The correct operation of the throttle control system is the foundation for safe and comfortable operation of water transport. gas-tuning Often causes unstable idling speeds, speed dialing jerks, or, more dangerously, the inability to lose traction in an emergency situation. Owners face problems with dissynchronizing cable actuators, especially on multi-cylinder units, where mismatching even by millimeters can lead to overheating or detonation.
In this material, we will analyze in detail the process of adjusting the mechanical part of the drive and the fineness of tuning the fuel mixture in the carburetor. It's important to understandthat on two-stroke and four-stroke engines the principles of operation are similar, but the nuances of adjustment may differ depending on the manufacturer, whether it is a manufacturer or not. Yamaha, Mercury or TohatsuWe're going to go from the initial diagnosis to the final break-in, eliminating common errors.
Diagnostics of the mechanical part of the drive
Before you can get a screwdriver and adjust the screws of the quality of the mixture, you need to make sure that the mechanics are working, and often the problem lies not in the fuel system, but in the banal wear or improper cable laying. Throttle CableIf the cable has inflections, crinkles, or is too tight inside the shirt, the carburetor or throttle of the injector will not open smoothly. Visually inspect the entire path of the cable from the hummel or control box to the motor itself.
Pay special attention to the entry and exit of the cable from the protective casings. There is most often moisture and salt accumulating, causing corrosion and jamming. For two-stroke motors, the backlash is critical at the connection of the cable with the throttle lever. If you see the free passage of the gas handle when the valve has not yet begun to open, then you need to adjust the tensioner. Tie-tieing shall be such that the backlash is excluded, but there remains a microscopic free-range reserve so that the flap can be completely closed by the action of the return spring.
⚠️ Attention: Never leave the gas cable in a position where the throttle is ajared at idling, which will lead to higher than normal speeds, which is dangerous when maneuvering in port and can cause the engine to overheat at low speeds.
Check the condition of the return springs on the carburetor or throttle assembly, and their task is to immediately close the valve when the handle is released. If the spring is stretched or broken, the motor will continue to pull even after the gas is discharged. Suzuki and Yamaha double springs are installed for reliability; replacing one of them is unacceptable, you need to change the set.
Lubricate the cables with Cable Lubes with long sputter nozzles. The usual Litol-24 lubricant will thicken in the cold, and WD-40 will wash away the residue of the lubricant and dry the insides of the cable.
Adjustment of cables on multi-cylinder engines
The most difficult task in the tuning process is to synchronize the carburetors on engines with two or more cylinders. If one carburetor opens earlier than the other or has a larger flap stroke, the engine starts to work unevenly, triple and lose power. The tuning is done through a system of levers and rods connecting the carburetors with each other. Primary adjustment always begins with the complete closure of all throttles.
Make sure that with the fully released gas, all the flaps fit tightly against the walls of the diffuser. Then, slowly turning the control lever, watch the moment the first flap begins to open. All the flaps must start opening simultaneously. If one opens earlier, you must bend or unbend the connector (link) or adjust the screw tip of the cable. For fine-tuning, use a tachometer connected to the candle tips or service socket.
☑️ Checking the synchronization of carburetors
When adjusting the maximum stroke of the valves (Wide Open Throttle - WOT), remember that the valve should open 100%, but not rest on the body with a force that can deform the mechanism. Mercury and Parsun There are plastic thrust tips that wear out over time, creating a backlash, and replacing these consumables often solves the problem of "floating" turns better than a long fuss with screws.
| Parameter | Normal value. | Sign of malfunction | Elimination method |
|---|---|---|---|
| Idle (Idle) | 850-950 rpm | The engine is dead or roaring. | Adjustment of the damper screw |
| Synchronicity of opening | simultaneously | Trouble, vibration. | Adjustment of traction between carburetors |
| Full gas (WOT) | 100% move | Not getting max. | Adjustment of the length of the cable |
| The spring's return | Instant. | The damper sticks. | Replacement of spring or axle cleaning |
Basic setting of the carburetor
Once the mechanics are in place, we move on to fine-tuning the fuel supply. In a classic carburetor, three basic elements are responsible for this: the idle mix quality screw, the mix quantity screw (throttle stress) and the jeeps. You should always start with a Low Speed Mixture. On a warm engine, slowly twist the screw until the speed starts to fall, and then twist it back 1.5-2 revolutions (base factory setting).
Then you look for the middle ground. So, as you smoothly twist the quality screw, listen to the engine. In a certain position, the speeds may rise a little bit, which is the most optimal burning moment of the mixture. If you twist the mixture further, the mixture will become poor, and the engine will start to stall. The task is to find the position where the engine is most smooth and stable. Tohatsu and Nissan There is a high sensitivity to this parameter.
⚠️ Attention: The engine operation on too poor mixture (little gasoline, a lot of air) is dangerous overheating of the piston group and burnout of the piston. If after setting the engine squeals at high speeds or candles turn white - immediately enrich the mixture.
The throttle propeller only regulates the minimum speeds when the throttle is closed. Don't try to adjust the idle with this screw alone, ignoring the quality of the mixture. The right setup is when you put the speeds to the right level with the quality screw, and the number screw only slightly adjusted the position of the valve so that it is not clamped.
