2018 KTM 350 SX-F vs. 2018 Kawasaki KX450F | Dirt Rider

2018 KTM 350 SX-F vs. 2018 Kawasaki KX450F

Showdown: Two Motocross Bikes

Broc Kawi Berm Blast

The 2018 Kawasaki KX450F has a smooth, linear powerband.

Sean Klinger

The 2018 KTM 350 SX-F receives many of the changes that were made to the 2017 Factory Edition models. The WP AER 48 fork gets a new piston material, new fork seal slider, and new valving. In the rear of the bike, the shock has new damping settings. Other updates include new radiator guards, new clutch plates, a new C4 bearing in the transmission, and a new lithium-ion battery.

The 2018 Kawasaki KX450F is essentially the same as last year’s model save for the new radiator shroud graphics.

2018 Kawasaki KX450F versus 2018 KTM 350 SX-F

Showdown of the 2018 Kawasaki KX450F versus 2018 KTM 350 SX-F

Sean Klinger

Here’s what our test riders had to say after a full day of testing at SoCal’s Pala Raceway:

Andrew Oldar, Age: 25, 5’10”, 130 lb., Novice

The Kawasaki KX450F engine feels extremely linear with no surprises throughout the entire rpm range. I think it could benefit from a slightly stronger bottom-end hit to make it feel even more so, but this is mostly noticeable when the conditions are deep and loamy, mostly at the beginning of the day. Changing to the white (aggressive) coupler helps this, but only minimally. Because of how linear the power builds, I find it very easy to ride and easy to calculate how much throttle to give it to clear jumps. The Kawasaki engine sounds and feels like it runs a little lean, almost like it would benefit from a richer map.

Broc KTM 350 SX-F whip

The KTM 350 SX-F feels a lot like a 250F in many ways, two of which are that it feels light and flickable.

Sean Klinger

The 2018 KTM 350 SX-F has a smooth powerband similar to a 250F. It has a relatively soft-hitting low-end and midrange power character, while the top-end and over-rev are where the meat of the powerband is. The bike revs high like a 250F and the extra 100cc of power combined with its strength in the upper rpm makes it feel more like a 450 when the throttle is twisted to the stop. The bike is more fun to ride when you’re hard on the throttle, and it almost requires you to ride aggressively if you want to go fast. The 350 SX-F works great on more wide-open, faster tracks, but for tight and more technical tracks with jumps right out of corners, I would like to have more bottom-end grunt and a stronger pull in the midrange.

Kawasaki KX450F racing test

The Kawasaki KX450F doesn’t lean into corners as easily as the KTM 350 SX-F.

Sean Klinger

The suspension on the Kawasaki is an area where I feel green could make a large improvement—most notably the fork. The Showa Triple Air Chamber (TAC) fork seems like overkill to me, beginning with setting it up in the morning when you arrive at the track. Checking three air chambers in the fork is overkill in my opinion, especially when it doesn’t feel great in comparison to other forks. I set the fork to the stock air pressures in each of the three chambers and adjust the clickers from there. Adjusting the clickers certainly helps, but the overall feel of the fork remains, just to lesser of an extent. I tried going to the three softer air pressure settings the owner’s manual recommended, but it was a bit too soft for my liking and seemed to ride too low in the stroke. Unlike the fork, I am a big fan of the shock as it feels plush and stays planted at high speeds and in the choppy terrain.

The WP AER 48 fork on the KTM feels a lot plusher than the Showa TAC fork on the Kawasaki. Setting the fork air pressure to the stock setting and adjusting the clickers proved to work just fine for me. The fork feels progressive with a nice plush ride higher in the stroke while maintaining good bottoming resistance on bigger impacts. It’s unquestionably my favorite air fork because it almost doesn’t feel like an air fork. The WP rear shock feels like it settles very well into corners and connects nicely with the ground.

2017 KTM 350SX-F

The 350 SX-F corners very intuitively.

Sean Klinger

The chassis and handling of the Kawasaki KX450F are good in most areas. As far as straight-line stability, the Kawasaki is hard to beat. It is very predictable and is easy to feel confident when charging down a straightaway. It isn’t as easy to lean into corners as the KTM though. I feel like I have to put more effort in setting up for corners and getting the bike to lay over. Once in the corner, it gets better but still requires more effort. The skinny radiator shrouds, number plates, and seat are all very thin feeling, which I like a lot. It’s super easy to move around on and I never feel like I’m inhibited when transferring my weight forward or back.

The KTM 350 SX-F chassis feels small and light, almost like a 250F. I feel like I can put it where I want it much easier than the KX450F, and it turns more intuitively than the Kawasaki too. Straight-line stability on the 350 SX-F is good but not quite as impressive as the KX450F. The radiator shrouds feel like they get a bit wide near the front and is pretty noticeable, especially in comparison to the Kawasaki.

Kawasaki KX450F jump in air

The Showa Triple Air Chamber (TAC) fork is the Kawasaki’s biggest drawback.

Sean Klinger

If I were to pick one of these bikes to own and race, I would choose the Kawasaki KX450F because it has more overall power, is more stable, and is easier to be consistent on. Each of these qualities makes it a better racebike in my opinion. The KTM 350 SX-F is a blast to ride. It feels light, corners well, and doesn’t wear me out as much as the KX450F, but it doesn’t have the overall power or snap out of the bottom-end that I look for in a bike that would race in the 450 and/or open class. If I were to pick a bike to ride motocross, off-road, and use as a playbike, I would pick the KTM 350 SX-F hands down. It’s an awesome machine that has strengths in different areas than the Kawasaki, just not all of the ones I look for in a racebike for motocross.

