Project 2017 KTM 250EXC: The Power

After 24 hours’ run-time, here’s what we’ve learned about the character of this all-new machine’s power delivery…

Yes, the chassis and suspension components are completely new on KTM’s 2017 enduro models, but it’s the new-generation two-stroke engine that is the standout feature of the 2017 250EXC. Why? Well, aside from delivering stronger, broader and more rideable power, the first-time addition of a counter-balancer has reduced their vibration by a staggering 50%! When you twist the throttle on one of these new two-strokes for the first time, it’s difficult to process just how different they feel to ride. They still sound like a two-stroke, but the lack of vibration tells your hands, feet and arse otherwise. It’s a super-refined, almost otherworldly sensation. Instead of being overwhelmed by a teeth-rattling screech, your senses are suddenly freed up to tune into where you are in the rev range and how the chassis is behaving beneath you. That makes you feel less of a passenger, and much more in control. And when you jump back aboard an older model Kato after riding one of these 2017 bikes, it’s like travelling way back in time! Meanwhile, the addition of the Mikuni carburettor and overhauled power-valve mechanism (with lateral booster ports) to the 2017 250EXC helps make this landmark new engine’s delivery super-smooth and even more tractable than its already class-leading predecessor.

So, what have we learnt after putting 24 hours’ run-time on our 250EXC project bike? Well, depending on which dealer you purchase a 2017 two-stroke KTM through, it’s clear that the standard jetting specs are likely to be rich out of the box. With help from the guys at Australia’s largest KTM dealer, KTM Newcastle, and the technical staff from KTM Australia, we have developed a jetting spec that is significantly leaner. It creates much smoother and more progressive throttle response, and increases fuel range by 40% (from 80km to 110km) on the 2017 two-strokes’ 9.5L tank. We’re across the fact that several 2017-model 250 and 300EXC owners are now retro-fitting a Keihin PWR-38 carb to their bikes with good results, but we plan to persist with refining the Mikuni’s settings for the time being.

For even more control over the bike’s power delivery, we also fitted a Map-Selector Switch from KTM’s PowerParts catalogue. This gives you the option to choose between the standard ignition curve or a less aggressive setting – which has proven to really come in handy on slick hillclimbs and tricky off-camber corners, where you want smoother and more manageable power. The switch is super-easy to fit – all you have to do is clamp it on the bars and plug the connectors into the pre-existing plugs tucked away under the tank. And for $180, we reckon it’s a bolt-on well worth investing in.

For everyone who’s been sticking the boot into KTM for years (and Husqvarna for the past three years) about their clunky, old-school and sometimes temperamental electric-starter, you’ll be pleased to know the 2017 machines come equipped with the all-new Mitsuba starter motor cleverly integrated into the underside of the engine cases. The button (now charged by a new lightweight but powerful Lithium-Ion battery) fires these 2017-model dingers into life – first time, every time – with noticeably more verve.