Target Audience:
Motocross racers, cross-country competitors, and serious DIY owners
Segment:
Competition off-road four-stroke motocross
Key Advantage:
High-output single-cylinder RFS engine with electric and kick start
Versus Competition:
Lightweight chassis and easy four-stroke torque compared to Honda CRF450R and Yamaha YZ426F
Engine:
510cc liquid-cooled single with four-valve DOHC head
Suspension:
WP upside-down fork and WP rear shock
Starting:
Electric start with backup kick starter
Engine:
Complete teardown, inspection, and rebuild of the RFS single
Cylinder Head:
Valve clearance adjustment, valve job, camshaft timing, head torque sequence
Fuel System:
Keihin FCR carburetor disassembly, jetting, float height, and tuning
Lubrication:
Oil pump, pressure relief, oil lines, and lubrication circuits
Cooling System:
Radiator, water pump, thermostat, and coolant specifications
Ignition and Electrical:
CDI ignition, stator, spark plug, starter circuit, and wiring diagrams
Clutch:
Wet multi-plate clutch removal, plate inspection, and adjustment
Transmission:
Gearbox disassembly, shift drum, fork wear limits, and reassembly
Final Drive:
Chain adjustment, sprocket wear limits, and countershaft service
Frame:
Frame inspection and steering head bearing service
Front Suspension:
WP fork disassembly, seal replacement, oil volume, and spring rates
Rear Suspension:
WP shock removal, linkage service, sag setting, and spring preload
Wheels and Brakes:
Wheel truing, spoke torque, brake pad and disc service, master cylinder bleeding
Body and Controls:
Plastics, seat, levers, throttle, and control cables
Procedures:
Step-by-step disassembly, assembly, inspection, and troubleshooting procedures
Specifications:
Torque specs, wear limits, clearances, and fluid capacities throughout
Tools:
Lists of required special tools for each job
Diagrams:
Exploded views, wiring diagrams, and service illustrations
Part Numbers:
Factory part references included for service components
Consumables:
Specified oils, coolants, sealers, and fastener data
File Format:
PDF (searchable, bookmarked, zoomable)
Compatibility:
Windows, macOS, Linux, iOS, and Android — any device with a PDF reader
Requirements:
A PDF reader application (e.g. Adobe Acrobat Reader, free)
Searchability:
Fully text searchable for fast lookup of any topic
Print Quality:
High-resolution digital pages, printable at full clarity
Binding Type:
N/A — digital download, no physical binding
Paper Type:
N/A — digital download, no physical paper
Primary Engine:
510cc liquid-cooled single-cylinder four-stroke
Engine Family:
KTM RFS (Racing Four-Stroke)
Valvetrain:
DOHC, four valves per cylinder
Bore and Stroke:
95mm x 72mm
Starting:
Electric and kick start
Carburetor:
Keihin FCR flatslide carburetor
Fuel:
Premium unleaded gasoline
Wheelbase:
Approximately 58.1 in (1475 mm)
Length:
Approximately 85 in (2160 mm)
Seat Height:
Approximately 37.4 in (950 mm)
Ground Clearance:
Approximately 14.6 in (370 mm)
Fuel Capacity:
Approximately 2.0 gal (7.5 L)
Curb Weight:
Approximately 247 lb (112 kg)
Engine Oil:
Change after every race day or approximately every 10 hours of operation
Valve Clearance:
Check every 15-20 hours of operation
Air Filter:
Clean and re-oil after every ride in dusty conditions
Piston and Rings:
Inspect every 40 hours; replace on a regular race schedule
Coolant:
Replace annually
Chain and Sprockets:
Inspect and adjust before every ride
Engine Oil:
High-quality motorcycle 4-stroke oil meeting API SF/SG or higher
Coolant:
Mixed with corrosion inhibitor per manual ratio
Fork Oil:
WP-spec suspension fluid per chassis settings chart
Known Issues and Wear Items
Valve Wear:
Intake valve and seat wear common on high-revving RFS engines; frequent clearance checks required
Cam Chain Tensioner:
Manual tensioner inspection recommended
Water Pump Seals:
Monitor coolant level; seals are a common wear item
Clutch Plates:
Friction plates wear quickly under race use
Manufacturer:
KTM, founded 1934 in Mattighofen, Austria
Racing Pedigree:
Multiple Enduro and Motocross World Championships in the four-stroke era
RFS Platform:
Introduced in 2000 with the 400/520 four-stroke single-cylinder family
Evolution:
Refined through 2007 with updated suspension, carburetion, and chassis tuning
Successor:
Replaced by the 505 SX-F four-valve platform in 2007
Production Location:
Mattighofen, Austria