Michael Wicker, Age: 19, 5’9”, 140 lb., Intermediate

Prior to testing the new 2018 KTM 350 SX-F and 2018 Kawasaki KX450F at Pala Raceway, I had not ridden either bike, so I was eager to see how they would perform and suit my riding style.

Wicker KTM 350 SF-X

The WP AER 48 fork is better than ever.

Sean Klinger

The initial feel I got from the KX450F from the first moment I got on was how comfortable it was. The seat, bar, and the subframe especially stood out to me. I have always been a fan of thinner, more agile bikes, and the Kawasaki did not disappoint in that area. The chassis had a very nice flickable feel and was very nimble through the rough bumps and edges on the track. The braking was really good on this bike: smooth and powerful. The shifting was really consistent and I didn't miss any shifts, which made it easy to prepare for corners and jumps. Overall, the shape and design of the Kawasaki were very nice and comfortable to me.

The KTM 350 SX-F was also thin and comfortable. What really stood out to me was the steel frame and how light it felt. I really liked the feel of the KTM chassis. Although I felt it was a harder transition from the usual aluminum frames I am used to on the Japanese bikes, especially when jumping and cornering. It had a vague feel on both of these obstacles, mainly in the front of the bike. I'm not sure what might be responsible for it, but it could possibly be the chassis or the weight of the bike. The throttle pull was very light and I really enjoyed the hydraulic clutch as it felt much smoother and it was easier on the arms too. One thing I noticed about the chassis is that I couldn't really get too far forward on the bike. I feel like the gas tank and shroud design keeps you further back on the seat, which was something I struggled to find comfort in.

KX450F dirt track test

The KX450F is easy to throw around in the air with little effort.

Sean Klinger

The power of the KX450F was balanced and more on the mellow side. Its overall power output wasn't too impressive, but it was still smooth and controllable. I feel this bike would cater more to those who are new to riding as well as lighter riders—not so much to racers. I think the Kawi could use an increase in overall power, especially on the top-end.

Comparing the 350 SX-F to the KX450F was a little tricky for me. This was mainly because of the 100cc displacement difference, so I focused more on how this bike built its power. The KTM has a broad and powerful engine. It is smooth on the bottom-end, but I noticed the orange bike performed the best when the rpm were up, which makes it more suitable for an aggressive rider. I personally liked the initial power curve of the 350 SX-F, but the amount of power was not comparable to the KX450F. The way the power is delivered on the KTM is more preferable to me though.

Suspension was also hard for me to compare. Both the KTM and Kawasaki have air forks, which I personally don't feel comfortable on overall. The two did offer a different feel with the different fork designs. The Kawasaki was a little harder to set up for me, especially with the Showa Triple Air Chamber (TAC) fork. Once I got it set, we were able to tweak the bike more to where I felt comfortable on it. The shock wasn't the best. I feel the shock is suited more for heavier and aggressive riders. I also struggled with the Kawasaki wanting to stand up on me in the corners and not handling how I would like it to in rougher terrain. I did notice it was a little plusher than the KTM when landing from bigger jumps.

KTM 350 SX-F Wheelie

The 350 SX-F doesn’t have the hardest hitting bottom-end or midrange power. The meat of the powerband is in the top-end.

Sean Klinger

The WP suspension on the KTM felt better and easier to handle overall for me. Cornering and really rough terrain were more comfortable on the KTM, and the suspension was also easier to set up. The shock was plusher than the Kawasaki and it absorbed the jump landings and bumps really well. I feel both KTM and Kawasaki would benefit from getting rid of the air forks seeing as they are mainly favored by the professional racer and not so much by the average consumer.

The design of the KTM 350 SX-F is perfect for those who race. It’s great on power, incredibly light, and very nimble. The hydraulic clutch is hard to beat and the chassis has a great feel. The Kawasaki KX450F is good for the average rider who is looking for a comfortable feel as well as more relaxed power. I’d prefer the KTM on a more-open track that would give it time to build rpm and so I could be more aggressive in rougher terrain. The Kawasaki would be nice on a tighter and more technical track, seeing its overall power is faster than the KTM and its suspension is a little plusher on big jump landings.

All in all, I preferred the KTM 350 SX-F, mainly for its power delivery, suspension, and nimbleness. It's just more of the style I like in a bike and it was easier for me to get comfortable on than the KX450F. I loved the comfort of the KX450F, but I prefer a more aggressive bike that I can be more loose on. Both bikes overall are strong and enjoyable to ride, but the opposing style of the two is what made me pick the KTM 350 SX-F. Sean Klinger, Age: 31, 5’8”, 215 lb., Vet Novice

KX450F test wheelie

The straight-line stability of the KX450F is unbeatable.

Sean Klinger

I honestly thought the KTM was going to be my pick, but after riding them back to back, I was having more fun on the KX. This is strange because I’m more of a 250F guy. I think the reason was that the power on the KX, especially compared to the KTM, was more exciting. And I could be incredibly lazy and still have fun. And there isn’t such a huge handling/weight-feel penalty between the two bikes.

The KTM does feel lighter and more agile, but not as much as a 250, so there is less of a gap. The 350 SX-F, when ridden with the KX450F, seems more of a vet bike for just having fun on and not serious racing. That being said, I could probably hold on to the 350 for a longer day of riding and not be nearly as worn out, but on the day we tested both bikes, I liked the KX450F. I think since I hadn’t ridden at the track in a long time, I wasn’t in the mode where I wanted to shift a ton and wring the bike out, which is what you have to do with the 350 to go fast. On the KX, you can click into third and blip over any of the jumps on the vet track with no problems.

On a side note, I think the Kawasaki, along with last year’s model, has a more responsible sound output.

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