NO.1 KTM 125 SX

Words: Broxy | Photos: Paul

While the humble one-twenny could be considered old hardware, the Austrian marque has set out to prove otherwise, with one of the most modern dingers that has rolled off a production line. But could it be made even better? To find out, we took a spin on the bike of the current National 125cc No.1, our very own, Ben Broad!

So, this is the current number one bike, which I got to ride.
C’mon, I had to rub that in!
But there’s more to it than that, too… this bike is also one of the easiest two-stroke one-two-fives to ride fast.
I will explain the reasons why, too.

First, here’s a little background about its pilot, Ben Broad.

My most vivid memory of Ben is the wee tyke I was coached in a one-on-one session that we did in his backyard. He had a proper track, too, so I remember thinking that he had every chance of going a long way in his chosen sport of motocross. With the passion and ability to ride after school, along with a very committed and supportive family, it comes as no surprise to see him now holding the number one plate.

Next up, let me tell you about the developer of Ben’s race bike, Mark Scobie of M-Spec Racing. He is kind of guy that you could talk dirt bikes to for days on end, and is definitely someone who knows how to get a bike performing for its rider, especially if it is a one-twenny. With Damien King as his rider, that is the class he owned in the mid-Noughties, but there were numerous successes before and after that period of racing. Obviously, Mark knows all about the importance of confidence and consistency as the key to success, which this championship being the proof.

With that, Mark built this bike with the 2016 125cc championship in mind. As Ben has muscled up, he required plenty of horsepower, but it needed to be delivered in the nicest possible way. The same goes with the suspension, which Ben prefers to run with fairly fast rebound dampening for maximum traction, yet finding the balance where it is still forgiving enough to give its rider maximum confidence.

Real Results

For this test, we found ourselves on the Pirini motocross track, which had just had some heavy rain. In all honesty, it was probably not the best condition to be testing a small two-stroke, but it was exactly what a ripped and watered national caliber track can be like. In fact, it was very similar to the round at Flipps that had deep whoops and sandy berms, which was where Ben swept all the races and started to gain the momentum he needed to get a stranglehold on the title.

Yeah, things were looking fairly bright for our test.

With the formalities out of the way, in the way of static photographs of the bike and its pilot, it was time to see what the little beast could do.
Being my first proper moto in quite some time, I wasn’t all that confident about how long I would last out on the track, completely expecting to feel like I had been run over by a truck. But, surprisingly, the laps kept ticking over and it felt like I was just starting to get warmed up.
Even though a one-twenny is pretty easy on the arms, I expected to exert more energy on both a hotted up bike and even the standard machine. When it cames to this bike, there was more to this bike than meets the eye.

It was during a chat to Mark where it all fell into place.
“I didn’t realize how linear the power is on these new one-twennies,” I said.
“No, no, no, no, no,” came the reply, and I could picture the lanky limbed, lightly bearded fellow on the other end.
“The new bikes are not normally like that – I made it that way.”
It turns out that many hours of development had gone into making the power on this bike increase with no flat spots or sudden increases… and for good reason.
“I wanted Ben to know that there would be a short period where the bikes beside him down the start straight might ease off their acceleration, while his would keep pulling, as that is the secret to building confidence.”

Obviously, this was obviously no accident.
Sure enough, in every start, Ben was in the first three.
It was this deceivingly smooth delivery that made the bike almost feel slow, even though it wasn’t, of course. Rather than being impressed with some aspect of its power, I found that it was just incredibly predictable. There was no need to worry about hitting some dip in the power delivery, as it would pull exactly wherever you ended up in the rev range, which was a good thing in these conditions.

Recipe For Success

The Flipps track is a type of sand that cuts up significantly, leaving no room for any dead spots, or you run the risk of getting kicked when the power can’t pull you out of a hole. With Ben sweeping all three races in such conditions, it’s safe to say that this moto has the power to do so, helping build the confidence to go and win.

