2017–2027 Honda Cross-Country
Put the 450’s power to work off-road. Find parts for your model year, plan protection and fuel range, and compare the redesigned 2027 RX with the bike it replaces.
All Honda CRF Rider GuidesKnow Your RX
The CRF450RX brings Honda’s Unicam engine to cross-country competition, with an 18-inch rear wheel, sealed chain and off-road equipment. A good build starts with traction, rider fit, protection and a sound service baseline.
The RX shares its roots with the CRF450R, but a motocross parts list is not a complete off-road setup. Match the rear wheel, tank, controls and engine calibration to the RX. The CRF450X and CRF450L/RL are different platforms with their own parts applications.
A part listed through 2026 is not automatically confirmed for the 2027 CRF450RX. Check the new application for exhausts, ECUs, intake and engine parts, tanks, seats, plastics and frame-mounted protection.
Start Here
Identify the RX by model year, then note any changes to the wheels, fuel tank, engine, exhaust or suspension.
Find Your GenerationCheck intake sealing, fluids, engine history, bearings and the drivetrain before adding performance parts.
Review RX MaintenanceSet sag and controls, choose tires for the terrain and measure fuel use before planning longer loops.
Choose Your UpgradesModel-Year Roadmap
The RX begins with the 2017 model year. These groups help narrow the search; individual products can fit shorter or overlapping year ranges. On a phone, swipe across the table.
| Model years | Platform reference | Buying priority |
|---|---|---|
| 2017–2018 | First RX models / dual exhaust | Confirm the early RX tank, seat, controls and exhaust application. Check installed equipment on a used bike. |
| 2019–2020 | Later dual-exhaust applications | Some engine, exhaust and electronic products split from 2017–2018. Match the exact year even when the bodywork looks familiar. |
| 2021–2022 | Single exhaust / hydraulic clutch | Choose levers and clutch parts for hydraulic actuation and exhaust parts for the single-muffler layout. |
| 2023–2024 | Later engine and intake applications | Check engine, exhaust and electronics listings carefully; use the product’s own year range. |
| 2025–2026 | Latest pre-2027 applications | Match chassis, intake, suspension and protection parts to these years. Do not extend them automatically to 2027. |
| 2027 | New engine, frame and associated components | Start a new parts list. Verify a specific 2027 CRF450RX application and use the revised stock specs and service schedule. |
Use the full model designation and model year, rather than graphics or the purchase date. A shared R/RX product must include your RX year.
New for 2027
Honda redesigned the engine and chassis for 2027. The changes affect both the parts you order and the service references you keep in the garage.
Listed for the New Bike
These products have explicit 2027 R/RX applications. Check the available options and current release or backorder terms on each product page.
The titanium RS-12 EVO full system is listed for the redesigned 2027 CRF450RX and uses a new hydroformed muffler and carbon end cap.
Acerbis’ original-color plastic kit replaces the principal body panels using the factory shapes for the new model.
A pre-drilled red Acerbis front fender replaces a damaged original when only the front fender is needed. The full plastic kit above already includes one.
Tell us your riding goals and the parts you want to use. We can help check the application before you order.
Stock Specs by Model Year
These figures apply to the U.S. CRF450RX in the stated year. Use the exact-year manual for an older or modified bike. On a phone, swipe across the table to compare.
