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Douglas MK3 - Doug Kephart


Douglas MK3 motorcycle
The post-war Douglas MK3 was the first all new design to issue from the British motorcycle industry after the war. The engine was derived from a small generator set developed for the military during the war.

My Mk3 was an original export to the USA, first going to New York in 1948 and is the seventy-fourth off the production line. Not many post-war Douglas models were shipped over stateside. Less than fifty in total and most of those were of the previous T35 model, and went to the West Coast. They lacked proper dealer support here, and most folks wanted something larger than a 'mere' 350cc.

(click on pictures to see a larger view)

What happened to mine between then and 1986 I do not know, but it was in a very dilapidated condition when I purchased it for $475. It had been in a front-end collision that bent the frame, which was also fractured in five separate places. The heads were missing and the sole remaining cylinder damaged beyond repair.

Eventually all was put right, and missing items sourced through the London Douglas Motorcycle Club. However in hindsight it is a strong argument for spending a bit more money and starting out with something a little better!

Douglas MK3 motorcycle

Douglas MK3 motorcycle - closeup



Douglas MK3 motorcycle closeup


Due to the very poor condition and repairs to the frame that could not be concealed, a conscious decision was made not to worry about originality. Stainless-steel rims had not quite yet become available, and the chrome rims at the time had a very poor reputation. So I used aluminum Akront rims and stainless-steel spokes. I liked the maroon color of the later 80 Plus model Douglas, and chose a similar shade. I modified a spare timing chest cover to improve crankcase ventilation (a design fault) and added the drive and tachometer at the same time.

I have never obtained the advertised top speed of 73mph, but I did see 70, the last few miles per hour were very slow in coming! But it will buzz along at 60mph for long stretches; not till 65mph does the engine start to feel 'strained'. Definitely an engine that needs to be 'kept on the boil', the limited horsepower available does not make a major appearance till after 4000rpm.

Handling is surprisingly good, mainly due to a very low center of gravity, and not to an excessively rigid frame! The rear swing arm is linked to torsion bars concealed in the lower frame tubes. The front forks were originally slated to also be torsion bar suspension, but were replaced by a similar leading link design controlled by simpler internal coil springs. These had an unheard of six inches of travel, in a time when girder forks still reigned supreme and rear suspension was rigid.

The good handling is fortunate, as you can maintain your hard earned speed through the turns. Acceleration is modest. It is an easy starter. Even after sitting all winter, flood the carburetors and it will likely start or at least try on the first kick.

Particular problems with the Mk series are carburetor bodies are getting scarce. The mounting flange studs are oriented vertically where most all other #274 Amals used a horizontally oriented flange. After-market pistons tend to pass a lot of oil, particularly visible during warming up. There have been substitutions with pistons from Japanese motorcycles that seem to work better. Most expensively, crankshafts do not often obtain high mileage between rebuilds. Particularly newer rebuilds by a well known firm!


Douglas MK3 motorcycle


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