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Features

The CR/CRTT Harley Sprint

Amazing machinery

By Matt Cuddy

 


 

     THE AERMACCHI-HARLEY DAVIDSON SPRINT CR/CRTT

In 1961 Harley Davidson started importing Aermacchi 250cc bikes in hopes of making a dent in the small bore market that was growing in the USA at the time. Remember, Honda, Yamaha, Suzuki and Kawasaki had already started making in-roads on the mighty V twin Harley, and HD didn’t want to be left out of a potentially lucrative market segment, the small light performance oriented motorcycle.

 The Aermachhi 250 Sprint was to be one of the more successful Italian imports that Harley brought over in the 20 or so years it owned Aermacchi, with a pretty good record in the reliability and power department, unlike most Italian bikes of the time.

The Sprint series utilized a horizontally disposed cylinder configuration (think Honda 90) with an over head camshaft, and two large valves. The 250 would grow to a 350cc configuration in 1966, by punching out the cylinder, and giving it a longer stroke.


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1966 Sprint ERS, set up for what looks like Motocross...

The Sprint was a nice sedate street bike, and some were configured for dual-purpose duties. But the Sprint we’re going to concentrate on is the Sprint CR, the racer that started off many flat track champions on the road to the winners circle.

You didn’t purchase a Sprint CR/CRTT as a complete motorcycle. When you went to the Harley dealer and plunked down your hard earned bucks, all you got was an American Made DT frame, front forks, alloy racing wheels (without
tires) with a gas tank, solo seat and rear fender thrown in. And depending on what time of the year you ordered your Sprint CR, you might have to wait for a motor to be assembled and shipped from the Aeramacchi factory in Italy, with Harley Davidson stamped on the side cases.

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Differing top ends to the two different motor configurations. Look at the size of that big end on the crank! Gigantic. Ran on needle rollers too.

Aermacchi produced two motor configurations for the CR/CRTT Sprint. The first motors were undersquare, at 66 x72mm and were produced from 1961 to 1965. The second generation CR/CRTT motor used a “short rod” design that made the motor “oversquare” with a bore and stroke of 72 x60mm, used a dry clutch, Bendix Scintilla Magneto and was available with 4 or 5 speed gearboxes.


SprintCRriteEngine[1].jpg
1963 "Longrod" motor, about 35 hp @ 9,000 rpm. Notice the dinky carb.

The shortrod motor could spin up to 10,500 rpm, and was a better motor for road racing, or longer dirt tracks, while the longrod motor did better on ½ to 1/8th mile ovals. Both motors had to be de-tuned to run on a 1/8th mike track, as they had radical camshafts and high compression pistons.

The bikes started out with dinky 27mm Del Orto carbs, with a rubber mounted remote floatbowl (vibration maybe?) but tuners who ran the bikes understood that the motor could take a much larger carburetor, even 1 & 3.8th inch Amal GP road racing carbs were fitted to the 250 with great success. It was quite a strong motor design which offered the rider a lot of room in tuning the bike to his own specs.

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Gene Romero on his CR

Gene Romero, Bart Markle, Carroll Resweber and Joe Leonard all started on the Sprint CR/CRTT dirt tracker, and it even won the Daytona 100 road race in 1963 at the hands of Rich Hammer. Now these guys had real racing names if you ask me.

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A kit bike from 1963 in its original configuration. Notice the DT rigid frame, 200 lbs wet.

The last Harley Davidson sprint rolled out of the Aeramacchi plant in 1973 replaced by the two-stroke enduro and MX 250 bikes. By 1974 Harley divested Aeramacchi to the Castogolgni Brothers, who started Cagiva from the ashes of Aermacchi.

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A barely used 1970 Sprint ERS. One out of 102 units made by the factory for racing. Rare stuff. Notice the lump on the right side case for the magneto.

So when you think of those ugly chrome festooned Italian Harleys of the early sixties, don't forget the ones that won races, and launched some of the greatest riders of all time.

The Aermacchi/Harley CR & CRTT.