By Jay Clark

The goal of this project was to simply pin it. Jay Clark wanted to build the best two dual sports possible for himself and his son. Since they are the most popular bikes in the category, why not start with two KTM 500 EXC-Fs? Because what is the fun in that?  The 350 EXC-F is lighter and nimbler, and Cylinder Works has a Big Bore kit for it that makes it a 366cc, but that difference, combined with the other mods, gives you a race bike feel on a dual sport bike. 

We had two bikes for this project: a 2019 and a 2017. Race Tech did the 2017 motor and made over 50 horsepower! Twisted Development did the work on the 2019 model and their numbers were the same. The stock units are very corked-up with only 34 horsepower stock, which is fine for just cruising. We wanted to get a little more aggressive and make a race bike feel on a street legal dual sport bike. 

Aside from the motor modifications, there were a few parts to making these bikes great. Weight was added to the clutch for more tractable power and less flame out incidents. Blais Racing made those weight kits and they are worth every penny. Also, the blinkers were a custom setup and tucked in with blinker relays. SAR made these and these are must-haves. SAR makes a number of custom plug and play items for the KTM EXC-F’s, and these make a big difference for the guy modifying his EXC-F. After a few trips on the trail you learn 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. The switches for the lights and blinkers allow you run the clutch perch where you would like since it is slimmer and the same goes for the front brake side with the starter/kill switch.   

We tested these on the mean streets and dirt of Perris, California. We cruised from Perris MX up through the city of Perris until we hit a dirt road. From there we chased trails until we found ourselves on top of a mountain looking down on the track. The power on these 350s felt like 500s. In fact, they may even be a little better. The throttle response is like a motocross bike and the power felt like a 350 SX-F, not an EXC-F. The power was most fun once we got into the dirt, as trails and obstacles we so easily negotiated. The power is sharp and strong, allowing you to power your way through anything. I’d put these up against a 500 EXC-F any day.

SAR

SAR Easy Fit Under Fender LED Tail Light and License Plate Mounting Plate, Clear Lens 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 (Allows you to take off the OE key switch), Over/Under Start/Stop Switch (Kill button does not lock down), SAR Keyed Kill Switch (A key switch that doesn’t kill the battery!), Multi-function Light Control Switch (OFF – LOW – HIGH)
www.sicassracing.com 

Cylinder Works

2mm Big Bore Cylinder Kit 366cc, Includes Forged Vertex Piston and Top-End Gasket Kit
www.cylinder-works.com

Twisted Development    

Vortex X-10 ECU & Mapping, Head Porting to Match the Big Bore Cylinder (2019 #101)
www.td-racing.com

Race Tech

Suspension Re-Valve and Setup on Both Bikes, Head Porting to Match the Big Bore Cylinder (2017 #133)
www.racetech.com

FMF Racing

SS Header, Alum F 4.1 RCT Muffler
www.fmfracing.com

Blais Racing Services 

Clutch Weight, Smog Delete for Closed Course Competition Use  
www.blaisracingservices.com

Supersprox

Front 14T, Rear 51T Gold Stealth Sprocket, Gold Enduro O-Ring Chain  
www.supersproxusa.com

IMS           

Large Tank, Coolant Catch Can
www.imsproducts.com 

MotoMinded

Adjustable Light Mount with Dimmer Set Up (2019 #101)
www.motominded.com

Baja Designs  

Head Lights 
www.bajadesigns.com

DeCal Works 

Semi-Custom Graphics Kit with Toxic Yellow, Pre-printed Number Plate Backgrounds
www.decalmx.com

Works Connection

Factory II  Stand, Front & Rears Brake Caps, Clutch Master Cylinder Cap, Rotating Bar Clamp, Steering Stem Nut
www.worksconnection.com 

Scar

Titanium Footpegs
www.scar-racing.com 

Dunlop

AT81 Front (90/90-21), AT81 Rear (120/90-18)
www.dunlopmotorcycletires.com

Uni Filter

Two Stage Air Filter
www.unifilter.com

TM Designworks

Rear Chain Guide 
www.tmdesignworks.com

Hinson Clutch Components

Clutch Plates and Outer Cover
www.hinsonracing.com 

MotoSeat

Custom Cool Seat Cover
www.motoseat.com

Motion Pro

Titan Throttle Tube, Grip Glue
www.motionpro.com

Renthal

603 Fat Bars, Grips
www.renthal.com

Bullet Proof designs

Rear Swingarm Guard, Radiator Guards, Rear Disc and Caliper Guard 
www.bulletproofdesigns.com 

Tusk

Oversized Rotor/Adaptor Bracket, Complete Wheelset, Oversized Rotor Front, Rotor Rear, Brake and Sprocket Hardware
www.tuskoffroad.com 

Enduro Engineering 

Clutch Cylinder Guard, Hand Guards
www.enduroeng.com

UFO Plastic

Full Plastic Kit Orange (2019 #101), Full Plastic Kit Flo Orange (2017 #133)
www.ufoplasticusa.com 

P3 Carbon

Carbon Skid Plate 
www.p3carbon.com 

Double Take Mirrors 

Folding 4” Rear View Mirrors
www.doubletakemirror.com

KTM Parts

Frame Guards, Two-Stroke Air Filter Cage 
www.ktm.com/us/ktmpowerpartsus/

ABOUT PRO CIRCUIT

Based in Corona, California, Pro Circuit Products, Inc. is a leader in off-road motorcycle and ATV exhausts and aftermarket performance parts. Started in 1978, Pro Circuit is the go-to shop for recreational riders and professionals for everything from suspension work to complete engine packages, and everything in between.

ABOUT NAMURA TECHNOLOGIES

Pistons and Gaskets Coming from decades of Powersports aftermarket manufacturing, Namura continues to impress riders and dealers alike with their aggressive development and innovative product design and manufacturing in MX and ATV Pistons and Gaskets. Based out of the suburbs of Minneapolis, Minnesota, Namura is taking piston quality and durability to another level.