TUNED: Jay Clark's 2024 KTM 350 XC-F Project Bike

Building The Ultimate KTM 350 XC-F

Story and Photos by Trevor Hunter

When Jay Clark calls with a bike build, it usually starts with a resounding yes before we even get into the details. With decades of experience and countless bike builds under his belt, Jay has a formula and it usually culminates with a capable bike ready to tackle whatever it’s destined for. In this case, the bike started out as a 2024 KTM 350 XC-F and Jay modified it as he saw fit. Although it looks heavily modified and like a show bike, there really aren’t many “extra” mods. Internally, the motor is completely stock. Aside from a FMF exhaust system, Rekluse TorqDrive clutch, and a Vortex ECU tuned by Twisted Development, there are no big power mods aside from the KTM two-stroke screen-less filter cage and vented air box cover. Race Tech revalved the stock components, including the new XACT closed-cartridge spring fork and a stock rear shock. Dunlop Tires graced the front and rear wheels, while a host of goodies from companies Jay works with were strewn across the bike — some with function, some for looks, or both in some instances.

Power

Right off the bat, we were pleasantly impressed with the power delivery on this 350 XC-F. In stock trim, it truly is very good and so much improved over the 350’s of yesteryear. This bike has torque and it revs. The stock power revs quick and it revs far, but it does lack some torque on the bottom in comparison to a bigger 450, as expected. However, this 350cc powerplant found some of that desired torque while maintaining the stock rev happy power character that we love in the 350. Our own 350 XC-F build that we just completed was loved by some of our riders who craved more torque out of the bike, but some of riders wished for a more aggressive, quicker revving power out of it. In this case, we feel we truly have the best of both worlds as it added some torque and grunt down low, but we maintained and even improved the mid-top end from stock for a complete motor package.

There are a few factors here in regards to the power. There is the 14/49 gearing (stock is 14/47). That alone will help with the torque and building revs quicker over stock. We feel we could experiment with gearing here and possibly go taller in the rear similar to our bike. We say go up on the rear because we feel its important to keep a 14T countershaft sprock for chassis-handling purposes. It smoothens out the chassis feel and helps the bike handle better with less chain tension torque playing a factor.

In addition, the FMF system is a little unqiue in that Jay installed a 250 XC-F header instead of the 350 XC-F specific header. the 250F header is shorter in length, which is less prone to damage out on the trail, but also will boost top end and over rev in comparison to the longer 350F counterpart. Lastly, there is the Vortex ECU mapped by Twisted Development. This is something we haven’t tried in any capacity on our own 350 XC-F project bike that we just finished, so we can’t say how much of a factor this plays in how each bike’s power delivery differs, but riders who like an agressive power may want to opt for the 250F header from FMF while riders who want to utilize torque and ride taller gears may want to stick with the 350F header from FMF.

Suspension

To start, the suspension is setup for Jay who is going for a “trail” setup whereas the two riders we had on hand today were faster racers who don’t spend a ton of time on softer suspension. However, it’s quite impressive how hard we were able to push the bike with control and comfort. In the slower speed single track, the bike offered good bump absorption and comfort, tracking through the small chop without riding too low in the stroke and offering a harsh feeling. As the speeds increased, the softer nature of the suspension became more apparent. In the bigger hits on the off-road loop, we’d bottom occasionally but in a controlled manner that rebounded safely. We even took it to the vet MX track and rode the bike with ease just to see the range of versaility the Race Tech components had.

For sag, we ran the bike at 105mm and rode with the forks flush. This is something we’ve played a lot with on our test bike and on this day, we didn’t have any vague front end troubles like we occasionally experienced on ours.

Chassis-Handling

Like the motor, we were pleasantly suprised with the handling of the bike. Typical of a 350, it felt very light and nimble and that peppy power that comes with the mid-size motor only helps that feeling. As easy as it was to initiate a turn, it felt easy to stay in the turn and into the faster sections of trail without a lack of stability.

The ergos all felt spot-on with the ODI handlebar/Moto Seat/Scar Footpegs setup that retained the stock rider triangle. Dunlop’s AT82F front tire has quickly become our go-to front tire in Dunlop’s lineup, and the at82 rear tire is one of their best as well.

One of the most intriguing points on the bike was the use of a KTM 450 clutch master cylinder. It uses a 10mm piston vs a 9mm piston found on the stock 350. Jay likes the 450 style master cylinder for durability purposes as it helps reduce clutch fade in abusive situations; however, it makes for a harder pull at the lever. This stuck out to me without Jay telling me about the change, so it is noticeable. I prefer the 350 master cylinder simply for the lighter pull, but it is nice to know that there is an OEM option to help increase clutch life if you’re hard on the clutch.

At the end of the day, we were pretty impressed with Jay’s ride he built up. His bikes are always solid as he uses a lot of quality components and works with the right people. The engine character in particular was a standout for us as it improved everything on the stock motor without any negatives in what were looking for. For more on this bike, here’s a few words, as well as a parts list including the Trail Tech Radiator Fan that “doesn’t exist” for the new gen KTM’s.

Jay Clark – “For this build we kept it very simple with minimal engine mods. The engine on the new bike is great and just adding a Vortex ECU mapped from Twisted Development makes it even more amazing. The motor runs cleaner with more power and less chance of stalling. We also added a Torque Drive Rekluse clutch to help clutch durability and performance. OEM KTM 2-Stroke Filter cage without the backfire screen. We also added an FMF pipe and Race Tech took care of the stock spring forks.”

For additional clutch spring feel we upgraded the clutch master to a 10mm 450SXF set up (available directly from KTM for a 450 model).

A very custom look to our anti-orange KTM- – All new 2023.5/2024 GASGAS front end pieces and all Black shrouds and rear pieces.

Twisted Development

www.td-racing.com

ECU with custom mapping

Pro X Racing Parts

www.pro-x.com

Rear Sprocket 49T up two from stock

Front Sprocket

Gold X-Ring Race Chain