The 390 Stamp
A hand-stamped aluminum frame-tab pressed into the steering head crown, carrying the build's serial number. The tab is the legal anchor of provenance — the moment a machine becomes a numbered Series 390 specimen.
Series 390 · The Process
The 11-Month Rebuild
A frame-off restoration of a 1969–1975 Kawasaki two-stroke triple is not a service interval. It is an engineered, eight-chapter sequence — paced across eleven months, signed with a numbered frame-tab, and closed with a ninety-six-page bound dossier. This page is the inside of that sequence.
Eight Chapters
The chapters, in the order they happen.
Every Series 390 build moves through the same eight engineering phases. No chapter is parallel-tracked, no chapter is skipped. The sequence is the contract.
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01Intake
Intake & Provenance
The machine arrives at the atelier, is photographed against a calibrated grayscale target, and matched against the Kawasaki Heavy Industries Akashi archives we hold correspondence with. Originality targets, donor-sourcing rules, and the customer's intended use are written into a build sheet signed by both parties.
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02Strip
Frame Strip & Catalogue
Every fastener is removed, bagged, and labeled. Every component is photographed on a copy-stand and catalogued to a sub-millimeter inventory. Frames are chemically stripped to bare metal — never media-blasted — so weld porosity and original factory stampings survive.
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03Metal
Metalwork, Welds & Tab
Frame rails are checked against the factory jig. Repair sections are hand-formed and TIG-welded. The numbered Series 390 frame-tab is pressed into the steering head crown — this is the act that defines the build as a numbered specimen, not a refurbishment.
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04Powder
Powder, Paint & Livery
Frames are zinc-rich primed, polyester-powder coated, and finish-painted to period-correct livery. Fuel tanks are chemically stripped, sealed with modern two-part epoxy, and finished in OEM-matched codes verified against Akashi paint-chip references.
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05Engine
Engine Assembly
Three of our seven technicians are factory-certified two-stroke engine builders. Crankshafts are balanced, third-member bearings replaced, and cylinder assemblies are measured for port timing against a Series 390 spec card. Every fastener is torqued to a sequence documented in the dossier.
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06Reassembly
Trim, Electrics & Reassembly
Harness, switches, gauges, control cables, and chrome are reunited with the frame. Wheel bearings, brake shoes, and control dampers are replaced. Every electrical circuit is tested against a schematic, not a guess.
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07Dyno
Dyno & Validation
Each engine is run on our in-house dyno for a full two hundred hours — a deliberate break-in protocol, not a single pull. A leak-down compression chart is taken at the close of every chapter of the run. Numbers below threshold fail the build back to Chapter 05.
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08Crate
Crate & Dossier
The build is wrapped, crated in an ATA-spec ISPM-15 timber case, and the ninety-six-page bound dossier is printed and signed. The dossier is the inheritance document: provenance, dyno, torque records, paint codes, photography, and a notarized 390 Stamp certificate.
What Ships
What a finished Series 390 build ships with.
Four physical objects. Each is named, numbered, and travels with the machine in its crate.
Provenance Certificate
A notarized certificate binding the 390 Stamp number to the chassis, engine, and customer of record. Required by Hagerty's specialist-referral network and accepted by major US, UK, EU, JP, and AU insurers as primary provenance.
200-Hour Dyno Report
The complete two-hundred-hour dyno log: pull curves, AFR traces, cylinder-by-cylinder temperature, oil-injection rates, and a final leak-down compression chart. Signed by the dyno technician and the master mechanic.
96-Page Bound Dossier
Archival-grade smyth-sewn book: provenance, all eight chapters documented, dyno, paint codes, fasteners, before-and-after photography, technical correspondence, and a numbered table of contents. Printed on Munken Pure paper, hand-bound in Portland.
From the Bench
Four specimen plates.
Documentary photography from current and recent benches. Grain-tolerant, warm-sepia, no stylized overlays — the machine speaks.
The Cycle, Verified
The cycle, in numbers a collector can verify.
11mo
Average rebuild cycle, intake to crate
38%
Faster than the next-quickest independent marque specialist
92%
On-time delivery rate across the last 24 builds
71%
Customer retention across repeat restorations
40+complete frame-off rebuilds delivered to date
200hours of dyno run per engine, signed in the dossier
96pages in every bound handover document
11countries on four continents, crate-delivered
Questions
Five questions collectors ask before reserving a build.
The honest answers, in the same order we hear them.
How long will my build actually take?
Eleven months is the average across our last forty builds, intake to crate. The honest answer for an individual build is — it depends on parts scarcity, the donor machine's condition at intake, and paint sub-contractor lead time. We give an estimate, not a promise, and we publish the chapter-by-chapter schedule in your build sheet so you can see slippage the moment it occurs.
What does the deposit structure look like?
Reservations are taken against the next available bench slot with a non-refundable build allocation. The build is paid in four chapter-gated milestones: intake, frame tab, paint livery, and crate. Each milestone is invoiced only after the prior chapter's deliverables have been signed off by you in writing.
Can you ship internationally?
Yes. We have crate-and-shipped completed restorations to eleven countries on four continents, in ATA-spec ISPM-15 timber cases via insured specialty freight. Crating, customs paperwork, and freight are quoted separately and listed in your build sheet before Chapter 08 begins.
Will my insurer accept the 390 Stamp?
We have been AAA-rated by Hagerty's specialist-referral network since 2020, and the notarized provenance certificate bundled with every 390 Stamp is accepted as primary provenance by major insurers in the US, UK, EU, JP, and AU. We provide a specimen certificate before you commit so your broker can pre-clear the documentation.
How do I start?
Send the chassis and engine numbers of the donor machine — or a photograph, if it is still a candidate — to [email protected]. We reply within two business days with intake availability, an estimated cycle, and a specimen copy of the build sheet so you can read the contract before you sign it.