Proper engine speed control is not just a whim of the owner, but a necessity for the preservation of the power plant life. Tohatsu The 9.8 hp series has proven to be reliable two-stroke units, but the standard equipment often does not include the dashboard. The installation of the tachometer allows the driver to accurately put the engine on operating mode, avoid overloads and save fuel, which is critical for long crossings or fishing.
In the process of upgrading the dashboard, the key is to connect the reader correctly. Errors at this stage can lead to incorrect readings or even damage the electronics of the boat. In this article, we will discuss all the technical nuances that will help you to equip your own boat. outboard accurate measuring device, observing all safety and tightness standards of connections.
Before you start installation, you need to make sure that the chosen device is compatible with the ignition system of your engine. Modern digital tachometers are universal, but require the correct adjustment of the number of cylinders and type of magneto. Tohatsu 9.8 CDI system is characteristic, and it is on work with it that we will focus when laying wiring and choosing the signal pickup point.
Choosing the right tachometer for Tohatsu 9.8
The marine equipment market offers a wide range of appliances, but not all of them work equally well with Japanese two-strokes. The focus should be on the range of speeds measured and the way they connect. For a 9.8 hp engine, the device with an upper limit of the scale of 10,000-12,000 rpm is considered optimal, which allows you to see the full picture of the operation. crankshaft without going beyond the dimensions.
Analog and digital devices are important. Analog models are easier to perceive on a glance, but digital models provide high accuracy of reading pulses. When choosing, make sure that the device supports the operation of a generator coil (magneto), as connecting to high-voltage wire on these motors can be unsafe and difficult to implement. It is critical to choose a tachometer with IP67 protection or higher, as salt water spray quickly disables unprotected electronics.
Also worth noting is the built-in motorcycle watch counter, which is extremely useful for maintenance planning, candle replacement and condition checks. transmission oilMany owners. Tohatsu They prefer models with lighting, which makes it easier to read readings at dusk or in poor visibility.
- 🔍 The measurement range should cover the maximum engine speed with a margin of 20%.
- 💧 The level of moisture protection of the shell must comply with the marine standard not lower than IP67.
- ⚡ The power supply type must be compatible with the 12V or 1-15V onboard network.
- 📏 The dimensions of the device should allow ergonomic placement on the tiller or torpedo.
Required tools and materials
The quality of the installation depends on the preparation of the workplace and the availability of the right tool. Tohatsu 9.8 You'll need a standard auto mechanic kit, supplemented by specialized wiring tools, and you don't have to try to do the knee job, because the vibrations and moisture require perfect tightness.
The main focus is on insulation materials. The usual PVC insulation on the boat will quickly dry out and peel off, so use adhesive-layer shrink tubes and specialized marine spray preservatives. To drill holes in the plastic casings of the engine or the tiller, you will need a sharp first drill or crown of the appropriate diameter to keep the edges of the hole smooth and barbed.
⚠️ Warning: Before starting any work with the electrical part, be sure to remove the cap from the spark plug. This will prevent accidental start of the engine and protect from high voltage electric shock.
The list of equipment required includes not only the tool, but also consumables to create a reliable route for the cable. The cable must be multi-core, with tinted copper, resistant to oxidation. The wire section is usually 0.5-0.75 mm2, which is enough for signal transmission and power.
☑️ Tools for tachometer installation
Determination of the signal point on Tohatsu
The hardest part of the installation is finding the right place to connect the signal wire. Tohatsu The tachometer signal is taken directly from the ignition coil (magneto), which is located under the flywheel, but you don't need to climb under the flywheel for this: manufacturers have provided a special output or the ability to connect through a standard connector.
The 9.8 hp model often uses a single-cylinder system, which makes it easier to search. The signal wire is usually white or white and black in the harness that goes from the stator to the switch. If you connect a universal tachometer with a clasped probe, you can place it on the outer wire of the coil, but on the other hand, you can put it on the outer wire of the coil. Tohatsu Most often, a tie into a low voltage circuit before the coil is required.
To determine the wire accurately, use the electrical circuitry of your motor. If the circuit is lost, you can use the multimeter in AC mode, scrolling the starter and measuring the voltage at the contacts of the connector. On the desired wire, there will be voltage surges synchronous with the scrolling of the engine.
| Color of wire | Function | Voltage (AC) | Note |
|---|---|---|---|
| White/Black | Tachometer signal. | 1-15 V | Main signal wire |
| Red. | Charging/Powering | 12-14 | To power appliances |
| Black. | Massa (Ground) | 0 In | Common minus |
| Blue/Yellow | Stop-motor | Closing | Emergency stop circuit |
What to do if the colors of the wires do not match?
The color markings may vary from year to year for Tohatsu 9.8. If the colors don't match the pattern, make sure to ring the chain with a multimeter from the coil to the connector. The signal wire goes directly from the stator output (usually 1 or 2 contacts) to the CDI unit.
Installation and wiring process
Once the connection points are identified, the physical installation begins, the cable must be laid so that water does not enter the connection points and the wire is protected from rubbing against moving parts or sharp edges of the metal. The cable is stretched along the standard harness, fixed with plastic clamps every 15-20 cm.
