TJ Koyen piloting his KA100 package at the USPKS opener at GoPro Motorplex (Photo: uspks.com)

TJ Koyen (Photo: Kathy Churchill)

The following is a column from veteran racer TJ Koyen as he was among those to compete in the first United States Pro Kart Series KA100 category at the series opener at the GoPro Motorplex in Mooresville, North Carolina. This is his first-hand experience with the new IAME 100cc engine package.

Like many drivers in my age bracket, I grew up racing in the Yamaha class; a tried-and-true engine with a steady history of providing close and relatively cost-effective competition to the masses. From club level, all the way up to the top national series in North America, the Yamaha engine and it’s various exhaust and clutch configurations have been an icon in the sport for many years. However, as is the case with nearly every engine package karting has seen over the years, the time in the limelight is finite.

I started racing in what’s now called the Yamaha Rookie class, back in 2002. From there, I ascended to the various Yamaha Junior classes, and eventually got behind the wheel (equipped with carb trigger) of the old Yamaha Senior “pipe” class. I’ve raced the engine in almost every guise available over the past decade and a half, and as recently as 2015, I was still pounding around in the Yamaha Pro category. Though the racing has always been close in these classes, there were little issues that never really wormed their way into our minds until we started seeing new engines that addressed said issues. Clutch maintenance has always been something Yamaha drivers just accepted. There are also the “magic” engines with perfect cylinders, and contrastingly, the engines that just don’t seem to measure up.

The Yamaha formula, as it sits in most series, is also a bit on the slow side, especially compared to its senior class peer, 125cc TaG engines. It seems maybe these little perturbances were finally starting to wear on drivers, especially at a national level. Though the regional support remains strong, the United States Pro Kart Series was having a hard time justifying the class at the end of 2016, as it drew a dismal five entries at the final event. If you want national level competition, but aren’t interested in running Yamaha or spending on the extra dollars on an X30 package, what do you race?

Enter the IAME KA100.

The KA100 started in Australia to address similar issues they were having with their Yamaha fields. They’ve seen strong entry numbers in this class and have been working out the initial KA100 issues there for a little over a year now. IAME was eager to push this class in United States as well, and it just so happens it fit right into the niche USPKS was trying to fill with a replacement for the Yamaha class.

There is a lot of initial skepticism with a new engine package, and for good reason too. We’ve seen many engines come and go, leaving people hung out to dry after spending hundreds or thousands of dollars on a new setup only to see the class fade as quickly as it came. But very rarely do we get such strong support from a manufacturer as we have seen early into this KA100 program.

Personally, I wasn’t planning to race at all this year. I was hoping to save some money and get my fill of the kart track by serving as driver coach/mechanic. But IAME and USPKS came together to offer a very lucrative package for racers willing to put their necks out and give this new Yamaha replacement a try. By offering a FREE engine package to anyone who entered for the whole USPKS season, they all but guaranteed a strong field. And we racers know that the primary hurdle to overcome in a new class is getting the entries. Hats off to those two organizations for understanding this and pulling out of their own pockets to help the racer in this situation. If it weren’t for this engine offer, I know I wouldn’t personally be racing.

Our inaugural run-in with the KA100 was a shakedown session at Concept Haulers Motor Speedway in Norway, IL. This was my first chance to see the engine package put together. The air-cooled 100cc engine looks like the old air-cooled monsters of yesteryear, with the angled cooling fins and a large exhaust pipe. I couldn’t help but feel a twinge of nostalgia, remembering the HPV/Komet engines I enjoyed so much several years ago. Flanking the seat, you have a battery box and electronic start. The purist in me doesn’t care for these luxuries. I would prefer an external starter, or in an ideal world, direct-drive. But, such is the state of karting these days. The convenience of on-board starters is undeniable and it makes the class much more palatable for a lot of racers.

