Model-year news is usually a graphics update and a press release. Not this time. For 2027, Honda has rebuilt the CRF450R engine from the crankcases out, Kawasaki has launched its first two-stroke bigger than 250cc in over two decades, and Yamaha has given the YZ250F an all-new motor. KTM, which spent the last few years doing the heavy lifting, is the one standing still.
Here is what actually changed, brand by brand, and the one rule quietly shaping all of it.
Honda 2027 CRF450R: the most serious update in a decade #
Honda calls this the most comprehensive CRF450R revision in over ten years, developed with HRC input, and the spec sheet backs it up. The engine is new rather than revised: bore grows 1mm to 97.0mm against a 60.8mm stroke, and compression rises from 13.5:1 to 13.8:1.
Internally, the crankshaft moves to a round profile and runs roller-only journal bearings. Intake valves grow 2mm to 40mm, exhaust valves 1mm to 32mm and switch to titanium, and the top compression ring gets a DLC coating. The result is an engine roughly 6 lb lighter and 17mm narrower than the one it replaces.
Weight is the headline. Across the whole bike Honda claims a saving of over nine pounds — around 4kg — which is a lot to find on a machine that was already competitive. About 70% of the main frame components are new, and Honda says frame rigidity is up roughly 10% with no weight penalty, which is the hard part of that trade.
Suspension and intake get matching attention: the fork spring rate goes from 5.0 to 5.2 N/mm, the shock switches to SS37 oil, and the airbox flows with about 10% less resistance. Three ride modes and three levels of Honda Selectable Torque Control carry over as the tuning interface.
Kawasaki KX327: a 327cc two-stroke, from a factory, in 2027 #
This is the news of the year. Kawasaki has introduced the KX327 and KX327X — a 327cc liquid-cooled two-stroke with fuel injection and electric start. It is the brand’s first production two-stroke over 250cc in more than twenty years, and it arrives with a chassis derived from the KX450F rather than something built down to a price.
Claimed weight is around 233.7 lb (about 106kg). The split between the two versions is the usual motocross-versus-off-road divide: the KX327 runs a 19-inch rear wheel and a five-speed gearbox, while the KX327X gets a 21/18-inch wheel pairing, a six-speed box, a larger tank, handguards and a skid plate. US MSRP is $9,099 and $9,699 respectively, with availability late in 2026 — European pricing will differ, so treat those as reference points rather than what you will pay.
A fuel-injected big-bore two-stroke changes the ownership maths in ways worth thinking about before you get excited. Injection takes carburettor guesswork off the table, but premix, piston intervals and gearing choices are all still yours to manage. If you are weighing the switch on principle rather than on spec, our breakdown of two-stroke versus four-stroke ownership covers the parts that do not show up in a press release, and the premix ratio chart and jetting calculator are there for the bikes that still need them.
The four-strokes were not left alone either. The 2027 KX450F gets a redesigned aluminium perimeter frame, a revised swingarm and a longer wheelbase, new intake and exhaust hardware with matching fuel-injection settings, Brembo brakes front and rear, reworked launch control, and Bluetooth connectivity with a GPS trip log through Kawasaki’s app. The KX250F is a smaller step: a more hemispherical combustion chamber worth roughly 0.7 hp, an exhaust header 3.5 inches longer, 15% more clutch spring load, revised suspension settings, a slimmer number plate and a front fender shortened by 1.2 inches. US pricing runs $10,299 for the KX450F and $8,599 for the KX250F.
Yamaha 2027 YZ250F: new engine, higher ceiling #
Yamaha’s 250F gets an all-new engine with the rev limit raised by 700 rpm, using finger-follower rocker arms derived from the YZF-R1 superbike plus intake changes that let it breathe at those revs. Finger followers have become standard practice for high-rpm 250Fs, and this is Yamaha’s turn.
The five-speed gearbox moves to a tri-shaft layout that stacks the shafts vertically for a lighter, more compact package. The clutch is new as well: a disc spring replaces the coil springs, and the primary gear and basket are combined into a single steel unit, which Yamaha says gives lighter lever effort and smoother engagement. On a 250F, where the clutch does most of the work of keeping the engine in its range, that is the change riders will feel first.
Traction and launch control settings are revised and still tuned through the Power Tuner app, and there is a new ECU lock as a theft deterrent. US MSRP is $9,099, or $9,299 for the Monster Energy edition, arriving September 2026.
KTM 2027: graphics, and a quieter engine #
After several years of substantial revisions, KTM is consolidating. The 2027 SX line runs to nine models with a new colourway, unchanged WP XACT suspension and the same frame. The mechanical work that is there went into engine updates to meet the latest FIM and AMA sound regulations — including on the two-strokes.
The one range change matters if you were shopping the small bikes: there is no 150 SX for 2027. KTM has historically introduced Factory Edition models later in a season, so the picture may not be final, but as things stand this is a holding year for the Austrian brand while Japan moves.
The rule behind the engineering: sound limits #
Sound is the thread running through more of this than the marketing admits. From 1 January 2025 the FIM cut its motocross limit by 3 dB, from 114 dB to 111 dB. That 111 dB is really a 109 dB target with a 2 dB allowance for the precision of the measuring equipment, and further reductions have been signalled. Three decibels is a large cut when you are already designing to the limit.
That is a racing rule, but it drives production hardware, because manufacturers homologate and market bikes against the series their customers watch. Yamaha is the most explicit about it: it states that the YZ250F’s revised airbox and tuned exhaust are there to meet FIM and AMA noise regulations while the engine makes more power — which is the harder version of the problem, since power and quiet usually pull in opposite directions.
It is also a survival issue at club level: tracks close over noise complaints from neighbours far more often than they close over anything else. When KTM says it updated its engines for the latest sound rules and Kawasaki fits a longer exhaust header, that is the same pressure showing up in different engineering departments.
What it means if you are buying #
If you ride a 450, the 2027 CRF450R is the bike to go and sit on. A claimed 4kg saving plus a stiffer frame is the kind of change you feel in the second half of a moto, not just on paper. If you have been waiting for a factory-built big-bore two-stroke, Kawasaki has ended the wait — but it is a first-year model, and first-year models are worth a season of other people’s ownership reports before you commit.
If you are on a 250F, Yamaha’s is the one to watch — a genuinely new engine rather than a revision, and the class has not seen many of those lately. And if you were set on a KTM, this is a good year to buy a leftover 2026 at a discount rather than pay new-model money for fresh graphics.
Worth remembering that model-year gains are usually smaller than setup gains. A bike that is 4kg lighter is a real improvement; a bike with the sag set correctly and the right tyre pressure is often a bigger one. If you want the previous year’s field for context, our 2026 motocross bike comparison lays out where each brand stood before this reshuffle.
Sources #
- Racer X — Redesigned CRF450R Headlines Honda’s 2027 Off-Road Motocross Range
- Racer X — Kawasaki Introduces 2027 Off-Road Lineup: KX250F, KX450F and KX327 Two-Stroke
- Dirt Bike Magazine — First Look: 2027 Kawasaki KX450F and KX250F Revealed
- Motorcycle.com — 2027 Kawasaki KX327 and KX327X First Look
- Racer X — Yamaha Introduces All-New 2027 YZ250F
- Racer X — What Changes Do the 2027 KTM Motocross Bikes Have?
- FIM — Sound Regulations 2026 (PDF)
- MXMag — New Noise Standards in MXGP
