Upgrade of the outboard motor Yamaha 9.9 Often starts with a question of comfort, and one of the most desirable improvements is the introduction of an electric starter system. Owners of these reliable two-stroke units have put up with the need to pull the starter cord for years, especially after long parking or in cold weather. But technological progress is not in place, and today turning manual start into the press of a button is a real and affordable task for any enthusiast.
It is worth noting that the factory equipment of engines Yamaha 9.9 Most often, it does not involve the presence of an electric starter, unlike more powerful models or four-stroke analogues. That is why it is precisely about the competent installation of additional equipment, rather than simply maintaining the regular system. The right approach to the selection of components will save the engine life and ensure stable operation in all conditions.
Before you start buying parts, you need to clearly understand the design of your power unit. Two-stroke engines have their own features of the starter system, which are critically important to consider when planning an upgrade. The key is the compatibility of the flywheel and Bendix gear with a specific Yamaha 9.9 crankcase model, as there are no universal solutions here.
Principle of work and design features
The electric start system on small outboard motors is based on the interaction of the starter-reducer mounted on the cylinder block and a special flywheel with a cogwheel. Unlike in automotive systems, where the starter is constantly engaged with the flywheel, the outboard motors use the Bendix mechanism. It pushes the starter gear forward only when the electric motor is rotating, providing engagement with the flywheel.
To implement this scheme, Yamaha 9.9 You need to replace your regular flywheel with a modified version or a transition hub. The standard Yamaha two-stroke flywheel doesn't have the gear wreath necessary to engage. Trying to set the starter without changing the flywheel will only result in the Bendix gear idling and no engine starting.
It is also important to consider the presence generator-coil Some of the Yamaha 9.9 engines already have Lighting Coils, but they may not be enough to keep the electric starter running without modifications, and most require a separate rectifier or a more efficient coil.
⚠️ Warning: Installing the starter on a flywheel without a cogwreath is strictly prohibited. This will lead to rapid wear of the Bendix gear and possible jamming of the mechanism in the engine body.
Necessary components for modernization
To make the project successful, you'll need to assemble a complete set of equipment. Yamaha 15 or 20 It's not going to be enough, because the seats and the electrical circuitry may be different, and the basis of the system is the electric starter itself, which has to be airtight and vibration-resistant.
Besides the mechanical part, the electrical binding is critical. You will need thick copper wires that can withstand a starting current of up to 100-150 Amps, as well as a reliable relay starter (solenoid).
Below is a table of the main components required for conversion:
| Component | Appointment | Requirements |
|---|---|---|
| Electrical starter | Flywheel rotation | 12B compatible with Yamaha 9.9/15 |
| A flywheel with a crown | Bendix hooking | Cone 1:16 or 1:18 (model) |
| Starter relay | Current switching | Minimum 150A, waterproof |
| Battery | Powering the system | AGM or GEL, from 30 AH |
The launch button should be placed in a convenient position on the bumper or on the remote control panel, and it is recommended to use a button with a return to the original position and protection from accidental pressing, for example, with a lift cap.
Preparation and dismantling
Before installing new equipment, the engine must be thoroughly prepared, the first step is always to disconnect the fuel hose and candle caps, and safety when working with flammable liquids and rotating mechanisms should be a priority.
To access the flywheel, you need to remove the top casing of the engine and the ignition system. Carefully disconnect the wires from the ignition coil and sensors. When removing the flywheel, be sure to use a special remover, since blows with a hammer can damage the crankshaft or the flywheel itself. The shaft carving often has left threads, which should be considered when unscrewing the nut.
After dismantling the regular flywheel, carefully inspect the seat on the crankshaft. The presence of bullies or corrosion is unacceptable. If you plan to install a starter from a more powerful model, you may need to tear down the seat or use transition bushings, but this requires high qualification.
☑️ Preparation for installation
The dismantling process also includes checking the condition of the crankshaft coils, and since the scope of the work involves disassembling the top of the motor, replacing the coils preventively will be a smart solution to avoid water entering the crankcase in the future.
Starter and flywheel installation process
The installation starts with the installation of a new flywheel with a cogwreath. Make sure that the veneer sits tightly in the groove of the shaft, and the flywheel is worn to the end. The flywheel mounting nut must be tightened with the force specified in the service manual for your model. Yamahausing a dynamometer key.
The starter itself is attached to a special bracket that is mounted on the cylinder block instead of the plug or in the intended place. Yamaha 9.9 Additional holes or a transition plate are required to be drilled, and the threaded joints must be treated with a thread fixer and lubricant to prevent corrosion.
