A 1938 Crocker small tank looks set to be the star lot of Mecum Auctions' August 18-20 sale of motorbikes in Monterey.
It's valued at $300,000-350,000.
Engineer Al Crocker founded the marque in Los Angeles in 1932.
It started out producing single cylinder bikes for speedway racing, before switching to the V2 in the mid-1930s.
The present lot is from this later era. It's of the small tank type, so named because the fuel tank was later enlarged.
The company switched to producing aeroplane parts in 1942 and never returned to motorcycle manufacturing.
This brief window of operations makes Crocker motorbikes among the rarest built in the US.
The record price paid is $385,000 for a V Twin produced just before production ceased in 1942.
Mecum comments that the sale "represents a very rare opportunity to own one of the most important and legendary motorcycles ever built."
A 1935 Brough Superior 11-50 complete with Alpine sidecar is expected to make $275,000-350,000.
It's consigned from the collection of the famous geneticist and biochemist Dr J Craig Venter.
The model is considered one of the world's most desirable motorbikes due to its rarity and the unparalleled quality of its construction.
Bonhams will auction a 1939 Brough Superior next month.
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