Page 21 - LHR Biker September 2025

horsepower in racing.
A few technical features set the Model
90 apart: OHV with twin exhaust
ports, and hairpin valve springs.

The engine used a polished I-section
connecting rod, well-machined
barrels, wet sump lubrication, and
had optional compression ratios (7.0 :
1 with optional higher ratios) for
racing.
The bike came with a 3-speed
gearbox in catalogued versions.
Works racers sometimes had 4
speeds.
Frame and cycle parts were of high
quality, with single cradle steel
frames, girder forks in front (Druid-
pattern), rigid rear with a spring-
loaded saddle.
Sunbeam also updated the styling:
early Model 90s had “flat tank” fuel
tanks. In 1929, most catalogued
models got the saddle tank, which
influenced both rider position and
aesthetics.
Racing Triumphs: TT, GP Wins,
Belgian GP at Spa, 1929The Model
90 was not merely for show—it was
built and tuned to win. Sunbeam’s
racing record with the Model 90 is one
of glory:
Senior TT Wins: Charlie Dodson won
the Isle of Man Senior TT aboard a
Model 90 in 1928. He won again in
1929. In 1929, the Model 90 was the
last two-valve pushrod machine to
win the Senior TT.
Team Prize at Isle of Man TT: In 1929,
not just individual wins, but Sunbeam
also secured the team prize because
all machines entered finished.
Grand Prix Victories: The 1929
season was especially strong. The
Model 90 is credited with victories in
the Belgian Grand Prix at Spa, as well
as GPs in Germany, France, Italy,
Hungary, plus other international hill
climbs.
The Belgian Grand Prix win at Spa in
1929 helped underline Sunbeam’s
international competitiveness. Spa-
Francorchamps, known for its fast,
flowing, and dangerous circuit layout,

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LHR Biker Magazine October 2025