Kommander K1 TR-1 - World Exclusive

Kommander K1 TR-1   -   World Exclusive
A descent four-stroke stand-up
Kommander Industries goes one step beyond and launches a descent four-stroke stand-up ski powered by the latest Yamaha TR-1 engine, thus showing to pwc scene what the future would be like.

Words: Vasilis Moraitis
Test Rider: Vasilis Moraitis
Photos: Jetskiworld.gr and Glenn Dickinson


Four-strokes are heavy, bulky and the have more moving parts than the lightweight two-stokes however, whether we like it or not are the future. So when an Austrian company introduced the first four-stroke stand-up everyone thought that the Japanese personal watercraft manufacturers would follow soon however it never happened although both (Kawasaki and Yamaha) have been working continuously in this field. Kawasaki in the past ditched its four-stroke SX-R15F ski due to its bulky engine and huge weight while Yamaha has tested many different four-stroke projects.


When Yamaha introduced last October its new four-stroke, three-cylinder engine with the cross plane crankshaft it made a big difference to the Runabout VX performance. As the new compact, lightweight engine provided better hook-up and improved top speed remarkably. Kommander Industries had already made its arrangements and soon a complete TR-1 engine was on its premises and the crew started working on it. K1 TR-1 was on its way and Dustin Motzouris spent countless hours of testing in order to perfect the overall set up and balance of the new boat.

K1 TR-1 was the third project of a complete ski that Kommander crew practically completed a after the original K1 and S1 projects. Dustin Motzouris explains some of the key points of this new Ski however, customers should be aware of the fact that each and every one of Kommander Skis are produced by a crew which dedicated to what is doing every single day.

Which were the initial issues you experienced when you tried to fit the TR-1 engine inside the K1 engine compartment?

Dustin Motzouris: The tr1 engine will not just fit and align in a two-stroke hull , the entire mounting position , drive line angle and total weight distribution needs to change .Many people think we just fitted a motor and they can do the same , this is so far from the truth and a lot of work is needed.


Did you have to alter the hood or the deck in order to fit it inside?
Dustin Motzouris: Our original K1 hood had to be altered but our deck allows the engine with ease.

What changes did you have to make for the exhaust system?
Dustin Motzouris: We run an in hull silencer under the tray area and the exhaust outlet after the manifold is Kommander made.


How was the performance with the OEM ECU mapping?

Dustin Motzouris: The standard ECU mapping is very good but a little lean in fuel mixture.


How much was it altered after it was reflashed?
Dustin Motzouris: The power came alive after the reflash but we have just tipped the iceberg with this, there is still so much more potential.

Was it hard to match the driveline system and the impeller pitch?

Dustin Motzouris: The four-stroke makes totally different power delivery and a hand made impeller was needed. This took many hours to get correct and we are still improving.


Do you think that the boat is fast and reliable with the current set-up?

Dustin Motzouris: I feel the boat is more reliable than anything on the market. I feel  it is as reliable as a standard SuperJet.

Is there any room for improvement and what will you suggest before thinking of putting a turbo-system?
Dustin Motzouris:
e are always working and improving. Turbo will unleash unlimited power, maybe too much for stand up usage. But for now our main focus is developing a dream ski for the consumer and our main focus is cost reduction, it is an amazing ski but the only barrier to purchase is cost. We are working very hard to make it more affordable but not give up quality and the exotic nature of the ski. This is a true WORKS ski, totally factory and beautiful with excitement whenever you even start it. We don't want to loose that.

Looking at the engine compartment of the K1 TR-1 I was left speechless since everything was placed in the right position and most of all the fuel tank, the exhaust routine and the ECU unit. The later is originally mounted at the front of Yamaha’s oem air box. However, since that on was missing the ECU was mounted in a different location. The fuel tap was mounted at the right rear end of the engine compartment.


Testing in Havasu
Testing Kommander’s K1 TR-1 ski was a whole new experience since the only four-stroke skis tested by Jetskiworld.gr in the past were the race tuned S4’s. Having tested the brand new Yamaha engine on the 2016 VX a few months ago helped me a lot in terms of understanding the demands of this new stand-up since you do not ride it like a two-stroke ski.

