Friday, April 13, 2012

Eric LeVine's Street Legal Land Speed Record Yamaha RZ350

A really stunning piece of engineering!  See the rest of the pics on his flckr thread here.

Eric LeVine's Street Legal Land Speed Record Yamaha RZ350

I originally built the bike in late 80'S from a thrashed, stock 1985 Yamaha RZ and ran it at the speed trials in the 1990's at El Mirage dry lake in California, and at the Bonneville salt flats in Utah. It got a few land speed records and still holds one at over 146mph (350cc un-faired class). I put it in in storage in 1997.

After 14 years in a shed in San Diego, I got it out in February 2011, revived it, did some mods (like lowering the gearing), and converted it to a weird street machine. Quick, loud, uncomfortable, and smoky.

The engine mods are Yamaha Banshee cylinders with really opened-up porting for maximum power, even sacrificing powerband. I massaged the ports and thinned out the webs between all of the transfer ports, and precisely matched the transfer ports to the enlarged case ports, and had custom gaskets made as to not impeded the flow from the crankcase into the cylinder. The head is a product from ProDesigns made for a Yamaha Banshee quad. It has interchangeable combustion chambers. I used the maximum squish/lowest volume combustion chambers they offered to increase the compression. The bottom end is basically stock Yamaha RZ with the crankshaft welded to prevent separation at high load/rpm. All of this while strictly maintaining 350cc displacement to be legal in the class. I sometimes ran Wiseco pistons, but had the best luck with stock Yamaha RZ 350 pistons.

It has 38mm Lectron Powerjet flatslide carburetors. Those Lectrons were the trick set up at the time, and Don Vesco Racing helped me set them up. TZ 350 intake manifolds were used to accept the big carbs and were modified to match the cylinder intake bolt pattern, Trinity Racing reed spacers and TDR reeds are on it. Ran SCTA-supplied VP and ERC race gas with Yamalube R premix oil at 44:1 ratio. The pipes were custom made by Rob North (legendary Triumph guy) using some patterns from Don Vesco. I ran EGT (exhaust gas temperature) gauges in the header pipes. If the gas temp got over 1100F on a run, I shut down to sort out the problem. Usually a lean cylinder for some reason. This is important when running a two stroke at wide open throttle under full load for about 25 seconds. Pistons melt real fast.

Transmission is stock, because in speed trials, the tranny doesn't get slammed around much. The shifting is very deliberate. I left the 6th gear in the bike but never used it. It is an overdrive and bogged the motor. So I geared the bike for max speed in 5th. That meant I had to increase the final drive ratio dramatically. I a custom 20-tooth countershaft sprocket. That allowed me to tune the rear sprocket gearing to the conditions (air temp, freshness of motor, tail wind, humidity, etc) and just use 5th as top gear. I recalibrated the stock neutral light to light-up when I reached 5th (because sometimes when I was going over 145 on wet salt, in a crosswind.I lost track of my gear count).

Clutch is heavy duty Barnett with stiffest available springs.

The water pump is gone (electric, see below). The oil pump is gone (premix).

The front end was raked-out and the swingarm extended by Motorcycle Dynamics in Escondido, CA. Seat is AirTech TZ 250  model.

The big aluminum tank is coolant. When raced, it had no radiator for aerodynamics so I pumped coolant with an electric water pump through the tank. It had enough water to get the bike through a run and raise the water temp to about 150F. I used the electric pump as to not burden the engine with the water pump impeller sucking power. The small tank is 1.5 gallons of fuel.

The riding position was tuned for max aerodynamics. Bikes are notoriously "dirty" aerodynamically so I tried every little thing to get the bike and the rider "cleaner". At the time (early 90's) there were lots of rules for un-faired bikes about streamlining. This funky front fender was essentially a loophole that I exploited. It is a fender, not a fairing, and did not protrude side-to-side far enough to shield the rider from the wind..and it seemed to work well. Now the rules do not allow any device that attempts to direct air around the bike or rider..unless running in the streamlined class. It also has a skinny Goodyear drag racing front tire to lessen the frontal area, and reduce rolling friction. I ran the fastest with low tire pressure in the rear.about 20 lbs.

These were all experimental attempts to gain another MPH. That is the beauty of LSR. It is pure, amateur, and promotes ingenuity. Just like that movie "World's Fastest Indian".it's about trial and error, learning from others, speed, noise, and the fun of it all.

Now it is just fun to ride occasionally to Vintage/Café bike rallys in the Seattle area.







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