2019 KTM 350 EXC-F Project Bike Riding Impression

Jay Clark shows us what a modified KTM 350 dual sport bike is capable of.

Dual sport bikes are continually gaining in popularity and becoming more versatile than ever with each new model year. This is especially true with KTM’s EXC-F lineup, which includes the 350 EXC-F and 500 EXC-F. We tested both of KTM’s 2019 dual sport bikes in a comparison test and came away impressed with both of them. While the two EXC-F bikes are great, there’s no denying they come choked up in stock trim to meet EPA emission standards. This is especially true when compared to the Austrian manufacturer’s SX-F motocross bikes and XC-F off-road models.

We tested a Jay Clark-built 2019 KTM 350 EXC-F on the trails, track, and pavement at and around Cahuilla Creek MX.
We tested a Jay Clark-built 2019 KTM 350 EXC-F on the trails, track, and pavement at and around Cahuilla Creek MX.Spencer Owens

Project bike builder Jay Clark is well aware of the EXC-F engine’s limitations in stock trim and decided to modify his personal 2019 KTM 350 EXC-F to not only make it more powerful, but better suspended to be able to handle a vet-level motocross track, effectively taking it from a dual sport to what he calls a “tri-sport”—a bike that can be ridden on the road, trails, and track. Clark made it clear to us that his main focus was to make it great on the tight trails and good for connector roads—not doing long highway miles or pushing it on a higher-level motocross track. With that goal in mind, he simply wanted to go for it. With no limitations on building the best dual sport bike possible, why didn’t he start with a 500 EXC-F?

“Because what’s the fun in that?” Clark responded in jest. “The 350 EXC-F is lighter and nimbler. Also, Cylinder Works has a big-bore kit for it that makes it a 366cc, and the extra displacement combined with the other modifications give you a racebike feel on a dual sport bike.”

The KTM EXC-F models are choked up in stock trim to meet EPA emission standards. Clark uncorked his 350 EXC-F with the help of Cylinder Works, Twisted Development, and Blais Racing Services.
The KTM EXC-F models are choked up in stock trim to meet EPA emission standards. Clark uncorked his 350 EXC-F with the help of Cylinder Works, Twisted Development, and Blais Racing Services.Spencer Owens

Twisted Development built the engine and Clark told us it made more than 50 hp on the Murrieta, California-based company’s dyno. That’s impressive, especially considering the stock 2019 KTM 350 EXC-F made 34.7 hp on our dyno. Other key parts of the build were from Blais Racing and SAR Off-Road.

It wouldn’t be a Jay Clark project bike without an FMF exhaust system, a plethora of Works Connection goodies, DeCal Works graphics, and Dunlop tires.
It wouldn’t be a Jay Clark project bike without an FMF exhaust system, a plethora of Works Connection goodies, DeCal Works graphics, and Dunlop tires.Spencer Owens

“A Blais Racing 7-ounce weight was added to the clutch for better tractable power and less flame-out,” Clark explained. “SAR Off-Road makes a grip of custom plug-and-play items for the KTM EXC-Fs and they make a big difference. After a few trips on the trail, you learn about the things you want to change, and after running your battery dead a few times from keeping the key on, you will want to call them up and get their parts as they are much better for the more trail-oriented rider. Also, the switches for the lights and blinkers allow you to run the clutch perch where you would like since it’s slimmer, and the same goes for the front brake side with the starter and kill switch. The SAR blinkers were set up and tucked in, and they also included blinker relays.”

We logged some street miles on the bike, and fueled up at the gas station before hitting the track and trails.
We logged some street miles on the bike, and fueled up at the gas station before hitting the track and trails.Spencer Owens

We met Clark out at Cahuilla Creek MX, an excellent dirt bike riding facility in Anza, California, that has a main track, vet track, off-road loop, and lots of single-track trails, making it an ideal place to test his 2019 KTM 350 EXC-F “tri-sport” project bike.

To say that Clark’s project bike was an improvement over a stock 350 EXC-F would be an understatement. It had a much snappier throttle response, revved quicker, and pulled noticeably harder than a stock one. It retained the same powerband that KTM’s 350 four-stroke models are known for in that it revved very high and pulled all the way to the rev limiter. These qualities benefited not only in the dirt but also on the street, as getting up to speed when merging onto the highway from a dead stop was little trouble for the modified engine. Although Clark’s bike revved faster than stock, it retained the stock 350 EXC-F’s flywheel effect, meaning it didn’t rev as fast as an SX-F or XC-F model, but was less reluctant to stall and required less clutch work than a stock 350 EXC-F at low rpm, which furthered the dual sport’s ability to excel on the tight, single-track trails. The project bike’s engine was a night and day difference than stock, and all for the better.

