Saturday 27th & Sunday 28th February: All tracks open from 9.00 until dark. Trail tracks are in good condition and are a great option to avoid the heat. The MX track is dry and a bit powdered in places but people are still enjoying the ride and the jumps!


The Air Scoop

Before Water Cooling

maddix park mx


On the dawn of water-cooling, riders were looking for ways to control heat build-up in their air-cooled cylinders. The most successful idea was the DG Pro-Flow air scoop. It was a simple air scoop that attached under the gas tank and down over the fins of an air-cooled cylinder. At speed it increased air velocity through the fins by virtue of the Bernoulli Effect. The inventor was Jody Weisel.

The top photo shows the Pro-Flow scoop mounted to an air-cooled 1980 Honda CR125. It may be hard to imagine, but 33 years ago all bikes were air-cooled. Eventually water-cooling eliminated the need for air scoops, although 500cc bikes stayed water-cooled for much longer than 125 or 250 two-strokes.

Although this bike says Derbi on it, it is actually a modified Suzuki RM250 with both a Pro-Flow scoop on the side of the engine and an air scoop front number plate.

Honda and Yamaha both decided that the Pro-Flow scoop was a good enough idea to copy. This is the production air scoop on the 1984 Honda CR500.

The 1987 Yamaha YZ490 came off the showroom with a black plastic air scoop. We asked Jody if Honda and Yamaha paid him royalties for using his design. He just laughed and said, "The air scoop was just a last-ditch effort to cool bikes that were rapidly getting more powerful and generating more heat than the finning could control. As with most ideas, I wanted to do something for my own race bike and was happy that other people could use it also. Neither Honda nor Yamaha were going to stick with air-cooling for very long, so I took pride in the fact that they liked my idea."

This article is part of Motocross Action Mag's series of Gyro Gearloose Inventions of the Day.


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