Series 390 — Precision Reborn · Build Archive
A documented frame-off catalog of 1969–1975 Kawasaki 500cc two-stroke triples — every machine rebuilt to specimen grade, every machine stamped.
Catalog Index · 40+ delivered builds
Frame-Off Restorations, Filed by Variant & Year
Filter the archive below to follow the platform’s evolution from the 1969 H1 to the final 1975 S2 production run. Each plate is a notarized record of a completed machine.
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390 Stamp № 0011971 H1 500
Retained by the Barber Vintage Motorsports Museum — reference collection.
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390 Stamp № 0121972 H1R 500
Numbers-matching works-replica · shipped to a Belgian privateer collection.
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390 Stamp № 0281974 H1F 500
Crate-and-ship delivery to Osaka · on-time across customs, 2024.
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390 Stamp № 0431975 S2 500
Final-year production, returned to factory-correct livery · repeat client build.
Indexes above are excerpted. The full dossier archive — 200-hour dyno reports, leak-down charts, before/after plates, and provenance trail — is available to qualified collectors on request.
Read the Build ProcessPlatform Coverage
Every Variant, Repeatedly Rebuilt
The 1969–1975 Kawasaki 500cc two-stroke triple is six distinct platforms, each with its own parts ecosystem, dyno signature, and collector audience. Below is the documented rebuild count per variant on file at Studio 7B.
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01
H1 — The Original Triple
1969–1971 · 500cc
- Rebuilt to date
- 11
- Avg. cycle
- 11.5 months
The platform that started the catalog. Our H1 builds emphasize originality: NOS tank graphics sourced from the Akashi archives.
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02
H1R — Works Replica
1971–1972 · 500cc
- Rebuilt to date
- 6
- Avg. cycle
- 14 months
Homologation specials. Each rebuild includes the factory race-kit intake manifold and period-correct Mikuni VM carbs.
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03
H1F — Refined Roadster
1973–1975 · 500cc
- Rebuilt to date
- 9
- Avg. cycle
- 10.5 months
Five-port cylinder head, CDI ignition. Strongest repeat-client platform in the archive — six of nine builds returned for second restorations.
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04
H2 — The Widowmaker, Tamed
1972–1975 · 750cc
- Rebuilt to date
- 8
- Avg. cycle
- 12 months
750cc expansion-chamber triples. Our dossier package includes a 200-hour dyno sweep — required reading before any H2 is returned to a private garage.
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05
S1 — The Street Triple
1971–1975 · 500cc
- Rebuilt to date
- 7
- Avg. cycle
- 10 months
Lower compression, civilised cam timing. The most-ridden platform in the archive — three builds currently on active vintage-race circuits.
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06
S2 — Final-Year 500
1972–1975 · 500cc
- Rebuilt to date
- 5
- Avg. cycle
- 10 months
The last 500cc triple off the Akashi line. Scarcity drives a 14-month queue at current intake.
The dossier is not paperwork. It is the machine’s permanent record — the dyno sweep that proves what the engine is, the leak-down chart that proves what it will be, and the notarized stamp that proves who built it. Once a Kent He 390 leaves the studio, it cannot be confused with anyone else’s work, and it cannot be quietly lost.
Every build, every time
The Standard 390 Dossier — Five Items, No Substitutions
What ships in the crate alongside every frame-off rebuild. The same five deliverables have left Studio 7B on every delivered build since 2018.
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01
200hr
Dyno Sweep Report
A bound, signed run-sheet logging every dyno session across the full 200-hour break-in — signed by the lead technician.
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02
96pp
Bound Dossier
Before/after photo plates, parts sourcing log, build sheet, dyno graphs, leak-down chart, and the studio’s archive correspondence on the chassis number.
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03
1ea
390 Stamp & Frame Tab
A numbered frame-tab welded to the steering head, plus the matching collector card — the machine’s permanent signature on the platform.
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04
3psi
Leak-Down Compression Chart
Per-cylinder cold & hot leak-down expressed to ±0.5psi, recorded at three intervals across the break-in cycle. A collector’s mechanical fingerprint.
A 390 build is the only Kawasaki triple restoration shipped with this standard of record.
Read About the 390 StampCollector Logistics
Questions Serious Collectors Ask First
Practical answers to the operational questions that come up before a deposit is wired. Nothing here is aspirational — these are the answers we give by phone every week.
- Do you ship internationally?
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Yes. Crate-and-ship deliveries have been completed to 11 countries on four continents. We build an ISPM-15 heat-treated wooden crate in-house, contract with a specialist two-wheeler freight forwarder, and handle customs paperwork, ATA Carnet filing, and destination-side white-glove placement.
- How does the 390 Stamp and notarized provenance transfer with the sale?
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The 390 Stamp is welded to the steering head and travels with the chassis permanently. The notarized provenance certificate is signed over to the new owner at the point of sale and counter-filed with the Hagerty specialist-referral network record — so the build’s history follows the machine for the rest of its service life.
- What is the typical build cycle, and is it a guaranteed delivery window?
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Our average rebuild cycle is 11 months — 38% faster than the next-fastest independent marque specialist. We provide a written estimate at intake, not a guaranteed window, because parts sourcing for a 1969–1975 Kawasaki triple can introduce real-world delays we will not promise around. The last 24 builds were delivered on or before estimate at a 92% rate.
- Do you accept consignments or only direct purchase?
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Both. Direct purchases are most common — clients bring us a barn-find or a tired runner and we restore it back to them. Consignments are accepted case-by-case for documented, numbers-matching machines where the consignor wants the 390 dossier on file at sale; terms are negotiated per build.
- Is the build insured while it is in the studio?
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Yes. Aggregate insured build value on file across active restorations currently sits above $4.2M since founding. The studio carries a specialist classic-motorcycle policy through Hagerty, and every client is given the policy reference at intake so their own insurer can mirror-cover if desired.