When you connect the wires, use the method of twisting and then soldering. The twisted veins must be heated with a soldering iron with a roanifoil so that the solder penetrates deep into the connection, creating a monolithic contact. Once cooled, the soldering site is isolated by thermal shrinkage, which must be heated to the protrusion of the glue from the ends of the tube. leakyness knot.
The attachment of the device itself depends on the type of device. If it is a rumble tachometer, it is attached with clamps to the gas control handle. If the device is remote, a hole will be drilled in the torpedo or engine casing. It is recommended to treat the edges of the hole and cover with silicone before installing the device so that water does not flow into the body.
- 🛡️ Lay the cable in a corrugated tube to protect against mechanical damage.
- 🔌 All connectors are treated with a spray-lubricant for electrical contacts.
- 🚫 Avoid putting the wire next to the high-voltage candle cap to avoid interference.
- 🔩 Use stainless screws to fasten the device body.
⚠️ Warning: Do not run the signal wire parallel to the high-voltage candle wire over a long distance. This can cause tips, and the tachometer will show chaotic speeds.
Adjustment and calibration of readings
After you're physically connected, you need to configure the device to display the data correctly. Most universal tachometers have a switch for the number of cylinders or modes of operation. Tohatsu 9.8The rod, which is a single-cylinder engine, you have to set the appropriate mode. Some models do this by a jumper, others by software through button clamping.
If the tachometer shows understated or overstated values, calibration may be required. Some advanced models allow you to enter a conversion factor. Testing the readings is best done using a laser tachometer aimed at the pulley of the crankshaft (if there is a mark) or comparing it with a reference device on the stand. In the field, you can focus on the characteristic sound of the exit on the stand. gas-fisted, which this model comes about 5000-5500 rpm.
It is important to check the stability of readings in different modes of operation. When idling, the arrow or numbers should not “walk”, the tolerance is about 50-100 revolutions. If the readings are unstable, check the quality of the mass contact and the reliability of the signal wire connection.
For precise calibration, use a multimeter with frequency measurement (Hz). The pulse rate on a single-cylinder motor is equal to the number of revolutions divided by 60. For example, 3000 rpm = 50 Hz.
Typical errors and troubleshooting
Even with a careful installation, there can be problems, and the most common is the lack of readings or the randomness of readings, which is often associated with poor mass contact, the engine and boat must have the perfect electrical connection, and an oxidized ground bolt can cause the entire system to malfunction.
Another common mistake is the wrong choice of tachometer mode: if the device is set to 4 cylinders and the engine is single cylinder, the readings will be 4 times less than real. Carefully study the instructions for the device. Also, problems can arise from the use of poor-quality spark plugs, which give a weak spark, not enough to confidently read the signal.
If the tachometer is going off the scale or high, check if the signal wire is in range of the high-voltage discharge. Shielding the wire or changing its track usually solves the problem. In rare cases, you may need to install an additional capacitor in the signal circuit to smooth the pulses.
⚠️ Warning: If the engine stops starting or is interrupted after the tachometer is installed, immediately turn off the signal wire of the device.
Caring for the device in marine conditions
The marine environment is aggressive not only for metal, but also for electronics. Salt mist penetrates into the smallest cracks and, drying, forms a conductive plaque. To keep the tachometer lasting for a long time, after each foray into salt water, the dashboard and the exit points of the wires should be wiped with a wet cloth and then with dry rags.
Once a season, it is recommended to check the tightening of the screws and the condition of insulation. Tohatsu 9.8 It's high enough, and the attachments may weaken over time, and also inspect the cable entry points in the case, so if the sealant has gone, it needs to be updated by removing the old layer and degreasing the surface.
For the winter period, it is better to remove or safely preserve the tachometer, treating the contacts with spray protection. Keeping a boat under the awning does not guarantee protection against condensation, which can cause corrosion of the internal contacts of the device.
The main secret of the longevity of the tachometer is not so much its initial sealing, but regular maintenance and removal of salt deposits after each trip.
Can I connect a tachometer without soldering using only a twist?
Theoretically, you can, but on a boat it is highly discouraged, the vibration and moisture will quickly oxidize the twist, the contact will disappear, and the reading will become incorrect, and the soldering with thermal shrinkage is the only reliable option for marine engineering.
Why does the tachometer show speed when the engine is turned off?
This can be due to residual charge in the capacitors or tips from other devices. If the readings persist for a long time, check the power circuit: perhaps the tachometer is powered from the circuit, which does not open when the ignition is turned off.
Does the installation of the tachometer affect the Tohatsu engine warranty?
By itself, the installation of additional equipment does not remove the warranty, unless there is an interference with the regular wiring with the violation of the integrity of the insulation of the main harnesses or damage to the engine components.
What is the maximum current a tachometer can consume?
Consumption of modern electronic tachometers is minimal and usually does not exceed 50-100 mA. They do not create a noticeable load on the generator coil of the engine 9.8 hp.