What are transitional regimes?
Transition modes are the moment when the throttle opens from idle to medium revs. At this point, the accelerator pump system (if any) or the carburetor transition holes come into operation, and if in this mode the engine "fails" and dies when abrupt gas is added, then the mixture is poor in transition modes or the accelerator pump is faulty.
Setting up the needle and jelly (medium and high loads)
If the motor is idling perfectly, but it twitches when the gas is opened sharply or it does not develop full power, the problem lies in the adjustment of the throttle needle or main giclera. The needle attached to the throttle covers the hole in the sprayer. When we raise or lower the locking ring on the needle, we change the composition of the mixture in the range of 1/4 - 3/4 opening of the throttle.
Raising the locking ring (the needle rises above) enriches the mixture, lowering it makes it poorer. If the engine choked and smoked when the gas was opened sharply, the mixture was too rich, the needle should be lowered (or rearranged lower). If the engine sluggishly gains momentum and shoots at the muffler, the mixture is poor, we raise the needle. Honda and Yamaha needles have a complex profiled shape, and replacing the standard needle with a tuning one can give a noticeable increase in elasticity.
The High Speed Jet is responsible for full speed, and it's done experimentally, often by the opposite method. If the engine is not running at full speed, the candle is black and smoked, the jikler is too big, you need a smaller number. If the candle is white, the engine is warming and not spinning, the jikler is small, you need a bigger number. Critical: When replacing chicklers, use only original calibrations or proven analogues, since the diameter of the hole affects fuel consumption and engine life.
A properly selected throttle needle eliminates dips during acceleration and makes the engine work elastic throughout the rev range, except for idling and full power.
Features of Injection Systems (EFI)
Modern four-stroke engines and powerful two-strokes are increasingly equipped with electronic fuel injection (EFI), where mechanical tuning of cables remains relevant, but the adjustment of the mixture is done programmatically through the ECU. throttle position sensor (TPS).
If the TPS is set up incorrectly, the computer receives false information about the position of the gas pedal. This can cause the engine to stall when the gas is discharged or, conversely, do not reset. Calibration TPS often requires the connection of a diagnostic scanner or perform a certain sequence of actions (pressing buttons, turning the key) described in the service manual of a particular model. Mercury SmartCraft or Yamaha Command Link.
In injection systems, control of the fuel ramp pressure and the condition of the injectors is also important. If the nozzle is clogged or poured, no electronic adjustment will help. Cleaning the nozzles in an ultrasonic bath is a standard maintenance procedure for engines older than 3-5 years, especially if gasoline with an octane number below the recommended.
Final check and break-in
After all the adjustments, you need to run a test run. The engine must start confidently, keep idle at a stable rate without any extraneous vibrations. There should be no dips when the gas is opened sharply, and when the gas is dropped, there should be an instant return to idle. Be sure to check the engine under load (on water), as in the air the engine behavior can differ due to the lack of water resistance and the difference in cooling.
If you have been replacing jelly or a serious bulkhead carburetor, it is recommended to conduct a short run in gentle mode. Let the engine work 10-15 minutes at medium speeds, so that the temperature stabilizes and burn out possible residues of lubricant or cleaner carburetor. After cooling the engine, it is useful to check again the tightening of the carburetor screws, as from vibration and temperature expansions they could weaken.
⚠️ Attention: After setting up, always check for no fuel leaks at the carburetor-intake manifold and fuel hoses. Gasoline vapor in the boat hold is a direct threat of explosion. Use soap solution to look for micro-cracks in the hoses.
Properly adjusting the gas extends the life of the engine for years. Regularly check the condition of the cables and the quality of the mixture, especially at the beginning of the season, and your outboard motor will delight with stable traction and economical fuel consumption. Remember that each engine is different, and sometimes iterations of adjustments are required to achieve the perfect result.
Why are the settings getting lost?
The carburetor settings can be affected by vibration (screws twist), changes in atmospheric pressure (when traveling in the mountains), or fuel quality, and by the wear and tear of the needle and saddle, which requires more frequent adjustment on older engines.
Frequently Asked Questions (FAQ)
How often should you adjust the carburetor on the outboard motor?
Preventive adjustment checks are recommended at the beginning of each season, and if the engine is new, the first setup is required after running (the first 10 hours), as the parts are rubbed and the gaps change.
Why does the engine stop when you add gas?
It's a classic sign of failure, and it's a poor mix in transition modes (you need to lift the throttle needle), a clogged accelerator pump (carburetors with it), or too low idling speed, and it's also worth checking the air filter -- if it's clogged, the mixture will be overenriched, but the dynamics will disappear.
Can the carburetor be adjusted to hearing without a tachometer?
Experienced motorists can idle by ear to determine the level of operation. However, to fine-tune maximum speed and synchronize multi-cylinder engines, a tachometer is mandatory. Eye-to-eye setting can lead to maximum speed, which will reduce the engine life.
Does the octane number of gasoline affect the gas setting?
Yes, it does. Going from 92 to 95 (or vice versa) may require adjustment of the ignition advance angle (if there is adjustment) and easy adjustment of the mix, and using gasoline with an octane number below the manufacturer's recommended result in detonation that cannot be eliminated by adjusting the carburetor.