Thread: Wr250x
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Old 02-26-2011, 07:56 PM   #15 (permalink)
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redyaris - '07 Toyota Yaris
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Originally Posted by derangedhermit View Post
First post, glad to be here.

I have a Yamaha WR250X - factory pics here.2009 Yamaha WR250X Gallery

It has a water cooled fuel injected 250cc engine. 6-speed manual transmission.

It gets around 60 mpg stock. I would like it to get 100 mpg when cruising in 6th. It seems to me the main area to address is CdA. I was thinking of:
- lowering it by reducing the suspension travel and ground clearance from 10" to 7" or so
- putting on a fairing, something like the Can-Am 125cc fairing at LANDSPEED, LAND SPEED RACING, SALT RACER, BONNEVILLE, EL MIRAGE, FAIRING, SEAT, FENDER, SCTA, but with lights, and with mirrors behind the fairing
- doing some fuel tuning with a Power Commander (although I doubt there is much to be gained)

The exhaust has a catalytic convertor, but no lambda sensor.

I'm not sure what changes are most effective on motorcycles. (I have been to Vetter's web site). Maybe:
- Cover the rear (laced spoke) wheel with dish covers
- Make sure there is no brake drag
- Bearing grease and engine/transmission oil - how much difference can this make?
- Gearing - it is easy to change the final drive ratio by changing sprockets. What would I shoot for?
- What else?

EDIT: What I would really like for the fairing is to make it out of a stretch fabric, like BMW did on one of their concept cars.
To start with I have a WR250R with the bigger wheels 21' front and 18' rear. The R is undderpowered in top gear and therefore a good candidate for aeromodding. I have a 14T front sprocket but have not put it on yet because until the aero is better ther is no point yet. I started by making a long skid plate from only 2" behind the front wheel too 2" infront of the rear wheel. This winter I am making aluminium cargo boxes to fit close behind the riders legs and making a front fairing that is better than stock. I believe this type of bike can be made more aero but is not the best choise for that type of project. I still want to ride this bike in the dirt and on the gravel roads. The fuel tank is so small 7.5L that better fuel economy would be real benificial.

Last edited by redyaris; 02-26-2011 at 08:01 PM..
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