KH250 vs KH400 vs KH500 — Model Identifier Guide
KH250 vs KH400 vs KH500 — Model Identifier Guide
The KH series is where the Kawasaki two-stroke triple story continued after the H1 and H2. Same basic formula — inline three-cylinder two-stroke — but rationalised, refined, and in three different displacements. The KH250, KH400, and KH500 look similar at a glance. From across a field at a jumble, they look nearly identical.
Get closer and the differences are there. Frame numbers, engine case markings, tank dimensions, and the decal graphics themselves all tell you which one you're looking at. This guide is the practical reference for telling them apart.
If you're buying a donor bike, purchasing a rolling restoration, or sourcing a decal set for a bike whose documentation has been lost, this is where to start.
Why Three Displacements
Kawasaki offered the KH in three sizes to hit different market segments and licensing categories. In the UK and Europe, the 250cc class was important for learner and restricted licences. The 400cc sat in a sweet spot for unrestricted riders wanting something lighter than the 500. The 500 was the top of the range — essentially the H1 carried forward under the KH designation.
All three are triple-cylinder two-strokes. All three use the same basic engine layout. The differences are in the bore, the stroke, the carburettor size, the frame geometry, and — for decal purposes — in the graphics applied to the tank and sidecovers.
At-a-Glance Comparison
| Feature | KH250 | KH400 | KH500 |
|---|---|---|---|
| Displacement | 249cc | 399cc | 499cc |
| Bore × stroke | 45mm × 52.3mm | 57mm × 52.3mm | 60mm × 58.8mm |
| Years produced | 1976–1980 | 1976–1980 | 1976 (sole variant A8; 1977 production disputed — see Andy note) |
| Carburettors | 3 × Mikuni | 3 × Mikuni | 3 × Mikuni |
| Frame prefix | KH250B- | S3F- | H1F- |
| Engine markings | KH250 | KH400 | KH500 |
The most reliable identifier is the engine case marking. If you can read it, you know what you have. The frame number is the second check. Everything else — tank, sidecovers, exhausts — is supporting evidence.
Frame Numbers: Where to Look
The frame number is stamped into the steering head on the right-hand side. The format on KH series bikes is consistent: model prefix, then a sequential production number.
KH250: Frame prefix KH250B-, running B1 through B5 (1976–1980).
KH400: Frame prefix S3F-, carrying over from the S3 that preceded it. The frame number does not spell out "KH400" — if you're reading S3F- on the steering head of a KH-era bike, you have a KH400.
KH500: Frame prefix H1F-, carried over from the H1 500. The A8 is the sole KH500 variant. Again, the prefix does not spell out "KH500" — H1F- on a 1976 bike is the KH500 A8.
Note: KH400 and KH500 frame prefixes carry over from their predecessor models, not from the KH designation. This can confuse identification on stripped bikes — the frame prefix does not spell out "KH400" or "KH500". If in doubt, send us the number and we'll confirm the model.
The production number can be cross-referenced with registry records to establish the exact production year. If the number is partially obscured by paint or corrosion, a frame number specialist may be able to recover it. Don't try to clean a frame number with abrasives — you'll remove what's left.
Engine: Bore, Stroke, and Cases
Physically, the three engines look very similar. The KH250 is noticeably more compact — the smaller bore means a shorter case width across the three cylinders. The KH400 and KH500 are harder to separate by eye alone without a calliper.
The engine case stampings are the definitive check. On a stripped engine, look at the upper crankcase — the model designation is cast or stamped there.
Carburettor size is another indicator: the KH250 runs smaller Mikunis than the 400 and 500. If the carburettors are original and unmolested, a calliper on the carb mouth will separate the 250 from the other two. The 400 and 500 carburettors are closer in size; rely on the cases for those.
Variant Suffixes: What They Mean Across the KH Range
Within each displacement, Kawasaki used a letter-number suffix to denote the production year of a specific variant. The suffix system varies by model: the KH250 used B-series designations (B1 through B4); the KH400 used A-series (A3 through A7); the KH500 ran only the A8 variant.
KH250 B-series
The KH250 ran through B1 to B5 (1976–1980). To keep the model alive, graphic changes every model year were important — hence each year was different.
| Variant | Year | Key changes |
|---|---|---|
| KH250-B1 | 1976 | Candy Super Red or Candy Sky Blue. |
| KH250-B2 | 1977 | Candy Wine Red or Candy Orient Blue. |
| KH250-B3 | 1978 | Candy Lime Green or Candy Cobalt Blue. |
| KH250-B4 | 1979 | Candy Lime Green, Classic White, or Candy Persimmon Red. |
| KH250-B5 | 1980 | Lime Green (Kawasaki Racing). |
Note: kawatriple.com records a transitional KH250-A5 (1976) before the B-series. This variant used the S1 frame number prefix (S1E- engine, S1F- frame) and was a drum-brake model — primarily the US market configuration. The disc-brake B1 is the UK/European launch variant.
