Low & Slow's Ninja 250 project
 

After the recent Las Vegas to Barstow Vetter Challenge I have thought a lot about my future participation in these real-world fuel economy contests. While I'm pleased to have improved a 40mpg bike into a 60mpg+ machine I have to recognize the inherent disadvantages my Yamaha Vision ( 550cc shaft-drive bike) presents versus the 250cc gas bikes and the diesel bikes that have been the previous Challenge winners ( 134 mpg to ~ 157 mpg). I decided to start looking for a used 250cc bike to modify for future fuel economy runs.
After about 2 weeks of searching I found a 1999 Kawasaki Ninja 250 in good running condition for a good price and well under my project budget. It was a salvaged bike and so I had to have it inspected and the engine and frame #s verified to get it titled and registered for street usage.
I adjusted the valve clearances, sparkplug gap, cleaned and re-oiled the air filter and changed the oil and filter. I topped off the tank and rode it around running errands for a few days before doing my first official mpg calculation: 65 mpg.
Today I rode with Alan Smith( Ninja 250 streamliner ) and another stock 2008 Ninja 250 as well as a Triumph 1100 and a BMW 1200. We topped off our tanks at the start of ride and refueled at the end of the ride 126.7 miles later. The ride was at a spirited pace on twisty backroads on a cold day with with about 15 freeway miles on the way back. Alan got 89.47 mpg, the 2008 ninja got 62.1 mpg and I got 72.8 mpg. I was pleased with how the bike runs and how well it handles. It was interesting to compare the 2 stock ninjas with Alan's to see how effective his modifications are.
Now that I have my baseline I'm ready to start my modications. I'll start with a larger countershaft sprocket ( 15 tooth vs 14) and larger windscreen. I'm pleased to already have beaten my best tankfill on my Vision 550cc ( 66.8 mpg) . I'll try to keep posting on my progress.
Happy New Year , L&S

Looking good L&S
What you mite also be able to experament with is shrouding and boat tailing behind the rear wheel attached to the swing arm. I suspect you will find some "very interesting results" at this stage of development...

Thanks, a long tail is definitely in the near future as well front and rear wheel shrouding

I don't usually subscribe to threads, but I'm making an exception.

Are you planning a fuel injection set-up?

Kirk

Hi Kirk, No current plans for fuel injection so far but I wouldn't rule it out. I haven't looked into it much yet and the only potential drawback would be the cost. The gearing and aero mods are cheap and very effective so I'll start there.
all the best , L&S

I just looked up sprockets for the EX250 and PBI sprockets has the largest range; fronts are 13 - 18 teeth and the rears go from 33 - 60 teeth. what I am wondering is will the EX250 accept a bigger than 15 tooth front sprocket without having the chain/sprocket contact the case? for the rear going from 39 teeth to 33 teeth is a 15% reduction so 6500 rpm will be reduced to 5500rpm if you can add a 16 tooth to the front then an other 6.6% rpm reduction drops the rpm down to 5150rpm at 70 mph. at this point the full benifit of the aerodynamics will be achieved.

Wow! fast research. From what I've read 16T on the countershaft sprocket needs grinding for clearance. I'll pass this on to Alan.
many thanks L&S

I've "bin dare dun dat" more than once for mini road racing bikes and hare scrambls. PBI Sprockets will also make custom sprokets if a few of you EX250's can arange for a batch lot order. Maybe you's can get down to a 15/30 setup on the ninja 250's, which would drop the rpm down to 5000rpm at 70 mph.

The only problem that may present itself is starting in first gear, specialy on hills. My Suzuki GS 500 [Gray] required a little more careful/gradual clutch engagement when starting out.

It'll be interesting to see how it goes. Considering getting one myself.
I'd recommend some Avon Road Rider tires as they roll very well and have great wet and dry grip.

Report #2 After getting the baseline for the Ninjette ( 72.8mpg ) I could hardly wait til I started doing some mods. I haven't bought sprockets yet so I decided to start modding the front end of the bike. I removed the windscreen and front fender . I made a longer, taller windscreen out of coroplast and mounted it on the stack faring. I made a fully faired front fender out of sheet metal, coroplast and some outdoor sign stock. Since I'm going with a Vetter tail, I just bungeed on a plastic trash receptacle behind me until I start building the tail. I need to do another run see how it works. more to follow.
all the best, L&S

pics please !

as requested !
I ordered a 15 tooth front countershaft sprocket and hopw to receive it soon. I may go with a 39 tooth rear sprocket later. I also replace the seat with one I made for a lower seat height. I rode it yesterday and today and it seemed to dowell in the wind, better than the Vision.

l&s, send me an address some how, and I will send you a 33t rear spocket to try. My best results was with 14/33 and lowered the bike 2inchs{lowering link & clip-ons} no real aero mods. The 15/33 gearing was too steep for these Tennessee hills.

