Koso EGT-02R EVO User Guide for Mercury 2-Stroke V6 Outboards

Mike Hill
May 7
4 min read

Monitor and tune your Mercury 2-stroke V6 outboard with precision using the Koso EGT-02R EVO. Learn how to operate the dual EGT and RPM gauge for real-time performance insights, data logging, and engine protection.

This guide explains how to operate and fully utilize the Koso EGT-02R EVO digital gauge, focusing on its EGT, RPM, voltage monitoring, recording, playback, and customization features.

Designed for high-performance applications, this system is particularly useful for Mercury 2.0L, 2.4L, and 2.5L V6 outboard engines used in racing, tuning, and diagnostics.

1. Understanding the Display and Basic Navigation

When powered on, the Koso gauge enters the main screen, which continuously displays real-time engine data.

Left Side: Displays EGT Left (port bank), or Max EGT Left when toggled.
Right Side: Displays EGT Right (starboard bank), or system voltage when toggled.
Bottom Center: Displays current engine RPM, sourced either from a signal wire or inductive pickup.

Navigating the Display:

Press the Left button once to switch between live EGT Left and Max EGT Left.
Press the Right button once to switch between live EGT Right and voltage display.
Hold the Left button for 3 seconds while viewing Max EGT Left to clear that value.
Hold the Right button for 3 seconds on the main screen to toggle temperature units between Celsius and Fahrenheit.

This intuitive layout allows you to monitor your engine’s thermal behavior and electrical system without diving into submenus.

2. Setting Warning Thresholds and Preferences

The gauge allows you to configure alerts for key metrics like EGT and voltage. These warnings are critical for catching lean conditions, detonation, or charging system failures.

Entering Settings Mode:

Hold both buttons for 3 seconds from the main screen to enter the settings menu.

Once inside the settings screen:

Press the Left button to cycle through setting options:
1. EGT L Warning Temperature
2. EGT R Warning Temperature
3. Low Voltage Warning
4. High Voltage Warning
5. Auto Record Delay
6. Backlight Brightness
Press the Right button to adjust the value of the selected setting. The value will blink to indicate it is being edited.

Notes:

EGT warning range: 200–1000°C (or 392–1832°F), adjustable in 1° increments.
Voltage warnings: Low = 8.0–13.0V, High = 13.0–16.0V, adjustable in 0.1V increments.
Backlight brightness: Adjustable from 1 (dim) to 5 (bright).
Auto record delay: 0–60 seconds.

If no input is detected for 20 seconds, the system will automatically exit back to the main display.

3. Recording Engine Runs

Recording is one of the most powerful tools in the EGT-02R EVO. It allows you to log and analyze thermal behavior and engine response over time, such as during acceleration tests or full-throttle passes.

To Begin Recording:

From the main screen, press both buttons together to enter the recording mode.
Press the Left button once to begin recording. The “REC” icon will appear and begin blinking.
To stop the recording, press the Left button again. The data is now stored.

You can record up to 50 sessions, each lasting up to 99 minutes and 59 seconds.

4. Clearing Recorded Data

If you need to wipe all previous logs:

While in the recording screen, hold the Left button for 3 seconds.
The gauge will enter a confirmation screen.
Wait a few seconds to complete the data clearing or press either button for 3 seconds to cancel.

5. Playback Mode

Playback is especially useful for reviewing engine behavior after test runs or races. It allows you to rewatch EGT and RPM fluctuations and assess the effectiveness of tuning adjustments.

To Enter Playback Mode:

From the recording screen, press both buttons again to enter playback.
Use the Left button to select the run you want to view.
Use the Right button to control playback speed. Options include:
- 1x (real-time playback)
- 3x (fast-forward)
- 1/3x (slow motion)
- Rewind

To exit playback and return to the main screen, hold the Right button for 3 seconds.

6. Viewing and Clearing Max EGT Values

During operation, the gauge automatically stores the highest recorded EGT for both channels. This is helpful for post-run analysis or spotting potential over-temp conditions that occurred too fast to catch live.

To View Max EGT:

Press the Left button from the main screen to switch from live EGT L to Max EGT L.
Press the Right button to view Max EGT R.

To Clear Max EGT:

While viewing a Max screen, hold the Left button for 3 seconds to reset the value.

This does not affect your recorded sessions—just the live memory of peak values since the last clear.

7. Using the Temperature Unit Toggle

The gauge supports both Celsius and Fahrenheit. To change the display unit:

Hold the Right button for 3 seconds from the main screen. The temperature values will switch units accordingly.

This toggle is instant and can be done at any time—no need to enter the settings menu.

8. Adjusting Backlight Brightness

To adapt the display to sunlight, shade, or night conditions, you can adjust the backlight brightness.

Enter the settings menu by holding both buttons for 3 seconds.
Scroll to the backlight option using the Left button.
Use the Right button to choose a level between 1 (dark) and 5 (bright).

This setting is stored until manually changed, ensuring consistency between sessions.

9. Visual Warnings and Alerts

The gauge will alert you with flashing values if any monitored variable exceeds your preset threshold:

If EGT Left or Right exceeds its configured limit, the temperature will blink.
If voltage rises above or drops below its set limits, the voltage readout will flash.

These visual warnings are essential for real-time awareness during operation, especially under high load or prolonged throttle.

10. Practical Tips for Use

Always check Max EGT after a full-throttle pass. High temps can indicate lean conditions or timing issues.
Use the data logging feature to compare before-and-after results when making tuning changes (e.g., jetting, ignition).
Set voltage alerts conservatively if you're using older batteries or race-specific electrical systems.
Toggle between °F and °C depending on your familiarity or team standard.

The Koso EGT-02R EVO is not just a readout—it’s a performance tuning and engine protection tool. By understanding and leveraging its features, you can gain deep insights into your engine’s thermal behavior, identify hidden issues before they become expensive failures, and extract maximum performance under safe conditions.

Whether you're logging data after every race lap or monitoring for safe cruising, this gauge offers real-time, accurate feedback that supports confident tuning and operation.

Koso EGT-02R EVO Dash Manual - Free Download PDF User Guide