KA100 in full race mode mounted to the ride for Xander Clements

The clutch is the same as the X30 which means it is not adjustable and shouldn’t require much maintenance over the course of its life. Add in a squarish airbox hooked up to the Tillotson carb to feed the reedcage, and that’s basically the package. It’s simplicity is refreshing, especially after spending a year driving in X30. My first impression of the engine on-track were also one of simplicity. The KA fired up immediately from the on-board starter and I found the engine was great fun to drive, and with plenty of bottom end torque, it never seemed short on grunt; a welcome change from the bogging issues on the old HPV/Komet or the ear-splitting whine of a Yamaha slipping its clutch. After logging many trouble-free laps at CHMS, we were ready for the opening round of USPKS; the Carolina Grand Prix at GoPro Motorplex.

Our opening practice day went off without a hitch. The engine performed strongly and the MG Red tires were perfectly suited to the power at hand. I discussed with several other drivers, and we all agreed that with the slightly harder tire, but the slightly slower KA, we were driving it very similar to how we would drive an X30 on MG Yellows. The braking zones were similar, and the kart really felt very chuck-able around the smooth and fast Motorplex. The power band was good and smooth, and it felt like I had plenty of go in the right pedal whenever I wanted it. I would describe the driving experience like an HPV/Komet, but without the lack of power on the bottom end. Unlike a Yamaha, it wasn’t going to be a game of draft passes and smooth overtakes. There would be a little pizzazz in the battles.

On Friday we rebuilt our carb as a general precaution and ended up with the only engine-related issue we encountered all weekend. During the rebuild, we somehow mixed up the two carb needles, which proved to be our undoing for the early Saturday sessions. Unlike the very similar X30 carb needles, the KA needles are different pitch between them. Which means if you mix them up, your carb settings will be very far off from where they should be. This gave us a super rich condition most of Saturday morning which we couldn’t pinpoint, until we stumbled across this detail. Word to the wise; don’t swap the carb needles!

KA100 was the largest class at the USPKS opener at GoPro Motorplex in April (Photo: uspks.com)

With that little issue taken care of, we enjoyed a trouble-free weekend for the rest of the event. It became very evident on Saturday that the racing was going to be very tight. The field was unbelievably close, as the top-10 were within a tenth or two on lap times. I put this down to the tight tolerances IAME has achieved in the manufacturing of this engine. Unlike the Yamaha, the engines are all incredibly close and a stock engine can compete just as well with a “built” engine. This should eliminate the “magic” engines that plagued the Yamaha class. This meant that the front pack of drivers were often nose-to-tail and provided a ton of intensity over the course of the race. Anyone in the top ten had a shot at the victory.

One factor that came into play was drivers’ skill at tuning the carb on the fly. Much like its visual brother, the HPV/Komet, the KA100 needed attention on the carb over the course of the race to optimize the fuel mixture. I liked this. It put some of that performance and engine knowledge back in the driver’s hands. I don’t know many younger kids that know how to tune a carb on-track anymore, so it’s a nice skill to see come back into the fore.  I also noticed the on-board starter worked flawlessly all weekend. Starters are a sore subject for many of my fellow TaG racers, as we’ve often seen them fail at the most inopportune times on other engine packages. However, I’m happy to report that not only did mine last through the weekend just fine, but the engine fired up almost immediately every time I hit the button.

The battles were super close and really fun all weekend, and with 28 entries, KA100 was the most exciting class that weekend. I enjoyed myself a lot, and though was slightly disappointed to only grab a 6th on both days, I had a blast driving the engine package and racing so closely with a bunch of great drivers. My initial impressions of the class as a whole are good. I’m hoping it continues to show growth and provide strong racing. It addresses many of the issues that Yamaha had, and hands drivers a little more speed and simplicity to boot. If it continues to perform well, I think it will nobly accept the title as Yamaha’s replacement at a national level.

Yamaha has a place in North American karting, but it is increasingly becoming a regional and club level class. The Route 66 Series still is showing strong Yamaha Senior numbers, so it will be interesting to see how the KA100 package plays out next year and if it has a chance to make an appearance in regional competition as well. I am looking forward to the remaining USPKS races this year and who knows, maybe if things go well, I will have to postpone my retirement for another season and sign up to run KA100 again next year.

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