[jpoole]

Originally Posted by derangedhermit

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.

I too have an '09 wr250x and my FE jumped from 62mpg to 72mpg when I started running without the airbox side cover! I had no other changes made and the bike was totally stock. I thought it was just 'cause it was new and breaking in so I put the cover back on and to my surprise the mileage went back down around 62. I went to a 48t rear sprocket for some low end grunt but the mileage dropped to 57ish. I put a 14t up front (with the 48t still on back) which should be a ratio somewhere between stock and where I am now and if it doesn't get much better, I'm going back to the stock 42t rear.