Sunday, May 16, 2021
Friday, May 14, 2021
Thursday, May 13, 2021
Wednesday, May 12, 2021
This motorcycle project was featured in the December 1990 issue of Classic MotorCycle. Don Brown had done some work on the engine of his Douglas flat twin and visualized a conversion to four cylinders by stacking a second motor above the original. It apparently went together logically and the crankshafts were coupled together on the front of the engine using an larger diameter idler. The upper engine does not use a flywheel.
It seems an unconventional solution and looks a little odd. At least he didn't pull the BMW trick of installing a VW Bug motor. I've not ever seen a Douglas engine apart so I can't visualize how this was done, in fact I think I've only seen one Dragonfly in my life!
Tuesday, May 11, 2021
Monday, May 10, 2021
Sunday, May 9, 2021
Mrs Jennison storms up Bwich-y-Groes on her Brough Superior during the 1923 ACU Six Days Trial. Mr Jennison minding the route cards. Mrs Jennison liked her fast motorcycles, the family was all involved.
She held a record of 70 mph on a 200cc Velocette in 1922. About the Brough, she said "It's not a beginner's motorcycle, the motor is a big lump of joy. If it doesn't break your neck it will break your heart."
Also, (and I know this audience might disagree about this statement on motorcycling in general), she said, "Even though you might be wet-through at the end of the day, there are feelings of well-being that just can't be duplicated by crocheting."
Saturday, May 8, 2021
The French Longuemare, introduced in 1901, was billed as the first automatic carburetor. A big improvement over the previous attempts, it introduced the idea of a jet that was designed to spray fuel into the airflow. A float chamber kept the fuel level at the correct level in the choke tube, fuel was drawn in through grooves in the nozzle (L). Different nozzles with more or less grooves provided some measure of adjustment. Now we're getting somewhere, though it was really only tuneable for a narrow range of speed and engine rpm. The above sketch shows the basics.
The Holley engine company immediately obtained a license for the United States as the two pages below show. The Longuemare below seems rather more complicated than the sketch above with different jets for different speeds. The plunger in the top of the float chamber would seem to be a tickler to flood the carb for starting.
The Krebs that is mentioned was a similar-type carburetor that used a complicated system involving air valves, and a diaphragm acting against a spring.
Friday, May 7, 2021
In the town where I grew up, the Yamaha dealer sold about a zillion of these things, it was a starter bike for a whole generation. A perfectly good bike with power enough, but overshadowed by the RD 350 and 400. The engine, based on the XS250, was hugely oversquare at 69 x 52.4 but redline was 9500, same as the other 400s of the day.
Thursday, May 6, 2021
Hohner commissioned John Vassos to redo the look of their harmonica for the 1933 Chicago World Fair. The result was this sleek art deco-styled Echo Elite. Production was stopped when Hohner geared up for munitions during WW2. The design was popular enough that production was restarted after the war.
From the German magazine Hobby.