Okay, so I'm thinking about CBFryman's comments about how wind resistance is everything, and especially so at highway speeds. The vast majority of miles I'll be putting on my Ninja 250R is going to be at around 60mph. Right now, I'm at 61-63mpg. Can I make it to 100mpg?!? Anyone wanna place bets? Anyone wanna help with aerodynamics advice? I'll be making one mod at least every 1 month or 1000 miles thru autumn. I need to space them far enough apart to get a few fillups on them so I know what each change has done. I'll keep updating this post with new info. Mod 0: (because it's always ongoing): lightweight fasteners. To offset the increased weight from some of the mods, I'll be using Al and Ti fasteners wherever possible. I'll also replace small brackets with parts of my own design. Mod 1: rear fender skirts of my own design. These will help create somewhat of a "teardrop" shape out of the bike's tail area, where before it was just open. Alternative would be fender elim., which does nothing to cover the rear wheel. Tested, and is known good for about 2mpg. Mod 2: HotBodies GP windscreen. The GP windscreen is supposed to be 1" taller than stock (by that, the bubble shape is taller- the windscreen is not actually longer than stock), which should help push air over me, and make it possible to do Mod 2.5, a windscreen extension. Mod 2.5: windscreen extension of my own design. This v-shaped piece of .040" thick aluminum pushes the bolt holes for the windscreen about 3" from their original positions. since the windscreen is mounted diagonally, that's about 2" up and 2" back. I've mounted this on the bike as of 7/20 with my stock windscreen, to see what difference it makes by itself. The new windscreen will go on later this week. Mod 3: front airdam. This piece covers an exposed area of the bottom front of the bike (in front of the exhaust header), where it is now open (see pic below, and yes, I'll be painting it black). This will force some more air around the bike's smooth fairings that would otherwise go into the engine compartment and then under the bike, contributing to turbulence. It also should force slightly more air through the radiator that would otherwise just have blown under it. Mod 4: rear license plate vertical holder: made from lightweight aluminum, instead of heavy stamped steel like the stock piece. Takes up a smaller profile on the rear of the bike. Mod 5: new muffler and carb re-jet: before changing the gear ratio, I wanted to bump up the engine's power and efficiency. The OEM muffler from a '09 Ninja ZX6R is lightweight and made to flow gobs of air, so that's what I used. It's also reasonable attractive and fairly aerodynamic. Mod 6 - 4/2010: front sprocket, 15t (OEM is 14t). Bumping the final drive ratio by changing the front sprocket should put the engine at a slightly more comfortable RPM for better miles per gallon. Increasing sprocket diameter will also mean the chain has to flex slightly less, resulting in a tiny bit less power loss and chain wear. Mod 7 - 6/2010: front fender. after testing, I've decided to stick with the ZX14 fender. MPG is back up to just a hair over 70 now. The ZX14 fender has better coverage than the OEM 250R fender for improved aerodynamics. Mod 8: 39t rear sprocket. Smaller, lighter (aluminum alloy) rear sprocket, w/ 39 teeth vs the OEM 45 tooth version. Final drive ratio is changed even further, putting 5th gear where 6th gear was with just the 15t front and OEM rear sprockets. RPM @ highway cruising speed (62.5mph avg) is 6225. Potential top speed is 125.4mph (although without further power adders and/or aero improvements, I'd never see that kind of speed). With the stock setup, the same RPM would only produce 101.5mph! Mod x: lower the bike about 1" front and rear (RoaringToyz lowering links and handlebar spacers). Nothing "extreme", but just to get out of the air flow a little. The less frontal area, the better. Mod x: airbox removal and aftermarket filter install. Getting consistant reports of increased performance by removing the restrictive OEM airbox. If efficiency is increased, the gear ratio can be further changed by swapping to a smaller rear sprocket. A rejet would be required, which would likely decrease MPG until the gear ratio was adjusted Mod x: larger storage compartment to replace rear seat? This is a "maybe" item, based on the post by c0ldf1ame below. I'd need one of the Kawasaki rear seat cowls for the original mounting points, then I'd have to make a larger shape (from fiberglass or reinforced plastic) that would attach in the same manner. If the shape was an aerodynamic extension of my body on the bike, it would help aerodynamics. I've seen those "hypermiler" bikes with a huge piece on the back, and I ain't doin' that. It would be nice, though, to have a locking compartment big enough for a small bag of groceries, change of clothes, or my lunch box. Mod x: LED/ HID lighting. I recently replaced the tail lamp with LED, mostly because it lights up brighter and faster than an incandescent. This was done in conjunction with a brake light strobe, which automatically flashes my brake light 3 times before staying on solid. Increased saftey = win. Combined with other alternative lights, a drop in electrical load will free up engine power for motive work. Taking advice on what else I can do to get the air to slide around me. Not looking for a big damn race fairing or anything. It still should look (pretty much) like my bike. Mod 1 - rear fender skirts: Windscreen Extension (shown with OEM windscreen): front airdam, slides more air around the body that would wind up in the engine bay (terminates well below the radiator, though, so cooling is still sufficient). vertical license plate mount.