Harley-Davidson Big Twin Flathead
Harley-Davidson's workhorse from 1930-1948, the Big Twin Flathead's reliable side-valve design powered riders through the Depression and WWII. It's now a collector's item prized for its connection to that formative American era.
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6 listed in the past year. The last was 3 weeks ago.
Harley-Davidson Big Twin Flathead prices by year
Auction sales in the last 3 years; prices leave out salvage and other branded titles.
Listings
The Harley-Davidson Big Twin Flathead, produced from 1930 to 1948, was the company's workhorse engine through the Great Depression and World War II. It was available in several displacements, with the 74 cubic inch V and VL models starting the series, later replaced by the U and UL models in 1937. Its simple side-valve design was reliable and easy to maintain, making it a favorite for civilian riders and military use.
Collectors value the Big Twin for its direct connection to a formative era in American motorcycling. It's a pre-war icon that represents the final evolution of Harley's side-valve technology before the widespread adoption of overhead-valve engines like the Knucklehead. Because so many were customized or ridden hard, finding a stock, numbers-matching example is a significant challenge that drives collector interest.
Buying Tips
- Verify the engine and frame numbers are matching for the year. Also check that the two crankcase halves have matching 'belly numbers'.
- Inspect the cylinders and heads for cracks, especially around the spark plug holes and valve seats, as overheating was common.
- Check the frame for modifications or repairs. Many were chopped or altered, and a stock, uncut frame is much more desirable.
- Assess the 3-speed transmission and foot-clutch setup. It should engage smoothly, as rebuilding these units can be difficult and costly.
48 Harley-Davidson Big Twin Flathead vehicles have been tracked across auctions and listings on Hypercars, with 5 currently live.
Data sourced from auction results and dealer and private listings, including Bring a Trailer, Cars & Bids, Mecum, RM Sotheby’s and eBay Motors. Updated daily.
Frequently Asked Questions
How many Harley-Davidson Big Twin Flathead listings are for sale right now?
There are 5 Harley-Davidson Big Twin Flathead listings currently live across auctions, dealers, and marketplaces tracked by Hypercars.