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1970s Kawasaki Z1 900 (Z1/Z1A/Z1B) Valuation Report

Date: August 2025

Historical Overview

Kawasaki’s Z1 (903 cc, DOHC inline-four) launched for 1972 and ran through the 1975 Z1B. It set the blueprint for the UJM superbike and remains one of the most sought-after 1970s Japanese classics in the UK. Early 1972–73 “Z1” machines (brown/orange or brown/yellow schemes) are generally the most desirable; 1974 Z1A and 1975 Z1B follow, with subtle running changes and livery updates. In 1976 the line evolved into the Z900 (A4) and later Z1000 models, which are outside the scope of this Z1-only report.

UK Valuation Summary (by condition and year-group)

Condition	1972–1973 Z1 (Early)	1974–1975 Z1A / Z1B (Late)	Example External Source (non-link reference)
Project / Restoration Non-runner or incomplete; engine/gearbox rebuilds and cosmetics required.	Insufficient verified recent UK hammer prices published (12–18 months).	Insufficient verified recent UK hammer prices published (12–18 months).	Recent UK auction records for true Z1 “projects” are sparse; where seen, most were Z900 (A4) not Z1.
Roadworthy / Presentable Running, usable bikes; older restorations or tidy riders; may have period upgrades (e.g., twin front discs).	£12,500 – £16,500	£6,000 – £9,000	1973 Z1, winning bid £16,250 (Car & Classic, 1 Apr 2024); 1973 Z1, sold £12,650 (Bonhams, Spring Stafford, 26 Apr 2025); 1974 Z1A, sold £8,740 (H&H, 9 Jul 2025); 1975 Z1 “very usable”, sold £6,136 (Manor Park, 5 Apr 2025).
Restored / Excellent Very original survivors or high-quality restorations; correct paint/trim; matching numbers and strong provenance.	£21,000 – £26,000	Insufficient verified recent UK restored examples with disclosed prices (12–18 months). Older UK results suggest mid-teens to high-teens when not exceptional.	1972 Z1 ex-press bike, sold £25,875 (Iconic Auctioneers, 7 Apr 2024); 1973 Z1, sold £21,275 (H&H, 20 Jul 2022, context). For late Z1B: well-presented UK-model, sold £8,625 (Iconic Auctioneers, 12 Nov 2023, older context).

Notes: Ranges are derived from recent UK-only verified sales. Early Z1 (’72–’73) tends to command a premium over Z1A/Z1B. Exceptional provenance (press bikes, celebrity/period-documented examples) can exceed the top of the early band. Z900 (A4, 1976) results are excluded from the numbers here to keep the scope strictly Z1 (’72–’75).

Value Influencing Factors

Matching numbers & authenticity: Correct frame/engine sequences and factory-style finishes; factory paint schemes (brown/orange, brown/yellow, later livery) and original decals.
Correct parts: OEM 4-into-4 exhausts, correct rims, instruments and switchgear; period twin-disc conversions are acceptable but absolute originality tends to score highest.
Mechanical health: Evidence of quality engine work (cams, timing chain/guides, valves), charging/ignition refresh and carb overhaul.
Provenance: UK registration history, documentation, featured bikes (press, known specialists) and comprehensive history files add tangible value.
Market timing & presentation: Spring/summer sales are typically strongest; clean, correctly detailed examples outperform over-polished or heavily modified bikes.

Conclusion

Based on verified UK sales, a 1972–73 Z1 in tidy, usable condition typically trades around £12.5k–£16.5k, with excellent/restored early bikes reaching roughly £21k–£26k (and more if provenance is exceptional). Later 1974–75 Z1A/Z1B riders commonly sit around £6k–£9k, with top-flight restored late bikes lacking sufficient recent disclosed UK results to quote a firm band in the last 12–18 months; historical UK outcomes suggest mid-teens when not exceptional.

Sources (non-link references):
• Car & Classic Auctions — 1973 Kawasaki Z1 900, winning bid £16,250, ended 1 Apr 2024 (UK).
• Bonhams (Spring Stafford, Motorcycle Sale) — 1973 Kawasaki 903cc Z1 (The Andy Chapman Collection – Part II), sold £12,650, 26 Apr 2025 (UK).
• H&H Classics (National Motorcycle Museum) — 1974 Kawasaki Z1A, sold £8,740 incl. premium, 9 Jul 2025 (UK).
• Manor Park Classics (April 2025 Auction) — 1975 Kawasaki Z1 “Very usable example”, sold £6,136, 5 Apr 2025 (UK).
• Iconic Auctioneers (Shuttleworth Spring Motorcycle Sale) — 1972 Kawasaki Z1 ex-press bike, sold £25,875, 7 Apr 2024 (UK).
• H&H Classics (National Motorcycle Museum) — 1973 Kawasaki Z1, sold £21,275 incl. premium, 20 Jul 2022 (UK, older context).
• Iconic Auctioneers (NEC, Birmingham) — 1975 Kawasaki Z1B 903cc, sold £8,625, 12 Nov 2023 (UK, older context).

All Valuations