REVIEWED: KO Propo EX-RR [Radio Test]

REVIEWED: KO Propo EX-RR [Radio Test]

Premium control for precise, pro-grade performance.
Ask even casual RC fans to name an all-time great racer, and you can bet they’ve heard of Masami Hirosaka. He’s a 14-time IFMAR World Champion with titles for 2WD and 4WD electric off-road and 1/12 and 1/10 on-road, and drives faster with toes than most of us can with our fingers. Masami’s skills are legendary, but equipment counts too, and he’s been a KO Propo guy since the beginning. While never as widely distributed in the US as big names like Futaba, Airtronics (Sanwa), and later Spektrum, KO has always been a sought-after premium brand. And with much better distribution today (my tester came from, it’s easier than ever to get your hands on a KO.

RC Car Action - RC Cars & Trucks | REVIEWED: KO Propo EX-RR [Radio Test]

KO has long been known for distinctive styling, and nothing else looks like the KO EX-RR.

KO Propo EX-RR - standard wheel

Above: If you prefer a “standard” wheel position, the factory-installed drop-down unit can be removed.

KO Propo EX-RR - adjustable wheel travel

Even wheel travel is adjustable, via a pair of screw stops behind the wheel. Trick.

For this review, I’ve got the top of the line EX-RR. This pro-grade pistol is highly configurable thanks to KO’s K.I.Y. (Kustomize It Yourself) system, and it’s got all the software adjustability you’d expect of a professional radio system.

KO Propo EX-RR - Specs and Features

KO Propo EX-RR - Kustomize It Yourself

In keeping with KO’s K.I.Y. (Kustomize It Yourself) system, the EX-RR separates into three components: grip unit, master unit, and wheel unit.


The EX-RR has three major components: the “grip unit,” the “wheel unit,” and the “master unit.” The wheel unit arrives uninstalled, and simply plugs into the master unit. The wheel is attached to a drop-down adapter, which can be removed if you prefer a standard configuration. The grip/master/wheel units are secured by latches, so no tools are needed to remove and install them. KO offers a left-hand grip unit, multi-position wheel unit, Kyosho-Mini-Z-specific master unit, and a variety of wheels, rubber grip inserts, and triggers—they aren’t kidding when they say you can “kustomize” it yourself. Out of the box, you can adjust the EX-RR’s LCD screen angle, wheel and trigger tension, trigger fore/aft position, and the angle of the brake hoop.

Binding the transmitter and receiver went off without a hitch, and I used the included RX Mode Selector to confirm the EX-RR was in “normal” mode. Bonus for Kyosho Mini-Z racers: the EX-RR can be bound to Mini-Z MHS models.

KO Propo EX-RR - double A batteries

Four AAA batteries load into the handle like a pistol magazine.


KO Propo EX-RR - adjustments

Lots of adjustment here. The distance from the trigger to the grip (A), brake hoop position (B), and trigger tension (C) are all easily set.

KO Propo EX-RR - antenna

KO offers the EX-RR with a “long antenna” (shown) or “short antenna” KR415FHD receiver. The RX Mode Selector unit lets you switch the receiver from “normal” to High-speed Communication System mode. When used with KO Propo HCS servos, you get faster servo response time. Individual channels can be switched to HCS mode, in case your setup includes both standard and HCS servos.

KO Propo EX-RR minimalist display

The EX-RR’s minimalist display is easy to navigate and understand. Just arrow around the menu, hit ENT to select, then use the arrows to increase and decrease values. There’s even a built-in gear ratio and rollout calculator!

KO Propo EX-RR - reposition screen

With a bit of disassembly, the screen can be repositioned so it’s perpendicular to the radio body, rather than parallel.

The EX-RR is extremely easy to use when setting up essentials like steering and throttle endpoints and servo direction, which I navigated to and adjusted without consulting the manual. For deeper-level functions, such as Throttle Push, Throttle Auto-Start, and the mixes for the third and fourth channels, you’ll likely need to dig into the manual—which doesn’t offer much info. The best bet is to plug in a pair of servos, experiment with the settings, and watch what happens. If all you’re doing is setting up a car or truck with conventional steering (and you’ve got some computer radio experience), you’ll have no trouble.

RC Car Action - RC Cars & Trucks | REVIEWED: KO Propo EX-RR [Radio Test]

Driving With the EX-RR
Even before powering up the EX-RR, you can feel it’s a premium piece of equipment. It has a very nice balance, and feels like one solid piece despite the modular construction. The K.I.Y. system’s latch mechanisms pull the modules together tightly, and putting the parts together feels like you’re one of those cool guys reassembling his pistol before a big shootout in an action movie. Chick-click! The bearing-supported steering wheel is machined aluminum, and turns with just the right amount of detent at
neutral. The trigger is equally precise, and the adjustable brake hoop is really well thought out. It pivots on a ball, so you can angle it side to side, as well as closer or farther from the top of your finger.

I paired the radio with a high-speed Hitec D-series servo, and the responsiveness was incredible. Just think about making an input, and the car reacts. Range, as expected, was excellent, with full control past the point of practicality. Most EX-RR users will be track driving where range isn’t a big issue, but it’s nice to know you can go the distance. I drove with the EX-RR’s wheel in both “standard” and drop-down positions, and the radio disappeared in my hands either way. This is a pro-caliber unit that doesn’t distract you with plastickyness, poor balance, and so forth. The EX-RR lets you focus on driving, and if you’ve got the skills to win, there’s nothing here to hold you back.

The Verdict
In case you didn’t already get where this was heading, the EX-RR is a serious piece of competition-grade equipment. As such, it commands a premium price—expect to spend about $460 to put one in your pit bag. For the money, you’re getting a top-quality radio system that offers world-class precision and impressive flexibility for comfort and control. But if you’re hoping for a lot of flash in the software and display department, prepare to be underwhelmed. KO is strictly business here, and the simple LCD display assumes you’re more into watching your car on the track than the screen on your radio. It does everything
a display needs to do, just without touch capability or high-res color graphics. How much that matters is up to you, but it sure won’t keep you off the podium. —Peter Vieira

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Updated: April 8, 2018 — 4:28 PM
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