Decoding of the two-stroke engine: restoration of the power of the outboard motor

A drop in thrust, difficult start and black exhaust are the first signs that your car is not a good driver. two-stroke Unlike the four-stroke counterparts, two-strokes work on a mixture of oil and gasoline, which inevitably leads to the formation of soot on the piston rings, cylinder walls and exhaust system. Decoxing It is the only way to return the engine to factory specifications without expensive overhaul.

Timely maintenance avoids critical wear on the parts of the cylinder-piston group. If you ignore the coking rings, they lose mobility, they stop snugly fitting to the walls of the cylinder, which leads to loss of compression and power loss. In advanced cases, the coar can cause detonation, which can destroy the piston in a matter of minutes under load.

In this article, we will discuss effective cleaning methods, debunk popular myths about fuel additives and provide a step-by-step algorithm of actions. Tohatsu, Yamaha or Mercury The key is to understand the chemical processes that take place inside the combustion chamber.

Causes and symptoms of engine coking

The main cause of solid deposits is poor-quality combustion of the fuel-oil mixture. When you use cheap mineral oil or break the mixing ratio, the combustion products settle on hot surfaces. Over time, soft soda turns into a hard crust that is difficult to remove mechanically without disassembling the engine.

Another factor is the incorrect running or, conversely, long-term work at idle speeds. At low loads, the temperature in the cylinder is not enough to completely burn out the oil, which accelerates the pollution process, and it is worth noting the effect of bad gasoline with a high content of impurities, which leaves behind resinous fractions.

⚠️ Note: If you notice that the engine began to stall when the throttle was opened abruptly or the work on singles became unstable, this is a sure sign that piston-ring They're lying around and need to be cleaned.

There are a number of indirect ways to determine whether the procedure is necessary: the boat owner may notice an increase in fuel consumption while maintaining the same speed specifications, the smoke from the exhaust pipe becomes thicker and becomes bluish, indicating that oil is burning in large volumes.

• 📉 Significant reduction in the maximum speed of the boat on the water.
• 🔥 Overheating of the engine even at normal temperature of the off-board water.
• 🔊 The appearance of a ringing metal knock (detonation) under load.
• 💨 Black or grey smoke from the exhaust hole.

Choosing a tool for decoking: chemistry vs. mechanics

The autochemistry market offers many drugs for removing sodium, but not all of them are suitable for two-strokeAggressive solvents for four-strokes can damage carburetor rubber seals or ossicles if the concentration is too high. It is important to choose specialized products that are safe for engine materials.

The most popular method is to use liquids poured directly into cylinders through candle holes. LAVR, GZox or ShummaIt softens the soak so you can remove it when you run the engine, and it takes time to react, so it's important to follow the soaking instructions.

There is also a “old-fashioned” method using a 1:1 mixture of acetone and kerosene, which dissolves oily deposits perfectly, but requires extreme caution when used. Kerosene has lubricating properties, which reduces the risk of bullies when first started after treatment, as opposed to pure acetone.

The dangers of popular methods

The use of pure alkali or acids to wash the engine is strictly prohibited, and these substances will instantly destroy aluminum alloys and lead to corrosion of the internal cavities, after which the engine can only be thrown away.

Mechanical cleaning is used in extreme cases when the chemistry is not working, and it involves removing the cylinder head and manually removing the scoop, which is effective but requires high skill, because there is a high risk of damaging the cylinder mirror or leaving the abrasive particles inside.

Type of instrument	Efficiency	Security	Difficulty of application
Specialized chemistry	High.	High.	Low.
A mixture of kerosene and acetone	Medium	Medium	Medium
Mechanical cleaning	Maximum	Low (risk of damage)	High.
Fuel supplements	Low (prevention)	High.	Minimum

Preparation of the engine for the cleaning procedure

Safe conditions must be ensured before any work begins. Decoxing This involves the use of flammable liquids and the engine operating in an enclosed space (if warming up), make sure that the boat is securely attached to the trailer or is on shore, and exhaust gases do not enter the cabin or living space.

The first step is always to warm up the engine to operating temperature, so that the metal of the cylinders expands, and the heated charcoal becomes more susceptible to chemical damage, and it takes 5-10 minutes of operation at medium speeds, after which the engine needs to be turned off.

After heating up, the engine should cool down a little, but stay warm. The optimum temperature is about 50-60 degrees Celsius. If you put cold chemistry in a hot engine, it will instantly evaporate before it can act. If the engine is cold, the reaction will be sluggish.

It is important to turn off the ignition system so that when you scroll the starter or pull the cord spark does not jump. Otherwise, the vapors of the solvent can ignite, which will lead to cotton and ejection of the contents of the cylinder. It is also recommended to remove the air filter to have access to the carburetor if you plan to clean through the intake.

