MC Tested: Trail Tech TTO Temperature Gauge

Getting a (accurate) bearing on the KTM RC390’s engine temperature.

Trail Tech Temperature Gauge
Accurate info, updated regularly. The blue button allows you to switch between Celsius and Fahrenheit and reset the max temp.Photo: Julia LaPalme

It's no secret that KTM's spicy little RC390 runs hot. But how hot exactly? The bike's bar-graph temp gauge doesn't give you an actual number and it seems like the difference between "all's well" and "it's gonna blow" is just a bar or two, so you never really know when you're going to overheat.

To get a better bearing on the RC’s coolant temperature I turned to Trail Tech and their TTO gauges. The TTOs come in several flavors—you’ve got your hour meter, tachometer, voltmeter, and temperature gauges, and they’re all packaged in the same compact and water-resistant housing. Different internal programming and cable attachments let the TTOs serve various purposes, and you can get the gauges in black, silver, or orange so they either blend in or stand out. Depending on the accessories it comes with, kits run from $43 to $48—pretty affordable, any way you slice it.

Trail Tech Screw Sensor
The screw sensor is working well for me, but Trail Tech also offers the TTO kit with a machined-aluminum inline-hose sensor like the one picture above.Photo: Julia LaPalme

I went with black for the RC390, and went with the M6-1.0 screw-sensor option, spinning the sensor into the radiator in place of the stock bleed bolt at the top left of the RC’s radiator. Trail Tech also offers inline radiator-hose sensors (in 16mm, 19mm 22mm, and 25mm OD) plus a copper spark plug sensor for air-cooled bikes. I snaked the sensor wire up through the frame and stuck the gauge right next to the dash on the RC’s fairing stay with the included double-sided tape. The kit also comes with small bolts for permanently affixing the gauge to a flat surface.

The gauge is within my peripheral vision while riding and the digital display updates every few seconds. I don’t even bother looking at the stock temp gauge anymore, though I am curious to correlate the number of bars to an actual temperature range. The TTO is powered by an internal battery, and based on my previous experience with the gauges (as engine temp and hour meters) the battery literally lasts for years.

Now that I have an accurate means of monitoring the RC’s engine temp, I intend to perform some cooling-system tests to see what will lower the KTM’s operating temperature. Removing the radiator far (for track use), swapping coolants, and eliminating the thermostat and bypass plumbing are all mods I’m eager to try.

If you need to keep tabs on engine temperature, hours of operation, battery or electrical-system voltage, or engine speed, Trail Tech’s TTO gauges are an affordable and easy to use option.

Trail Tech TTO Temperature Gauge
PRICE: $43-$48
VERDICT: The simplest and cheapest way to get an accurate reading on your engine temp (or engine speed, battery voltage, or run time).