KH400 A-series
The KH400 used A-series designations throughout, continuing from the S3 that preceded it. The A-series picks up at A3 — the S3 had run through A1 and A2 before the KH rebranding. Worth knowing: the KH400 followed the KH250 graphic design, just in different colours. The two bikes were very similar — the tanks and side panels were the exact same item, just different colours.
| Variant | Year | Notes |
|---|---|---|
| KH400-A3 | 1976 | Brilliant Lime Candy (green) or Pearl Candytone Orange. |
| KH400-A4 | 1977 | Candy Emerald Green or Candy Royal Purple. |
| KH400-A5 | 1978 | Candy Persimmon Red or Candy Lime Green. Sold detuned (36bhp) in Germany and Italy. |
| KH400-A6 | 1979 | Candy Lime Green or White. Japan-only variant. |
| KH400-A7 | 1980 | Candy Lime Green. Final year. |
There is no KH400 B-series. If you encounter a source referring to KH400-B1, it is either an error or referring to the KH250 B1.
KH500 A-series
The KH500 had a shorter production run than the 250 or 400. Only one variant was produced: the A8, in 1976.
| Variant | Year | Key changes |
|---|---|---|
| KH500-A8 | 1976 | Deep Burgundy or Copper. One year model, two colours. The graphic design was the same as the KH250 B1 and KH400 A3, but the bike was altogether much larger in size — it used the same basic chassis as the last H1F 500. |
Tank: Shape and Filler Cap Position
The KH250 tank is smaller in capacity than the 400 or 500 — proportionate to the smaller engine and lighter bike. The overall tank profile is slimmer.
The KH400 and KH500 tanks are similar in profile. The mounting points and knee cutout shapes are close enough that tanks have been swapped between models on donor bikes, which complicates identification. Always rely on the frame number rather than tank shape.
Filler cap design changed across years, and can be a useful secondary identifier when tanks are swapped.
Sidecovers: The Decal Picture
The sidecover graphics are where the model designations become visually distinct. This is what you'll be reproducing in a restoration, and where accuracy matters most.
KH250 sidecovers: Carry "KH250" designation. The graphic layout, typography size, and colour treatment differ from the 400 and 500.
KH400 sidecovers: Carry "KH400" designation. Graphic layout is closely related to the KH250 — same basic panel shape — but in the KH400 colour options for each year.
KH500 sidecovers: Carry "KH500" designation. The A8 graphic shares the same family design as the KH250 B1 and KH400 A3.
Each variant can have different colour schemes while sharing the same basic graphic layout. A KH400-A3 in launch-year green looks different to a KH400-A5 in Candy Persimmon Red — same graphic, different colourway.
Exhaust: The Visual Tell from Across the Room
All three KH models run the three-into-three exhaust arrangement — one pipe per cylinder, running down each side. But the pipe diameter differs with displacement, and the exact routing and heat shield design changed across years.
Pipe diameter scales with displacement — the KH250 runs visibly slimmer downpipes than the 500. The 400 and 500 are closer; use the engine cases to confirm if in doubt.
The chrome heat shields on the downpipes changed in detail across years — earlier and later variants can be distinguished, and this can support dating when combined with the frame number.
Quick Identification by Displacement
If you have no paperwork and the stampings are unreadable, work through this checklist:
- Read the engine cases. Both sides of the upper crankcase. The model designation is there if the cases are original.
- Read the frame number. Steering head, right side. Photograph it before you try to clean it.
- Measure the carb mouths. A rough guide: smaller bore (KH250) runs noticeably smaller carbs. Don't rely on this alone.
- Look at the sidecovers. If original graphics survive — even fragmentary — the model designation text will be there. A clear photo of any remnant graphic is worth taking.
- Check the tank size. Useful as a supporting indicator, not a definitive one. Tanks get swapped.
Year-by-Year Decal Changes
For restoration accuracy, the variant suffix matters as much as the model designation. The KH250 uses a B-series (B1 through B5); the KH400 uses an A-series (A3 through A7); the KH500 ran only the A8. The sidecover graphic layout stays consistent within a model across variants, but the colour changes. A KH400-A3 in launch-year green looks different to a KH400-A5 in Candy Persimmon Red — same graphic, different colourway.
Not Sure Which You've Got?
Tell us the frame number prefix and what you can read off the engine. We'll identify the model and point you at the right decal set.
If you can photograph what remains of the original sidecover graphics — even a partial graphic — that often tells us the variant straightaway. Original colours are a strong indicator even when the text is gone.
We make decal sets for the KH250, KH400, and KH500, across the production run. Find your KH set in the catalogue →
A Note on Worn or Replaced Parts
Donor bikes at this age often have non-original tanks, sidecovers, or exhausts. Don't let a swapped component put you off a good project bike — but don't use it for identification either. The frame number and engine cases are fixed. Everything else can wander.
If the frame number and engine cases agree, you know what you have. Work outward from there.
Decals for the KH Series
We reproduce decal sets for the KH250, KH400, and KH500 — each variant, each year, correct colours and placement checked against original factory reference. We don't carry filler listings. If it's on the site, it's been done properly. A link to the fitting guide comes with every order. If you only need part of a set, get in touch and we'll see what we can do.
If your set is in the catalogue, it ships within a few days. If you're working from partial information, get in touch and we'll work it out with you. We've matched sets from a frame number prefix and a photo of a worn sidecover before. It's usually enough.
Browse the KH series collection →
— Valerie and Andy at Orchard Classic Decals
Approved Kawasaki supplier — covering Kawasaki two-stroke models: triples, KE/KT/KD/KMX, 1970s through to the last triple around 1980/81 plus a few KE models that ran into the 1990s. Reproduced from original factory reference. Not memory. Not approximation.