| Specification | 2026 CRF450RX | 2027 CRF450RX |
|---|---|---|
| Front tire | 90/90-21 / Dunlop AT81 | 90/90-21 / Dunlop AT81 |
| Rear tire | 120/90-18 / Dunlop AT81 | 120/90-18 / Dunlop AT81 |
| Rear wheel | 18-inch | 18-inch |
| Front sprocket | 13 tooth | 13 tooth |
| Rear sprocket | 50 tooth | 51 tooth |
| Stock drive chain | Sealed #520 / 114 links | Sealed #520 / 116 links |
| Spark plug | NGK SILMAR9A-9S | NGK SILMAR9A-9S |
| Spark-plug gap | 0.80–0.90mm / non-adjustable | 0.80–0.90mm / non-adjustable |
| Engine | 450-class Unicam SOHC four-stroke | Redesigned 450-class Unicam SOHC four-stroke |
| Fuel injection | PGM-FI / 44mm throttle body | PGM-FI / 46mm throttle body |
| Starting | Electric | Electric |
| Transmission | Close-ratio five-speed manual | Close-ratio five-speed manual |
| Clutch actuation | Hydraulic | Hydraulic / new clutch assembly |
| Fuel capacity | 8.0L / 2.11 US gal / resin tank | 7.1L / 1.88 US gal / titanium tank |
| Fuel specification | Unleaded; minimum 91 pump octane | Unleaded; minimum 91 pump octane |
| Oil after draining | 1.00L / 1.06 US qt | 1.07L / 1.13 US qt |
| Oil with filter change | 1.04L / 1.10 US qt | 1.10L / 1.16 US qt |
| Oil specification | SAE 10W-30 / JASO MA / API SJ or higher | SAE 10W-30 / JASO MA / API SJ or higher |
| Seat height | 37.7 inches | 37.4 inches |
| Brake discs, front / rear | 260mm / 240mm | 260mm / 240mm |
Check the RX specifications and procedures in Honda’s 2026 owner’s manual or 2027 owner’s manual. Engine and transmission share an oil supply; follow the correct fill and level-check procedure and exclude oils marked “Energy Conserving” or “Resource Conserving.” Chain length depends on the installed gearing and axle position. A replacement chain may be supplied longer than the stock installed length.
View Honda’s 2027 RX specificationsChoose Your Goal
The selections below cover 2017–2026 applications. Each card shows its own fitment or ordering requirements. Use the dedicated 2027 section for the new platform; product pages provide current prices and availability.
Protection & controls
Start with the parts exposed to rocks, roots and tip-overs. These selections cover earlier RX models through 2026; the redesigned 2027 bike needs its own application check.
An 8mm HDPE plate adds coverage around the frame, suspension linkage, engine cases and water pump for rocky off-road riding.
Billet aluminum guards add protection against front and side impacts around the radiators while retaining airflow openings.
Wraparound aluminum bars and shields help protect your hands and controls when riding through brush or tipping over.
An adjustable short brake lever lets you set the reach and can fold outward in a fall to help reduce lever damage.
Suspension & comfort
Record your sag and damping settings before changing parts. Spring rate, lowering and seat shape solve different problems, so choose the change that addresses how the bike fits and handles for you.
A different fork spring rate changes front-end support when the installed springs do not suit your riding weight or pace.
K-Tech’s replacement compression adjuster adds a way to refine shock compression settings for off-road terrain and the installed linkage.
Kouba’s replacement linkage offers approximately 1.5 or 2 inches of rear lowering for riders who need an easier reach to the ground.
The standard comfort profile widens the seating area to 7.5 inches for more support during longer seated stretches.
Power delivery & range
Choose fuel and ignition settings around the actual model year and engine configuration. A clutch change can refine engagement, while a larger RX-specific tank addresses a different need: carrying enough fuel for the route.
The Vortex X10 provides 10 fuel and ignition maps plus low-, mid- and high-throttle fuel trims for a competition setup matched to your engine and exhaust.
The Rekluse Apex replaces the hub, pressure plate and clutch pack to refine manual clutch modulation with a choice of spring combinations.
Acerbis’ 3.1-gallon tank adds fuel capacity for rides or races with longer gaps between refueling stops.
The IMS 3.0-gallon tank adds capacity to the first-generation RX for longer stretches between fuel stops.
Exhaust & intake
Exhaust shape, mounting and intake parts change across RX generations. Check sound and spark-arrestor requirements separately before choosing a race or trail setup.
The RS-12 stainless full system combines a hydroformed header and muffler with a resonator for the 2025–2026 exhaust layout.
The FMF Factory 4.1 slip-on replaces the muffler with a stainless system using a carbon end cap and application-tuned core.
A spare dual-stage foam filter makes it easier to prepare a clean filter before a dusty ride or race.
