Photo of the Day Rollie Free's Speed Record Attempt Practice Day V

[Graham Smith]

Bonneville Salt Flats, Utah, Sunday 12th September 1948. Speed record attempt Practice Day. JEL owner John Edgar (far left) watches as crew member Albert Held helps Rollie Free (center) refuel the JEL with a mixture of 15:1 alcohol. Albert's father, Mel Held, assists Bill DeMott (white shirt) with changing a sprocket and cutting grooves in the rear tyre to reduce wheel spin under full throttle at 108 horsepower. To further limit drag, the front fork has been smoothly taped over. None of these details could wait until the following morning of 13th September when Rollie would make his runs for the record. Rollie wrote in his pocket notebook on this day: 'Made practice runs on Salt Beds. Very good. Speedometer 148 & 149mph. Old record 136.18mph.' By this time, late in the afternoon on the 12th, the best gearing had been determined and the large Speedometer had been removed from the air stream for the next day's record attempt.

 

[bmetcalf]

The way the salt gets everywhere on the bike, I guess it didn't matter that the chain was resting on the ground.

 

[TouringGodet]

A switch of fuel from petrol to alcohol, along with high compression pistons, is enough to yield 108 HP?

 

[timetraveller]

I don't think that if 108HP was available he would have had to adopt the riding position that he did. I remember reading that he had several runs of just below the 150 mph mark before he adopted his famous prone position. Even allowing for the altitude of the salt Flats with the reduced air pressure and the rolling resistance of a salt surface an engine giving 108 at sea level should have easily topped the 150 mark. I have done 140 mph on a bike ridden to the meeting and I think Bill Thomas has done the same

 

[Flylow]

A switch of fuel from petrol to alcohol, along with high compression pistons, is enough to yield 108 HP?

I don't think so. But it sure sounds great.

 

[Bill Thomas]

I would think 80 BHP Tops,
Probably less, My road Bike was on 12 to 1 Pistons and 36 mm Dellorto carb's,
But we had 100 octane Petrol at the road side pumps then, Late 1970 s
I cheated a bit with a 3/4 MV Agusta, fairing,
I used standard gearing,
I changed gearing to = 44 rear teeth But then could only do 136 mph Average , Over a Flying Kilo,
But I am well over 6 foot and was about 14 stone.

 

[Flylow]

A big Thank You to John Edgar!! And of course Rollie Free!!

 

[William Edgar]

I don't think that if 108HP was available he would have had to adopt the riding position that he did. I remember reading that he had several runs of just below the 150 mph mark before he adopted his famous prone position. Even allowing for the altitude of the salt Flats with the reduced air pressure and the rolling resistance of a salt surface an engine giving 108 at sea level should have easily topped the 150 mark. I have done 140 mph on a bike ridden to the meeting and I think Bill Thomas has done the same

Thanks for your noted thoughts, but 108 horsepower is the correct figure. After Bonneville, and detuned for street riding, the JEL fuel was changed from 15:1 alcohol to 50-50 aviation gas and Benzol to produce 98 horsepower.

 

[William Edgar]

A big Thank You to John Edgar!! And of course Rollie Free!!

Very nice to have your noted thank you to my father and to Rollie.

 

[William Edgar]

I don't think so. But it sure sounds great.

If it wasn't 108, I would not say that it was. Trust me, and Rollie, who did the pre-record tuning after what the factory did in the build. 108 horsepower.