How Mark achieved this desired characteristic is only known to him. The details that I can share about the internal work on this bike are limited, but there are a few things that current 2016 125 SX owners might like to know.
As a standard base gasket was used, along with the standard ignition, most of the changes came from the revising of the port timing and creating a computer-aided custom cut head. Despite a good deal of number crunching, this was not hard for Mark, as it is his specialty.

While all the details were good to know, it was his talk about something called the “squish band” that got me most interested.
For those unfamiliar, the squish band is a particular strip of the cylinder head that gets very close to the edges of the piston, typically less than a millimetre. This band forces the gases on the outside edge of the cylinder to “squish” towards the center that creates a kind of turbulence that promotes a better explosion. According to Mark, he narrowed this band while also tightening it up, creating an even better bang on each stroke. There was also the expected increase in compression, but as to how much, only Mark will know.
Another interesting fact is that M-Spec chose to tune it all around the combination of a Scalvini cone pipe and silencer. As the name would suggest, it is a brand that was founded by Italian man of the same name, one who is intensely involved in each type of pipe from first test to final production. His pipes are apparently well known all over the world, but aren’t too prevalent in New Zealand.
Last but not least, it was finishing off the base to work around a 50/50 mix of avgas and 98 from BP.
Despite the 2016 KTM 125 SX being so different to the previous models, all of this wasn’t too hard for Mark. But there is much more to a championship-winning bike than just smooth power, since, as we all know, handling is key.
It was the new chassis and suspension that saw Mark scrambling to find the kind of results that he had in previous years.

Long Legs

After close to three months of testing, Ben and Mark finally settled on what I was now riding. It was pleasantly firm for someone like me, sitting high in the stroke, which was especially helpful through the fast dips where any bike comes under extreme load. Where a standard bike might suffer from headshake, or at least a very heavy feeling, Ben’s bike stayed light and friendly.
The firm compression dampening and fast rebound were the secrets to that success, but I would normally expect that style of suspension to be somewhat arm pump inducing and rather unforgiving over the rises. In theory, it should struggle with slippery conditions, because of decreased suppleness. While there may have been some of that, I wasn’t feeling it.

There is something about suspension that rides high in the stroke that instills confidence. It is like writing with a sharp pencil, rather than a blunt one – your lines are crisp, exactly where you put them. That means that every patch of traction can be used to its full effect, helping a skilled rider carry more speed and lean into the turns further, all because the touch is lighter.
The fast rebound keeps the wheels in touch with the ground and the firm compression keeps it using the plusher part of the stroke more often. It all depends on the speed at which the rider can push the bike, as well as just how fit they are to handle the increased feedback there will be for the length of a race, too.

The duties of traction are taken care of by the trusty Pirelli MX2 tyres, on the front and rear, which Kiwis have been using for years. Given that it probably got fresh rubber for every round, there was never going to be any problems with running the normal pressures of 14psi in the front and 13 in the rear.
I found that Ben likes the handlebars rolled quite far back, but is happy with a more neutral position for everything else, which sees the levers just below level.
Other than the fresh No.1 on the plates, there were few other alterations that need mentioning, surprisingly.

Prize Piece

This is definitely the kind of bike that any champion would love to keep for their trophy room – not forgetting the compulsory rip ‘round the track, once or twice a year, of course!
For those who could not bear to leave such a bike parked up for so long, which would be most of us, Ben’s race bike epitomises what moto should be all about. It is fast yet forgiving, with inspiring sustainable speed, its number one representing a worthy reward for the many months of effort that both its mechanic and rider put in to achieve that goal.
Best of all it is a barrel load of gear tapping, clutch slipping, two-stroke enjoyment.
Plus, it doesn’t look too shabby either.
I had a blast riding this bike, becoming more impressed with every lap I did. It certainly required a different riding style to the 250cc four-stroke that I am used to, forcing me to resort back to the 125cc riding style that is at the true core of my being. Getting busy on the gear lever, I could now attack the braking points harder than usual, all without getting sucked into the soft berms.
The bumps never deflected my wheels and the suspension kept begging for more punishment. The cockpit felt comfortable and the bike was well balanced. Honestly, I could have ridden it all day and gotten faster with every lap.