This replacement end cap adds a removable U.S.F.S.-approved spark-arrestor screen to the matching stock muffler.
Drivetrain
Inspect the drive chain, both sprockets, chain guide and axle adjustment together. Start with your stock gearing and record each change so its effect is easy to assess.
A narrow X-ring chain retains lubrication at its joints while providing a replacement option for a worn 520 drive chain.
A nickel-chromoly front sprocket replaces worn teeth or lets you change final gearing by selecting a different tooth count.
A protective guide body and replaceable wear pad help keep the chain guided through rough off-road terrain.
The TwinRing combines an aluminum center with a steel tooth ring for riders balancing sprocket weight and wear life.
Maintenance & engine service
Use Honda’s schedule for your RX year and follow the engine’s actual fill and level-check procedure. Service parts should match the engine and suspension installed on the motorcycle.
This kit gathers two liters of Maxima Pro Plus 10W-40, a K&N oil filter and the filter-cover and drain O-rings for an oil service.
An SKF oil seal and dust seal replace worn sealing parts when servicing a leaking fork leg.
The NGK SILMAR9A9S is a replacement plug option for the earlier RX engine application covered by this listing.
CRF’s Only reconditions your cylinder head with inspection, performance porting, valve-seat work and replacement race-series seats and guides.
Build Your Setup
Choose the starting point that matches your motorcycle and the way you ride.
Build 01
Build 02
Build 03
Build 04
Keep It Ready for the Next Race
Record riding hours, race count and service dates. Honda’s RX competition schedule uses different race counts from the R, and the 2027 engine introduces changes of its own.
| Service item | 2026 RX | 2027 RX |
|---|---|---|
| Before every ride | Inspect fluids, filter seal, throttle, brakes, clutch, tires, chain, spokes, leaks and fasteners. | Same pre-ride priorities; use the 2027 checklist. |
| Air filter | Clean each race / about 3.5 hours; more often in dust. | Clean each race / about 3.5 hours; more often in dust. |
| Spark-plug inspection | Each race / about 3.5 hours. | Every 4 races / about 15 hours. |
| Sealed drive chain | Inspect before riding; clean and lubricate after every ride. Scheduled replacement: 2 races / about 7.5 hours. | Same care and replacement timing; stock installed length changes to 116 links. |
| Swingarm / shock linkage | Lubricate every 2 races / about 7.5 hours. | Lubricate every 2 races / about 7.5 hours. |
| Engine oil and filter | Replace every 4 races / about 15 hours. | Replace every 4 races / about 15 hours; use the revised fill quantity. |
| Valves / decompressor | Inspect every 4 races / about 15 hours. | Inspect every 4 races / about 15 hours; follow the new engine specifications. |
| Piston, rings and piston pin | Replace every 4 races / about 15 hours. | Replace every 8 races / about 30 hours. |
| Clutch-center dampers | Follow the 2026 clutch inspection procedure. | Replace every 4 races / about 15 hours. |
| Crankshaft / seal plate | Follow the 2026 engine inspection procedure. | Inspect every 8 races / about 30 hours. |
| Fork oil / steering bearings | Replace fork oil and inspect steering bearings every 6 races / about 22.5 hours. | Same interval; use 2027 suspension procedures and settings. |
| Fuel line / fuel-pump filter | Replace every 8 races / about 30 hours; annual replacement also specified. | Replace every 8 races / about 30 hours; annual replacement also specified. |
| Break-in and periodic fluids | After the first break-in ride: replace oil/filter/fork oil and inspect valves. Replace coolant, brake fluid and clutch fluid every 2 years. | Same break-in and 2-year fluid work, plus the specified break-in idle-speed inspection. |
| Severe use or uncertain history | Inspect and service sooner after heavy dust, water exposure or signs of wear. | Inspect and service sooner after heavy dust, water exposure or signs of wear. |
These are selected items from Honda’s RX competition schedule, using the manufacturer’s race counts and approximate hours. Follow the complete 2026 Competition Handbook or 2027 Competition Handbook, including break-in and recurring inspections. The new piston interval does not establish a guaranteed service life or reduce other maintenance. Use an exact-year manual for 2017–2025 bikes.