Technology of decoking through candle holes

This is the most common and effective method to clean the combustion chamber and piston-ringAfter the candles are twisted, you need to place the pistons in the middle position, and this is done by rotating the flywheel so that the rings are located approximately in the middle of the cylinder's working area.

Each cylinder is filled with a syringe or oil, and the volume is usually 30-50 ml per cylinder, but the exact dosage is indicated on the bottle of the manufacturer of the chemical, the liquid should cover the piston and the bottom of the cylinder walls.

⚠️ Warning: Do not rotate the crankshaft after the pour of the remedy, unless the instruction requires otherwise. The movement of the piston can squeeze the aggressive liquid into the crankcase, where it mixes with the oil and loses its properties.

After pouring, the candle can be screwed back in (without delaying) or simply closed with the rags so that the vapors do not evaporate. Exposure time varies from 30 minutes to several hours. Some masters leave the composition overnight for deep cleaning, but this requires the use of less aggressive means.

After a while, you need to remove the remaining liquid from the cylinders, to do this, you actively scrolle the engine with a starter several times (first twisting the candles and closing the holes with a cloth) to squeeze the liquefied soda out, only after that you can screw the candles in and start the engine.

Cleaning through fuel system and exhaust

An alternative method involves adding a cleaning compound directly to the gas tank or feeding it through a carburetor, which is less effective against heavy swelling, but is great for prevention and cleaning. vent-window And a silencer that's hard to get by other means.

When fed through the carburetor, the engine runs on a mixture of air and cleaning agent, solvent vapors enter the cylinder where the chemical reaction occurs, and it is important to maintain high revs so that the exhaust temperature is sufficient to burn the coar in the muffler.

• 🛢️ Pour the mixture into the tank in the proportion specified by the additive manufacturer.
• 🏎️ Operate the boat in full load mode for at least 30 minutes.
• 💨 Control the color of the exhaust (it will change).
• 🔄 After the tank is developed, you need to replace the fuel filter.

Remember, this is a cleaning agent that goes through the entire fuel system, and if there's rust or dirt in the tank, they can be pulled up from the bottom and hammered into the carburetor's jelly, so before the procedure, it's recommended to drain the old gasoline and flush the tank.

Completion of procedure and first launch

The most critical moment is the first start after decoking. The cylinders may have residues of aggressive liquid, so the launch must take place in a well-ventilated place, and be prepared for the exhaust pipe to fall thick white or blue smoke, which burns the tan and chemical residue.

The engine may not work smoothly for the first few minutes, let it warm up at idle speeds, then gradually increase the speed. It is critically important not to give full load in the first 10-15 minutes.so that the remnants of the coarse have time to burn out and exit without causing detonation.

After the procedure, be sure to replace the oil in the gearbox (if it gets there) and check the state of the spark plugs. The ignition plugs should disappear, the electrodes will become light. If the candles are black and wet, the procedure may have to be repeated or checked.

⚠️ Warning: If the compression is completely gone after decogging, it may mean that the soak that served as a seal in the cracks has washed out, which requires a cylinder defect and possibly a piston group replacement.

To consolidate the result, it is recommended to add a high-quality synthetic oil for two-stroke engines with detergent additives to the next tank, which will help maintain the purity of the engine and prevent the rapid formation of new coal.

Prevention and care of the two-stroke motor

To avoid having to resort to radical measures, it is important to follow a culture of exploitation: use only the quality gasoline and oils recommended by the manufacturer. Cheap mineral oils burn with a lot of residual products, clogging the engine.

Try not to run long idling. Two-stroke engines like loads that are optimal for the combustion of the mixture. Periodically let the engine gass at full throttle to clean the combustion chamber.

Regular maintenance, including compression checks and visual examination of the candle, will help identify problems early on, and if you notice that the candle has become blacker than usual, this is a signal of a rich mixture or oil problems that need to be addressed before the rings start to coking.

Frequently Asked Questions (FAQ)

Can you do the decoking without removing the engine from the boat?

Yes, in most cases, it is possible. If the spark plugs and the exhaust system are not blocked by the boat's design, the procedure can be done on site, but make sure that the exhaust gases are safely diverted to the side, not to the cockpit.

How long should I keep the product in the cylinders?

The manual usually recommends 30 minutes to 1 hour. For severe cases (high mileage engine without maintenance), the time can be extended to 4-6 hours, but no more, to avoid corrosion of the metal by aggressive components.

Will the engine be able to be knocked out?

If the knocking is caused by the detonation of the coal, then cleaning will help. But if the knocking is mechanical (wear of bearings, rod group), then decoking is useless and can even make things worse by washing out the oil residue. It requires a diagnosis of the mechanical part.

Should I change the oil after the oil is removed?

In a two-stroke engine, the oil burns with the fuel, so you don't have to change it in the crankcase (if you're talking about a mixture), just work out the residues of the mixture. If you have a four-stroke suspension or gearbox, and the chemistry gets there, you have to replace it.