of the sodium
The spark plug is a window into your engine's combustion chamber, and by twisting it out after the engine is running, you can get valuable information about the state of the fuel system and the piston group, and the color and structure of the deposits on the insulator and electrodes will tell you more about the composition of the mixture and the temperature in the cylinder than any compression measurements.
The ideal condition is characterized by the color of the insulator from light brown to gray brown (“coffee with milk”), which indicates the correct ratio of gasoline to oil, a serviceable ignition system and the appropriate thermal regime, while the electrodes are smooth in color without signs of erosion or melting.
| Color/State | Diagnosis. | Action |
|---|---|---|
| white or light gray | Overheating, poor mix, early ignition | Check the angle of advance, carburetor, replace with "hot" |
| Black velvety nagar (dry) | Rich mix, overabundance of butter | Set up a carburetor, check the proportion of the mixture of oil and gasoline |
| Oily black coating (brilliant) | The ingestion of oil from the crankcase, wear of rings | Check the compression, condition of the osteoils and piston rings |
| Melted electrode/insulator | Critical overheating, potassium ignition | Urgently replace the candle with a colder one, check the cooling system |
If you find out squirtThis often indicates that the engine is running on a mixture with excess oil (relevant to two-strokes) or there is an incomplete combustion due to a dirty air filter. carburetor You should check the float chamber level. oily And it leaves marks on the finger, and it's a mechanical problem, because the oil gets into the combustion chamber through worn rings or glands.
Before you twist a candle for inspection, blow the place around it with compressed air or thoroughly wipe it with a brush. Getting even a small grain of dirt or abrasive into the cylinder when screwed in can cause bullies on the cylinder mirror.
Instructions for replacement and maintenance
Replacing spark plugs is one of the simplest but most important procedures maintenance The regularity of replacement depends on the type of motor and operating conditions. For two-stroke engines that are mixed with oil, the life of the candle is lower due to the formation of conductive soak, it is recommended to change them every 50-100 motor hours or once in the active season.
The replacement process requires a minimum set of tools: a candle wrench (usually 16 mm or 21 mm), a gap probe and, preferably, compressed air. It is important to observe the moment of tightening. Insufficient puffing will lead to overheating of the candle (the heat sink will be broken through the thread) and possible loss of compression. Excessive puffing risks damaging the thread in the cylinder head, the repair of which is difficult and expensive.
☑️ Checklist for candle replacement
When installing a new candle, note the presence of a sealing washer. Many outboard motor candles (especially those with 14 mm thread) use disposable washers. Reusing the old washer It's not acceptable, because it's already deformed, and it won't provide the right leakage and heat sink. If there's no washer, just control the tightening force.
⚠️ Attention: Don't use solidol, litol or copper lubricant to carve a candle! At high temperatures, these lubricants can cork, and the next replacement will be impossible to twist the candle without damaging the head of the block.
Launch problems and methods of solving them
The absence of a spark or a weak start of the engine is often associated with candles, but not always the reason lies in the candles themselves. If the engine does not start, the first thing to do is to twist the candle and check for the spark, threading it to the "mass" of the engine (metal part of the block) and yanking the starter. The spark should be bright blue and punch the gap with a characteristic crack. A red or yellow spark indicates a weak coil or a discharged battery.
A common problem is filling the candle, which happens when too much fuel is pumped into the cylinder and the electrodes are covered with a film of gasoline, closing the spark, in which case the candle needs to be twisted out, dried (you can warm it up with a lighter or a hairdryer), blown through the cylinder with an open throttle starter and screwed back in. If the situation repeats, look for the reason in the carburetor or engine control system.
Also, remember to "shelf life" candles, even if they were not in the engine. O-rings and gaskets can dry up with long-term storage. When buying candles "before stock" for the future, make sure that they are stored in a dry place, and their packaging is not broken.
If a new candle quickly fails or becomes covered with soot, do not rush to change the brand - the problem almost certainly lies in the engine settings (mixture, ignition) or mechanical wear of the CPG.
How often should I change the candles on the outboard motor?
For two-stroke engines running on a benzo-oil mixture, the recommended replacement interval is 50-100 moto hours or once at the end of navigation before conservation. Four-stroke motors can take up to 200-300 moto hours, but visual monitoring is mandatory annually.
Can I use car candles in a outboard motor?
Automotive candles often lack sufficient spark clearance, other thermal conditions and, critically, may not have the noise suppression (resistor) required for the onboard electronics of the boat.
Which is better: one expensive iridium candle or a regular one?
Iridium and platinum candles (such as the NGK Iridium) have increased life and a more stable spark, which improves the ignition of depleted mixtures. For older carburetor engines, the difference may not be noticeable, but for modern four-stroke EFI engines, installing the manufacturer's recommended iridium candles will prolong the life of the ignition coil and improve environmental friendliness.
Why does the candle break through the insulator?
The appearance of black stripes on the ceramic insulator (called "tracking") indicates that the spark does not slip between the electrodes, but along the surface of the ceramic onto the body, this is due to damage to the glaze of the insulator, the use of a poor-quality BB wire cap or excess voltage in the ignition system.