KTM 350 XC-F Performance Modification Project | Cycle World

Weekend Warrior: Modding KTM’s 350 XC-F For More Brap

Stretching out the fun factor for everyone

If you’ve ever been to an off-road race in America, or around the world for that matter, you’ve likely seen the impact that KTM has in the discipline. Over the past few years, no other manufacturer has dished out the support for the market segment quite like KTM has. And because of this—as well as the tried and true performance of KTM machines—one of the Austrian company’s most popular bikes is the widely successful 350 XC-F.

Trail riding on the weekends or racing off-road are two of our favorite activities. There’s nothing better than getting lost with buddies or banging bars through the trees or open desert. Based on KTM’s 350 SX-F motocross machine, the XC-F is a favorite among test riders for its solid handling, excellent power plant, and reliability. And since its introduction, the 350 XC-F has remained a top contender in both the serious racing and weekend warrior demographics.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

But no matter how good a bike is, serious racers—looking to gain any edge possible—often apply copious amounts of modifications to their machines, which often makes a bike better suited for go-for-broke racing than leisure. With most things in life, it’s difficult to find a middle ground, but by performing targeted modifications to the 350 XC-F, we not only maintained its bulletproof trail worthiness for the everyday rider, but also gave it more performance for a serious racer.

Due to the fact that the stock bike already had numerous hours on it prior to the build, internal engine mods were performed primarily for maintenance with just a few aimed at improving performance. A complete top-end overhaul was done and an OEM-quality Vertex piston was installed, increasing the compression ratio from 14:1 to 15:1 while still retaining the same level of durability as the OEM CP piston. The increase in compression is aimed at giving the bike better throttle response and an improved hit down low, more similar to a 450. The stock clutch plates and springs were replaced with a complete OEM-spec kit from Hinson. To add race-ready performance, a programmable Vertex ignition was installed, which is designed to improve the power delivery, by providing a smoother, yet controllable output.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

More importantly, the ignition offers two maps—aggressive and smooth—that can be toggled between, on the fly, for varying trail conditions. Aggressive for loamy conditions where traction is plentiful, or more power is needed, and smooth when the trail is hard-pack and difficult to get the power to the ground. Lastly, an aluminum/stainless FMF RCT 4.1 exhaust system was bolted on to enhance the power characteristics by broadening the power curve in both ignition positions, giving the bike a healthy low-end hit and better top-end over-rev.

To help the suspension hold up under high-speed race conditions, as well as still be supple enough for trail riding, Race Tech re-valved and re-built the suspension. In addition to valving changes, RT swapped out the 4CS fork components for its more traditional internal kit, which put the rebound clicker on the top and compression on the bottom of each fork leg, making clicker adjustments easier. Overall, the changes were aimed at improving the initial fork action and bottoming resistance. A good trail bike is supple, while a good race bike needs to hold up to hard, high-speed hits without bottoming. Additional aspects of the bike were modified with bolt-on accessories from companies such as Cycra, Renthal, IMS, Works Connection, and Tusk Off-Road—to name a few.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

Testing 1, 2, 3

Our main testing day was done at a private off-road playground complete with tight single track, rolling boulder fields, and wide-open roads. It was the perfect location to let the modified 350 XC-F stretch its legs. After our first short off-road loop, we were immediately impressed with the direction of the changes that were made. The Race Tech suspension modifications did exactly what RT intended, making for a ride that was supple on small chops, yet held up to hard hits. The initial stroke of the WPS 4CS fork soaked up slow speed bumps in a smooth non-jarring manner, making it easier to ride the bike for long periods of time.

Conversely, when hitting big g-outs or hard hits at speed, both the fork and shock held up well, using the entire stroke without harshly bottoming. Simply put, the suspension didn’t beat us up, and allowed for a more enjoyable ride whether we were charging down the trail or enjoying the views.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

Having a bike that has enough hit on the bottom without ripping your arms off the bars is important for off-road. And while the 350 XC-F is praised for its easy-to-ride power delivery—usually likened to a cross between a 250 and 450—the minor motor mods gave the 350 XC-F an even broader powerband, and a bit more grunt down low. At the initial crack of the throttle, the power was instant, yet controllable, as it came on strong, leading gradually into a healthy top-end pull that could only truly be appreciated on high-speed sections.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

The two-map ignition was probably our favorite addition, though, as it allowed us to mellow out the power where traction was lacking, and easily switch to an aggressive map when the dirt was loamy or a power-robbing hill climb was in sight. Each map made a noticeable difference in the power characteristics of the bike, and an evident improvement over stock; ‘aggressive’ hit harder and revved quicker, while ‘smooth’ was mellow, but still gradually built to a surprisingly impressive over-rev.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

Some of the modifications were done to simply make life easier on the trail or in racing situations. The small handlebar light, which is powered by a hidden battery, can do wonders for any rider if they’ve found themselves on the trail after dark. It’s small enough, though, that it wouldn’t get in the way while racing. For tight slow-speed situations, the radiators were equipped with a cooling fan, which helps push more air over the radiators. We did find, though, that if it’s left running while the bike isn’t, the starter battery gets drained, forcing a bump start.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

The Result?

Our time aboard the 350 XC-F project bike has yielded nothing but smiles. It’s usually difficult to build a bike that can perform both in competition and leisure, but with the right modifications, we’ve found that the 350 XC-F can do both. Targeted performance enhancements produced a bike that can be competitive in a face-paced racing environment, as well as a leisurely weekend trip to the local trails. As nimble and quick as it is trail worthy, the improvements have produced an off-road bike that can do just about anything.

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

PARTS COST
Vertex Piston Kit $253.58
FMF RCT 4.1 Exhaust System $874.99
Cometic Top-End Gasket Kit $60.84
IMS Over-Sized Fuel Tank $274.95
Cycra Plastic Kit $219.99
Cycra Full Combat Skid Plate $129.95
Cycra Pro-Bend Wrap Around Handguards $49.95
Uni Air Filter $28.98
Renthal 604 Fat Bars $89.95
Renthal Tacky Grips $19.95
Renthal 14T Front Sprocket $35.95
Renthal 52T Rear Sprocket $69.95
Renthal Brake Pads (Front/Rear) $34.95 (per set)
Dunlop Tires (Front/Rear) Contact local dealership
Moto Seat $59.95
Attack Custom Graphics Kit $134.99
Works Connection Brake Caps Front/Rear $27.50/$24.95
Works Connection Rotating Lever Clamp $27.50
Works Connection Oil Filter Cover $49.95
Works Connection Hour Meter $44.95
Hinson Clutch Plate/Spring Kit $199.99
Hinson Clutch Cover $169.99
Tusk Wheel Set $549.99-$569.99
Tusk Over-Sized Front Brake Rotor/Bracket $119.99
Tusk Rear Brake Rotor $59.99
Tusk Brake Rotor Bolt Kit $4.99
Tusk Lightweight Battery $79.99
Race Tech Suspension 4CS Rebuild/Valving $1,170
Pro Moto Billet Linkage Guard $299.95
Vortex/Twisted Development Ignition $749.00
Scar Titanium Footpegs $371.66
TM Designs Slide And Guide Chain Guide Kit $114.95
Trail Tech Radiator Fan And Guards $299.95
Trail Tech Custom Head Light $139.95
Rocky Mountain ATV Misc OEM parts (Pricing Varies)
Bullet Proof Designs Swingarm Guard $27.95
ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

ktm 350 xc f

KTM 350 XC-F

Jeff Allen

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