K1 TR-1 fired up easily with no need to touch the throttle lever at all. The free-flow exhaust system and the modified induction system resulted to a magnificent sound system which is a pole of attraction. The 115+hp Yamaha powered ski was accelerating right from low rpm with no hesitation. However the most interesting feature was the massive torque at mid rpm that was translated to arm pulling acceleration. It is not scary but far more joyful to a stock S4. During its acceleration all the way to its top speed the stability of this ski was outstanding. There were absolutely to signs of nose hunting or hopping which made me think that Kommander crew carried countless hours of testing in order to alter the overall balance of this boat. Many people out there should possibly think that the new K1 TR-1 would be heavier and balkier than a three-cylinder K1. Well, according to Dustin’s figures this boat actually weighs 5 kg less than a K1 Kawasaki set up and it feels lightweight while you ride it. Speed wise, this Ski as we tested it can reach the top speed of 57-60mph consistently. Which is a very good average for a happy going medium level rider.


The ski was easy predictable when I took it round the buoy course at Body Beach. It was easy to change direction and lean it from one side to the other without upsetting the handling or the flow of my pace. Kommander crew shortened the RRP billet pole and change the throttle lever angle in order to bring it closer to my ergo standards. Compare to a two-stroke K1 I had to keep it more on the gas prior setting the ski to an arc since the pump had to be loaded in a different way. The modified (for the four-stroke application) K1 hull hooked up so nicely and kept the pump fed up constantly on exit when I was back on the gas no matter how aggressive I was in to it.


The second interesting feature of this boat is the way that the hull sucks the water under deceleration. When you let of the gas from full throttle you better hold on tight otherwise you will be surprised. That should not be an issue for the experienced rider, though. The pump tunnel sucks water so roughly that makes the hull to feel as it has been glued to the surface of the water. This enables you to brake harder, later and closer to buoy and to initiate the turn with more throttle since you have better drive already.

In general this new Ski of Kommander Industries is very interesting and promising. The only modification that was carried to the engine was the reprogrammed ECU which was carried out by Bill Chapin of R&D. At this stage you cannot called a race ski however it is a fun to ride ski that keeps you happy no matter what the water conditions are. Simply imagine how far you can go with this new engine with mild porting, cam mods and 100octane or ETS reprogrammed ECU tuning. Adding a turbo to it would be the racers answer to the modified S4’s. Definitely, someone out there is already working on it and we know that Kommander crew is not sleeping. 



Yamaha TR-1 three-cylinder, four-stroke engine.

Yamaha OEM cross-plane crankshaft

Bore and stroke: 82 x 66.2mm.

Displacement: 1051cc
Modified air induction system

OEM exhaust system with modified exhaust outlet

Fuel: pump gas, 87 octane

Cooling lines in: One line in to cylinder block

Cooling lines out: One line exit from exhaust
Rickter gas tank


Yamaha OEM TR-1 electric system

NGK BR9ES Spark Plugs
Yamaha OEM ECU reprogrammed by R&D, installed in new brackets.

Pump and driveline

Skat-Trak C 83 145mm, 14 vain, setback, with 83mm hub Magnum Pump

Skat-Trak three blade, stainless steel Swirl Impeller

Skat-Trak drop nozzle
Kommander hydraulic trim system

Reduction nozzle:83mm

Steering nozzle:88mm

Hull and Handling components
Kommander K1 with redesigned bond flange at the sides.

Overall length (mm): 2270
Overall width (mm): 750
Dry weight (kg): N.A.
Dimensions of tray (mm): 830 x 510

Kommander K1 Racing hood

Jettrim gunwale pad covers with lifters and dash cover

ADA Racing billet aluminum bypass fittings

Kommander carbon ride plate

Kommander intake grate

Rickter gas cap

Steering assembly

RRP billet aluminum handlepole

RRP chin pad

Hot Products 4 degrees handlebar

Kommander steering system

Skat-Trak heavy duty steering cable

Kommander trim lever

Skat-Trak trim cable

PJS trigger lever

ODi grips

Estimated power: 115+hp

Top speed: 58-60mph
Price of complete Ski ($): 22000usd

Kommander Industries
Phoenix, Arizona

E-mail: sales@kommanderind.com

The series of tests were carried out with the valuable help and support of Kommander Crew and R&D Performance.