Common Questions
Stock sizes, fuel range, model differences, 2027 fitment and service planning.
No. Honda redesigned the engine and chassis for 2027. Changes include a new intake and clutch assembly, revised gearing, different chain length, a titanium fuel tank and updated service references. Treat it as a separate parts application.
Some items may share dimensions or a specification, but that is not enough to confirm the application. Check each part for an explicit 2027 RX listing, especially exhausts, ECUs, air filters, engine parts, tanks, seats, plastics and protection. Contact us before ordering if the listing stops at 2026.
The RX is the cross-country version with an 18-inch rear wheel, off-road suspension setup, sealed chain and off-road equipment. The R uses a 19-inch rear wheel. Tank and gearing differences depend on year: the 2027 RX’s titanium tank is not the previous 8.0L resin tank. Always select the full model name.
No. The RX is a cross-country competition platform with a close-ratio five-speed gearbox. The current X and L/RL use different platforms and six-speed transmissions. Choose their own product applications; a shared 450 designation does not confirm fitment.
The U.S. 2026 and 2027 CRF450RX use 90/90-21 front and 120/90-18 rear tires, with Dunlop AT81 as the stock reference. Match tires, tubes and inserts to the wheels actually installed on the bike.
The 2026 RX uses 13 teeth front / 50 rear. The 2027 RX uses 13 front / 51 rear. More rear teeth or fewer front teeth shorten the final gearing. Recheck chain length, guide clearance and axle adjustment when changing tooth counts.
Both current references use a sealed #520 chain. Stock installed length is 114 links for 2026 and 116 links for 2027. A supplied 120-link replacement needs correct sizing; do not confuse package length with installed length. Follow the chain manufacturer’s connecting-link procedure.
Honda specifies NGK SILMAR9A-9S for the U.S. 2026 and 2027 CRF450RX, with a non-adjustable 0.80–0.90mm gap. Check the exact-year manual for an older RX. Matching the current plug code does not establish compatibility for other engine parts.
The 2026 RX takes 1.04L / 1.10 US qt; the 2027 RX takes 1.10L / 1.16 US qt. Both current manuals specify SAE 10W-30, JASO MA and API SJ or higher, excluding energy/resource-conserving oils. Follow the exact-year level-check procedure.
The 2026 and 2027 RX engine and transmission share lubrication. Do not use a separate-transmission oil quantity from an older or different CRF model. Check your model year’s manual for filling and level checks.
Do not assume it does. Tank capacity changes from 8.0L in 2026 to 7.1L in 2027, and consumption depends on terrain, pace and setup. Measure fuel use on representative rides and keep a reserve. An older oversized tank also needs new-year fitment confirmation.
Yes. The RX uses electronic fuel injection and electric starting. Carburetor jet kits are not an RX tuning solution. Check battery condition and EFI fault information when diagnosing hard starting.
The 2021-and-later RX uses hydraulic clutch actuation; the early 2017–2020 models use a cable. The 2027 bike retains hydraulic actuation with a redesigned clutch assembly. Match lever and clutch parts to your year.
Start with engine health, sag, controls and tires. Evaluate the factory engine modes available on your year before deciding what response you want to change. Then plan the exhaust, intake and calibration together around your actual engine configuration.
Requirements depend on the riding area and event. Check the exact muffler and screen fitted to the bike. A spark-arrestor screen and a sound limit are separate requirements; verify both when choosing an exhaust.
Use the RX table in the matching Honda handbook. RX oil/filter service is every 4 races / about 15 hours in the current reference, rather than the R’s race count. The 2027 RX also changes piston, plug and clutch-damper service items.
Confirm the model year and RX identity, request a cold start and review engine-service records. Inspect intake sealing, radiator and case damage, bearings, fork seals, chain guides and the installed tank/exhaust/ECU combination. An hour meter alone does not establish total engine time.
Build Your CRF450RX
Find CRF450RX parts, plan a longer-range setup or get help checking applications for the new 2027 bike.
