Description
This motorcycle is Lot 243 to be auctioned by Bonhams at The Spring Stafford Sale (The International Classic MotorCycle Show) on April 25th & 26th, please see the Bonhams Motorcycles Website for full details.
Auction Timings:
Lots 1 - 94 are to be sold from 14:30 on Saturday 25th April 2026.
Lots 201 - 353 are to be sold from 11:30am on Sunday 26th April 2026.
Public Viewing:
Available 25th & 26th April 2026 from 09:00 until 17:00, at The Staffordshire County Showground (The International Classic MotorCycle Show).
The David Plant Collection
** 1921 Norton 633 Big Four**
Registration no. EY 1265
Frame no. 3084
Engine no. 20681 (see text)
Norton relied on proprietary engines in its formative years - winning the inaugural Isle of Man TT with a Peugeot-engined machine - before introducing its own design of power unit in 1907. The long-stroke (82x120mm) sidevalve single displaced 633cc and the new model it powered became known as the 'Big 4'. Smaller capacity versions followed and in 1911 the 500 adopted the classic 79x100mm bore/ stroke dimensions which would characterise the half-litre (actually 490cc) Norton for the next 50 years. Norton's sidevalve engines were revised for 1914 and in 1921 the Model 16, as it had become known, received a new lower frame, becoming the 16H. Considered by many to be an ideal sidecar 'tug', the Big Four (and 16H) would be continuously up-dated for the next 30-plus years, many seeing service with Allied forces in WW2. Post-war, the Big Four was revised with a shorter (113mm) stroke for a capacity of 597cc before taking its final bow, alongside the16H, in 1954.
This Big Four is an older restoration that has belonged to our vendor since 1983. It should be noted that the gearbox is stuck and we have been unable to test for compression. Offered with old/ current V5/ V5C documents. It should be noted the accompanying documents list the engine number as 20661 opposed to 20681 (a typographical error).
Following a period of inactivity, this motorcycle will require recommissioning and/ or restoration to a greater or lesser extent before returning to the road and thus is sold strictly as viewed. Prospective purchasers should satisfy themselves with regard to this motorcycle's completeness, history, authenticity, originality and mechanical condition prior to bidding.
Key not required
All lots are sold ‘as is/ where is’ and Bidders must satisfy themselves as to the provenance, condition, age, completeness and originality prior to bidding. Visit the Bonhams Motorcycles website for all pertinent auction information.
