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7 comments

Setting a Land Speed Record: Preparation (Part 4)

Posted November 11, 2011 12:01 AM by Old_School

On Friday morning, my team and I arrived early at the airfield and set up our pit area. That was when we discovered an interesting fact about racing: it doesn't matter how early you THINK you are, there are always 10 other people who camped at the track and were up at dawn staking a claim. The tent went up and we spent a few hours getting settled and meeting the other racers before tech inspection opened. The variety of machinery present was staggering. Everything from heavily modified Studebaker Hawks to vintage Honda cubs was being rolled out, tweaked, and coaxed to life. The ingenuity extended to the support vehicles as well. Right beside the massive campers attached to two-story car trailers were school buses converted to motor homes. The racers were just as diverse!

Tech inspection opened before lunch and my bike went through without too many problems. Besides having to redo the lock-wires on all the screws, it passed with flying colors. I spent the afternoon performing final touch-ups and attended the drivers meeting and track inspection at 5:00 p.m. It wasn't until we all drove the length of the runway that I gained an appreciation for its sheer size. I never imagined that an area so large, flat, and empty could exist. You cannot understand it unless you see it in person; however, I'm sure it doesn't compare to the Bonneville Salt Flats.

Saturday was the first race day, and once again we learned that it is impossible to be first in line unless you spend the night. Arriving at 7:30AM, there were at least 40 vehicles ahead of us. Unfortunately, there was a persistent headwind all day that impacted the times.

The first run was a disappointment. No matter what I did or how small I made myself against the wind, it could only manage a 42 mph pass. The headwind clearly played a significant role because I could hit 50 mph in the return lane with the wind to my back. However, according to the math, the bike should have been able to attain 55 mph with its current gearing. I returned to the pit to find the problem and try to squeeze the extra speed out. It wasn't until the bike was up on the lift that we discovered that the front disc brakes were severely dragging, so I decided to put the machine on a major diet and try again.

Within an hour, I had removed the brakes, master cylinder, front fender, taillights, and whatever other small parts weren't required by the rules. As a result, the top speed on the next run immediately improved to 50.2 mph. By increasing the throttle stop and altering my riding position I was able to incrementally increase the top speed during every subsequent run. The final top speed, recorded during the last pass, was 56.535 mph. As of now, that speed stands as the official record for a 350cc non-streamlined motorcycle. I've already begun the modifications to improve on it next year.

Photo Credits: Daniel Falkenstrom

Editor's Note: Just joining this series? Then check out:

Setting a Land Speed Record

Setting a Land Speed Record: Preparation (Part 1) - Electrical

Setting a Land Speed Record: Preparation (Part 2) - Engine and Drivetrain

Setting a Land Speed Record: Preparation (Part 3) - Preparation

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Guru
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#1

Re: Setting a Land Speed Record: Preparation (Part 4)

11/11/2011 7:14 AM

Excellent...
Yeah brakes are hugely over rated.
I bet it was a real buzz seeing all the other machines and chatting with the participants.
What do you plan next to tune up that sucker?
Del

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#2

Re: Setting a Land Speed Record: Preparation (Part 4)

11/11/2011 8:07 AM

Good job trimming it down to 'fighting weight'!

Might I suggest some further ideas...

Only the bike has to be non-streamlined.

If you can find a tighter fitting set of leathers to borrow...1 mph.

Scoot back on the seat and lean down lower so your chest just touches the tank...add 1 mph.

Scooting back on the seat should also allow you to pull you knees in a bit also.

Cut the back 10" off the rear fender to get it out of the 'wind' ...a tenth or two

Peel the cover off the seat and take an electric fillet knife and carve an inch or two off the top of the seat foam to lower your overall body height...half a mile an hour.

Find some cafe handlebars or straight 'drag' bars and put them on to get your arms down...half a mile an hour.

Buy 'World's Fastest Indian' and watch it whenever your enthusiasm wains!

Good luck!

Also, Cushman Eagles used a heavy duty centrifigal clutch that was indestructable.

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#3
In reply to #2

Re: Setting a Land Speed Record: Preparation (Part 4)

11/12/2011 11:02 AM

probably some clip-ons [handlebars that mount to the forktubes]

rear set foot pegs too

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Commentator

Join Date: Jul 2009
Location: Upstate New York
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#4
In reply to #2

Re: Setting a Land Speed Record: Preparation (Part 4)

11/13/2011 9:56 AM

The picture of me riding was taken at the beginning of the course. After I passed the first markers and moved over to the center line, I tucked in and crouched down like you suggest. Actually, i was down so low that I could not look forward, so I had to watch the guide line on the runway below me to "see" where I was going. And I'm not planning much more modification to the frame of the bike because I want to keep it road legal and relatively stock. Although, I am planning to install a transmission, but I am still working out the details on that.

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#5

Re: Setting a Land Speed Record: Preparation (Part 4)

11/13/2011 11:57 AM

I'm curious about the make, model and horsepower of the engine.

Also, what kind of tire pressure you were running and were the tires radial or bias ply?

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Commentator

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#6
In reply to #5

Re: Setting a Land Speed Record: Preparation (Part 4)

11/27/2011 11:04 PM

Its a 6hp Yanmar clone from Ebay, and I am not sure what kind of design the tires are. I chose them for their round cross section and unbroken center tread to reduce rolling friction.

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#7

Re: Setting a Land Speed Record: Preparation (Part 4)

11/28/2011 6:32 PM

http://phors.locost7.info/phors06.htm

This is a sample formulation for a Corvette but you may be able to re-calculate for a motorcycle which would have about 6 square feet of frontal area but a Cf of around .55 because of the lack of streamlining on the 'naked' bike.

My bicycles have hugely different rolling resistance even with the same tires and tire pressure because of the quality in the wheel bearings and the type of bearing grease.

I'm not sure if a transmission is going to add to your top speed unless you were still accelerating when you went through the trap.

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