Buying a bike for MPG/Vetter Challenge, what would be your favorite?

[beatr911]

Vic, congratulations. That's a great price for a complete Ninja 250. Please start a build thread so we can follow your progress.

-Garth

[beatr911]

Old Mechanic, Thanks for the info on the CBR250R. I'll be selling off the old stock and looking for a salvage CBR. I love the fact the rear section is just bolted on, should make an Alligator mod much easier. I suppose someone will come up with a hack to correct the speedo for gearing changes as well as be able to change some other FI behaviors to maximize mpg, just may have to wait for a while.

What changes have you noticed after the 3000 miles?

[user removed]

Maybe I did not explain it properly. The rear mono shock is almost directly under the back of the fuel tank where the frame is triangulated and probably the strongest part of the frame. The rear portion of the frame is not bolted on. There are two tubes that extend back and support the seats and the rear fender, lights, etc. You could easily cut off the rear tubular section and make a lower seat position, but would probably have to relocate the air filter housing or make a different one. The rear wheel has a small plastic fender that is very close to the tire and moves with the suspension. Since all of the rear axle loads and stresses are directed to the pivot point of the rear suspension and the mono shock, nothing behind those two locations really is important.

Find one with the back damaged or one that was down and you would have the basis for your streamliner.

regards
Mech

[low&slow]

Thanks Garth!! I got the bike home and it runs pretty well. The tires are even pretty good on it. I need to get it registered and serviced and then I'll run a tank or 2 as a baseline. I'm thinking I'll change some sprockets first before I start working on my aeromods. Good luck with your search for your project bike ( also to Old Mechanic ).
all the best, Vic

[jkv357]

Congrats Vic! It will be interesting to see what your baseline number are.

If you are looking for some Ninja 250 info, check out - Ninja250 Riders Club :: Index

Post up some more shots of it when you can.


Jay

[FXSTi]

I'm broke right now but thought one of you could use this 1988 kawasaki ninja 250

It is in the Lansing Michigan area.

Good luck
Kirk

[Michael Moore]

Vic, before you rush out and buy sprockets consider going to a smaller chain size from stock.

The 250 Production folks who race EX250s have found that going from the stock size to a 415 or 428 chain and sprocket makes a noticeable (about .5-3/4hp IIRC) change on a Dynojet acceleration-type dyno. Obviously, the difference is not from an actual horsepower increase, but rather that the parts spin up quicker which the Dynojet sees as more power.

So you'd get both a bit better acceleration and a small reduction in weight, some of it unsprung. For the type of use you'll be giving it there shouldn't be significant longevity issues from the smaller chain/sprockets.

cheers,
Michael

[low&slow]

Hi Michael, Thanks for the suggestion. I just got my Ninjette titled and will be doing a baseline run. Then I'll start modifying it to achieve optimal fuel economy under "Vetter conditions". Do you have a motorcycle currently?
Merry Xmas , Vic

[Michael Moore]

Yes, but I'm at a current low for the past few decades of about 8-10 of them.

I had an EX250 on the street for a bit before I turned it into an AFM 250 Superbike racer (the original plan was to build a custom framed one for the F3 (125 GP) class.

Euro Spares - The EX250 + 125GP = ? article

If you think it would be of any use to you I've got a Specialist II race exhaust system for a Vision (I think you've mentioned having one of those) that was on a friend's racer for 4 or 5 races in the 1990s. It isn't doing me any good sitting in storage and it is yours if you think you want to mess with it.

Any aftermarket exhaust for an EX250 I've seen has generally been 2 into 1s with large headpipes and minimal silencing, so I'd recommend you stick with the stock exhaust to start.

I've always been a racer and fuel economy hasn't been a significant concern (I deal with economy by driving on the street as little as possible) but I am interested in extracting power efficiently and not throwing it away with bad aerodynamics. I've got an FF project among all the vintage dirt bike/roadracers/piles of "there's a bike in there somewhere" stuff.

cheers,
Michael

[Ken Fry]

Originally Posted by beatr911

For big-effort, maybe the optimum current bike would be a modified, lightly crash damaged CBR250R made into an Alligator wannabe, then streamlined? Not exactly easy but should produce an easy 120+ mpg under the Vetter conditions. Brushing up on aluminum welding skills would be a good idea for the frame and swing arm changes.

I think the CBR would be very hard to beat. Closed loop fuel injection is essential, so one might as well start with something with all the pieces matched to begin with. Other things being equal, I'd expect a single be slightly more efficient (in BSFC terms) than twin.