The Bendix mechanism must be free to walk in its body. Before final assembly, check the ease of rotation of the gear. If the gear comes out with a jag, the starter may not get engaged with the flywheel, which will lead to a characteristic clanching when you try to launch.
⚠️ Attention: When tightening the starter fasteners, do not make excessive efforts. the aluminum alloy of the motor body is easily damaged, which will lead to leakage or cracks.
Once the mechanical part is installed, assemble the ignition system back. Make sure that the gap between the flywheel magnets and the ignition coil (or CDI sensor) is normal, usually 0.3-0.5 mm. An improper gap can lead to a slight spark or damage to the coil.
Electrical circuit connection scheme
The electrical part requires maximum accuracy. The main circuit runs from the battery plus terminal through the fuse (usually 30-50A) to the starter relay, and then to the starter itself. The sub-wire should be as short as possible and go directly from the battery to the motor body or starter.
The relay is controlled via the start button. A thin wire from the button signals the control contact of the relay. To protect the control circuit, it is also recommended to install a small fuse on 5-10A. All connections should be soldered and thermally shrinked or filled with sealant.
Example of connection sequence:
- 🔋 Battery (+) → Fuse 40A Starter Relay (thick contact).
- ⚡ Starter relay → Electrical starter (thick contact).
- 🔘 Start button → Fuse 10A Starter Relay (thin control contact).
- 🌊 Massa → Battery (-) Motor body/starter.
Should I change the rectifier?
In most cases, the regular Yamaha 9.9 rectifier is not enough to charge the battery when the starter is running. It is recommended to install a separate rectifier-regulator connected to an additional winding or a separate coil to avoid battery discharge during movement.
After you've assembled the entire circuit, check the voltage. The battery terminals must have at least 12.5 volts before starting. When you press the start button, the voltage should not fall below 10 volts. If the drop is greater, there is not enough contact somewhere or the wire cross section.
Setup and first start
The first start of the upgraded engine is a crucial moment. Before you turn the starter, make sure that the gas handle is in the starting position and the kill switch is activated. The gas handle on the tiller should be smoothly turned to the end and slightly returned if the engine is equipped with a mixture enrichment system at start.
Press the start button for 2-3 seconds. If the motor is not catching, do not hold the button for longer than 5 seconds, so as not to overheat the starter and not to discharge the battery. Give the system a minute rest before the next attempt. After successful start-up, check the generator: battery voltage with the engine running should rise to 13.5-14.5 Volts.
During the break-in, periodically check the temperature of the starter body and the reliability of the mounts. Vibrations can weaken the bolts, so after a few hours of work, it is recommended to stretch all connections.
Use a WD-40 spray or similar penetrating lubricant to treat relay contacts and start buttons before installation – this will prevent oxidation in high humidity conditions.
Typical problems and their solution
In the process of operation, there can be situations when the system is not working correctly. The most common problem is the starter clicks, but does not spin. This indicates either a dead battery, or poor contact in the power supply chain, or a malfunction of the relay itself. Check the voltage under load.
If the starter is spinning, but the flywheel is not turning, it means that the Bendix gear slips, it can be caused by wear of the gear, dirt or oil on the flywheel teeth, it requires dismantling and cleaning the mechanism or replacing worn parts.
Another common issue is fast battery discharge, often due to a rectifier malfunction or a leak in the wiring, and check the integrity of the wire insulation, especially in the areas where you pass through metal partitions.
The stable operation of the electric starter on the Yamaha 9.9 depends not so much on the power of the starter itself, but on the quality of the connections and battery capacity. Poor contact eats up to 30% of power.
Regular maintenance of the electrical start-up system will prolong the life of the equipment, once a season it is recommended to remove the protective casings, clean the contacts of oxides and check the tension of the wires. Yamaha 9.9 With the electric starter, it becomes much more comfortable to manage, making every fishing fun.
Can I install an electric starter on a Yamaha 9.9 without replacing the flywheel?
No, you can't. The regular flywheel doesn't have the cogwreath needed to engage the Bendix gears. Attempting to launch without replacing the flywheel will damage the starter.
Which battery is better to choose for a 9.9 hp outboard motor?
The best choice will be AGM or GEL batteries with a capacity of 30 Ah. They are resistant to vibration, do not require maintenance and can work in any position, which is important for a boat.
Do I need to change the wiring when installing an electric starter?
The Yamaha 9.9 standard wiring is not designed for high starter currents, but instead requires a new chain to be laid with thick copper wires (at least 10-16 mm2) directly from the battery to the starter through the relay.
Is the Yamaha 15 compatible with the 9.9?
Often, the starters from the Yamaha 15 and 20 two-stroke engines are compatible on the seats, but you need to check the length of the Bendix shaft and the height of the installation, as the cylinder blocks can have design differences.