Clark’s project bike had a much snappier throttle response, revved quicker, and pulled noticeably harder than a stock 350 EXC-F.
Clark’s project bike had a much snappier throttle response, revved quicker, and pulled noticeably harder than a stock 350 EXC-F.Spencer Owens

As far as the suspension, Race Tech massaged the components with a revalve and setup of the WP Xplor 48 fork and WP Xplor PDS shock. Both ends offered a firmer feel throughout the stroke, which made pushing the bike on the single-track and more wide-open off-road areas of Cahuilla Creek MX confidence inspiring due to the WP units’ better hold-up. In lower-speed areas, comfort was decreased just slightly, but the tradeoff for the increased predictability on higher-speed impacts and better bottoming control was worth it. Despite being stiffer than stock, the suspension was understandably a little soft for the vet track, but that only became apparent if I came up short on a jump or overjumped out to flat. So long as I downsided the jumps, the suspension held up just fine. On the opposite end of the spectrum, comfort on acceleration and braking bumps was very good too.

The Race Tech-massaged WP Xplor 48 fork and WP Xplor PDS shock offered a firmer feel throughout the stroke, which made pushing the bike on the single-track and more wide-open off-road areas of Cahuilla Creek MX confidence inspiring due to the WP units’ better hold-up.
The Race Tech-massaged WP Xplor 48 fork and WP Xplor PDS shock offered a firmer feel throughout the stroke, which made pushing the bike on the single-track and more wide-open off-road areas of Cahuilla Creek MX confidence inspiring due to the WP units’ better hold-up.Spencer Owens

Like KTM’s motocross and off-road models, the 350 EXC-F has a neutral-handling chassis that makes it both fun and easy to ride. With its more aggressive engine character and firmer suspension, Clark’s project bike reacted quickly yet predictably on the trails and the track. The EXC-F has comfortable ergonomics in stock trim, which were complemented by the plethora of aftermarket components Clark added to the bike. Among the most noticeable were the Renthal 603 Fatbar, which had an agreeable bend, along with the MotoSeat seat cover that offered some additional grip over the standard component and the Scar Racing titanium footpegs, which provided a larger platform and more grips than the stock unit as well. Finally, Clark’s use of a single Double Take Enduro mirror worked great while riding on the street and was easily able to fold down near the bar pad so that it was out of the way while riding off-road and moto.

Gearbox

Despite being stiffer than stock, the suspension was understandably a little soft for the vet track, but that only became apparent when coming up short on a jump or when overjumping to flat.
Despite being stiffer than stock, the suspension was understandably a little soft for the vet track, but that only became apparent when coming up short on a jump or when overjumping to flat.Spencer Owens

Parts List

Clark did a superb job of making his KTM 350 EXC-F more capable and fun to ride, both in the dirt and on the pavement.
Clark did a superb job of making his KTM 350 EXC-F more capable and fun to ride, both in the dirt and on the pavement.Spencer Owens

SAR Off-Road

LED taillight

License plate mounting plate

LED turn signals with OE-style connector (front and rear)

Smart flasher LED turn signal relay

Direct plug-in dash indicator rewire kit

Key switch eliminator

Over/under start/stop switch

SAR keyed kill switch

Multifunction light control switch with off, low, and high settings

Cylinder Works

366cc big-bore kit (includes forged Vertex piston and top-end gasket kit)

Twisted Development

Vortex X-10 ECU

Custom ECU mapping

Head porting

Race Tech

Suspension revalve and setup

FMF Racing

MegaBomb stainless steel header pipe

Factory 4.1 RCT aluminum muffler

Blais Racing Services

7-ounce clutch weight

Smog delete kit for closed-course competition use

Supersprox

Front sprocket (14-tooth)

Stealth rear sprocket (51-tooth)

Enduro O-ring chain

IMS Products

3.2-gallon fuel tank

Coolant recovery tank

MotoMinded

Adjustable light mount with dimmer setup

Baja Designs

Headlight

DeCal Works

Semi-custom graphics kit

Preprinted number plate backgrounds

Graphic guards

Works Connection

Factory II stand

Front and rear brake caps

Rotating bar clamp

Steering stem nut

Clutch master cylinder cap

Scar Racing

Titanium footpegs

Dunlop Tires

AT81 front, 90/90-21

AT81 rear, 120/90-18

Uni Filter

Two-stage air filter

TM Designworks

Rear chain guide

Hinson Clutch Components

Clutch plates

Billetproof clutch cover

MotoSeat

Seat cover

Motion Pro

Titan throttle tube

Grip glue

Renthal

603 Fatbar

Grips

Bullet Proof Designs

Rear swingarm guard

Radiator guards

Rear disc and caliper guard

Tusk

Complete wheelset

Oversize front rotor

Adaptor bracket for oversize rotor

Rear rotor

Brake and sprocket hardware

Enduro Engineering

Clutch cylinder guard

Hand guards

UFO Plastic

Full plastic kit

P3 Carbon

Carbon fiber skid plate

Double Take Mirror

Enduro mirror

KTM

Orange frame guards

Two-stroke air filter cage