RD250 LandSpeed Project

RD250 Land Speed Bike

I've wanted to build a good RD250 based project for some time so when I started contemplating my "One Last Time project" naturally An RD250 LandSpeed bike came to mind.

The concept.

The first step after taking off every possible tab and bracket from the frame that isn't being used is to get the bike lower and longer. I could have chosen a swingarm off one bike, a wheel off another bike and brakes off something else but by using a complete GS500 rear end it gave me a wider 17" wheel, a longer swingarm, and a ready to go brake system. Time and money saved here can go a dozen other well needed places.

Some classes require you to reduce the turning radius for safety reasons so here's a simple way to determine how much material you need to add to your steering stops.

One of the things that will be different about this project is that I'll be shifting the tank back into the empty space that's usually under your chest and stomach. This is going to require a custom tank but it will drop my riding position a few much needed inches. To break 150mph on an RD250 is going to take every trick in the book.

I mocked up the basic size of the tank out of some wood I had laying around here. Then made a "cardboard tank" closer to the shape I thought would be about right with an open top. Then I lined it with a plastic bag and poured in the required 1.5 gallons. I had 1 1/2 inches of extra space from the top so I made a new cardboard tank lower, a little wider in the front and a little narrower in the back from what I'd learned from the first one. I tried the bag of water trick again and it dropped right in.. perfect, Then I made one last “wooden” tank to this shape just to make sure that the fit was just right. Now that I have a pretty good idea of the size and shape off we go to make the tank..

Using my daughter Sophia to check tank fit and riding position.

Brakes and shifter
It's also kinda important that the bike shifts and stops so I need to make a shift lever and a brake lever. It's not that complicated. 1) figure the distance you want between the pivot to the piece your toes will push on in my case it was 5 1/2". Make one of these out of 5/32 particle board put it on check the fit and determine at what angle you need it (in this case it put the toe piece at 8" above the ground) and write it down. next make the second part of the lever out of particle board put it, position it where it needs to be and mark the two in relation to each other so that you can line it all up when it's off the bike.
When figuring out where you want the second lever remember that any time the lever isn't at 90 degrees to the rod then some of the movement is pushing up or down and not the desire forward and back. So for the shifter at rest you want 90deg to the shift rod, on the brake you can start a little further back than 90 so that the lever is reaching the optimum 90deg as it's doing the most work.
Now cut it all out of steel or Ali, weld em up and bolt em on!

Making temples first allows you to make changes before you start cutting steel. See how here I'll shorten the upper lever a little bit on the final version.

Preparing the cylinders
A LOT of time is spent here! Designing using the latest design software.. Long hours designing into the night, researching and discussing with a group of really wonderful fellow tuners, Sectioning cylinders and test grinding on spare cylinders.. and then grinding, grinding, grinding..

Pistons
Pistons were an issue.. There just wasn't a drop in performance piston available for the RD250 yet. Todias Wossner stepped up and between him, myself and a lot of help from some really world class two Stroke men now there is.

Building the pipes

Ready to Race

The Worlds Fastest RD250 143.767mph

A special thanks to Tom Turner, Neels van Niekerk, Tobias Wossner, John Ritter, Wobbly Wright, Frits Overmars, Ed Miller, Tom Mackie, Mark Atkinson, Scott Clough (Scott Clough Racing), Andrew Green, Brad Heiter, Allen Knowles (CT Racing), RD James, John Dumas, Mark at R&D Motorsports, Ralph & Gabriel at Superior Performance, Lucas Dunev, Roland Sands, Tony Doukas and Wayne Welch.