[beatr911]

One of the issues for the Vetter Challenge that is being discussed in various places is deciding which platform, or donor bike to use. Some people want to use thier existing bike, some want to get the "best", some want the cheapest and most common. This whole bike choice thing will probably never be resolved completely as the optimum existing bike doesn't exist to suit everyone. We only have what is out there now to choose from. The best we can do is get one that is good enough for our purposes, or slightly modify one towards optimizing it for the purpose of high MPG.

The important technical factors in choosing a donor bike appear, in no particular order, to me to be:

• Highly efficient motor, about 250cc seems good, some are better than others.
• Chain drive, ability to change gearing, and chains are more efficient than CVT and shaft drive.
• Low seat height, reduces frontal area and corresponding total drag. IIRC 24" is the lowest legal height in most states, though I've NEVER heard of someone being ticketed for too low of a seat.
• Air or water cooling. Water cooling allows higher compression ratios and being able to place radiators where you want them among other things. Air cooled are simple, non-toxic and noisier.

There are also non-technical and practical factors like:

• Common availability. Hard to find out of production bikes may fit the bill, but only for the select few that can find them.
• Cost. This threshold varies from person to person.
• Ease of modification. Some bikes will be easier to modify than others for mpg and aerodynamic goals.
• Chinese. Some don't want to send money to them, some don't care, some question thier reliability. It's up to you. Darn inexpensive, if you wrench your own rides.

Craig is thoughtfully trying to design something that could be used on many different motorcycles. The Vetter streamliner front fairing blocks alot of wind so water cooling with this would probably be needed.

Alan's Ninjette with only the Vetter tail actually gets better mpg than Craigs fully streamlined Helix. Whether this is due to a more efficient engine and/or drivetrain or some other factor hasn't been dithered out yet. It does demonstrate however, that an un-optimized front fairing can still work with a good tail section. This discovery may open up some choices to include an efficient air cooled engine with a minimal front fairing and a tail, as I see it.

Below is a list of some of the more common freeway-capable bike choices and salient features that have been posting 80+ mpg figures. It's not a complete list as you all will have additions, I'm quite sure.

• Kawasaki Ninja 250 (1986 through '07 are best). Very efficient water cooled motor, very common, very cheap, changeable gearing. High strung motor not optimized for low speed operation, higher than optimal seat height, cramped sportbike leg position for some.

• Honda Helix 250. Pro: Craigs paved the way! Average motor efficiency, water cooled, super easy to ride, common, cheap, changeable gearing available through only one source, low seat height, comfortable, Chinese copies still made. Tiny 10" wheels, inefficient CVT transmission.

• Honda NX250. '88-'89 I think, very efficient water cooled motor, changeable gearing, comfortable upright seating. Hard to find, high seat height, hard to find, doesn't have common street tire sizes, hard to find.

• CBR250R. Since 2011, very efficient low friction water cooled motor designed for mid range, feedback fuel injection, changeable gearing. New, expensive (relatively), few in resale yet, high seat height.

• Yamaha V-Star/Virago 250: Since 1988, Very efficient long stroke air cooled motor, common, cheap, changeable gearing, tolerates taller gearing well, comfortable low cruiser seating, Chinese clones are cheap. It's air cooled.

• Honda Rebel 250: Since 1986, Efficient air cooled motor, common, cheap, changeable gearing, comfortable low cruiser seating, most cramped small cruiser. It's air cooled.

• Suzuki DR200/Honda CRF230/Yamaha XT225/TW200/Chinese 200 dual-sports and Motards: Lumping these together as they are very close in performance and mpg results. Efficient air cooled motor, common, cheap to very cheap, changeable gearing, comfortable upright seating, torquey durable motors. Tall seat height, 15-17hp is JUST BARELY enough without aerodynamics, air cooled motor.

What is your favorite among these?

Keeping the availability, cost, practicality issues in mind, can anyone think of a better bike platform for the Vetter challenge other than these? If so, please post.

-Garth