Hi Greenjoe, Thank you for the offer, I'll send you a PM! I think Alan Smith may be running a 33T rear sprocket on his Ninja 250 so this will be a good test .
My bike is going great on the freeways with the modded fender and windscreen. It is just screaming for higher grearing. Currently with stock gearing and a larger rear tire ( 120/80-16") it running 8500 rpm at 70-75 mph. It will be interesting to see what kind of mileage I'm getting with these mods.
all the best L&S

This may be stating the obviouse, but I suspect that until the aero is improved you will hit a limit on sprocket changes improving fuel economy.
I have a Yamaha WR250 that I have a 14T front sprocket for, but have not instaled because the bike can not maintain a reasonable highway speed [100km/h, 60mph] in 6th gear in head winds. So until I can make some aero improvements the 14T sprocket will sit on the shelf.
Keep up the good work, when do you expect to be installing your "Vetter" tail end?

Hi RedYaris, The Ninja feels much improved with just the fender, windscreen ,seat lowering and temporary tail. I'll top it off and evaluate my progress in the next couple of days before I start raising the gearing. The 15t front/33 T rear combo may be too much at this point but we'll find out. Right now the bike pullls top gear down around 35 mph easily so I should have lots of room to bump it up. I probably will start on the Vetter tail right after playing the sprockets. I'm meeting with Alan on Thurs. or Fir. so he can critique my work so far. He and Craig are working on a new front end for his Ninja.
stay safe, L&S

Vic, I'd consider just going straight to the 15/33 gearing. The only real limiting factor here is if first gear is too high. You don't need to be in 6th on the freeway, just use 5th. With a super long 6th you will also be able to evaluate the improvements in aerodynamic slipperyness as it will become easier to pull higher and higher air speeds.

Check out my 101.5mpg Ninja 250 thread. Just gearing mods and riding technique got me there.

http://ecomodder.com/forum/showthrea...50-a-8686.html

I went with a 15/39 setup for a 2.60 final drive ratio. In my experience, anything lower would be detrimental. My bike already slows down considerably on minor upgrades in 6th gear. With a lower final drive you certainly can use 5th gear on the highway, and maybe leave the availability of having an extra low 6th gear to gauge future aero mods. However, i don't think all the aero mods in the world will allow a really low 6th gear to be functional. Hope you prove that wrong!

You can not fit larger than a 15 tooth front sprocket without both removing the sprocket cover and grinding away at the case.

I'd also advise away from attaching a fairing to the front wheel. You'd be much better off extending the stock fairing out over the front wheel.

Hi Garth, My plan was to install the 15T countereshaft sprocket first note the change then install whatever rear sprocket I have handy which will probably be 33T rear that Greenjoe wants to send me. It may be too tall ( low numerical ratio ) or not. I'll find out.

TCMBrian, Great to hear from you! I have read your thread and commend your excellent efforts. Thanks for your input and advice about gearing taller. I'll see what happens with the 15/33 combo and post my results. I posted on your thread and was wondering how things are going this your Ninja. I hope to join you and Alan Smith in the Ninja 100mpg club soon.
all the best, L&S ( Vic )

Hack that Kawi!

L&S, shipped the sprocket today via US Mail, should be there first of next week. Hope it will help in some way, just collecting dust here.

I like that you are willing to help others. Thanks for being you.

Kirk

Thanks GreenJoe! You are the man! I'll do my best to make you proud. I'll let you know when it gets here.
Many thanks L&S

Both of the sprockets arrived in this evening's mail! I need to finish testing the current aero mods and then I'll install both sprockets to see if the little Ninja will pull the 15/33 combination. If not, I'll go with 15/45 for a while. I'll post the test mpg shortly.
Thanks again GreenJoe , you are awesome !!!

Wow, that got there fast, I figured next week. I can't wait to hear the results. I like to go to the extreme gearing first and work my way back up, it's just the way I've always done it. I still like the 14/33 set-up. Your project has modivated me to pull the 125 ninja on the lift today and started on some body mods, so the thanks is to you L&S. Have fun testing, and again, can't wait to hear about it.

Yes , the sprocket got here pretty quick. Many thanks GreenJoe! I'm glad you're going to start work on your Ninzuki.

I filled the tank today and the result was 59.3 mpg. Disappointing. I may do one more fillup to get a better perspective on the aero mods. I added a bit longer tail and some panels over the rear wheel.

Once I get the sprockets on I should see some significant gains. :thumbup:
all the best L& S

I did another test run today before installing the taller gearing and the results are.... 74.6 mpg. So at least some improvement over the stock Ninja configuration with the aero mods. I'm going to install taller gearing and will go with a 15T front/ 41T rear combo for now. After some discussion with Alan Smith I decided to try the 41T rear first before going with the extremely tall 33t sprocket that Greenjoe sent me. I feel very optiimistic as the Ninja feels very short-geared, easily pulling 6 th gear at 35 mph.

I rode the bike today with the 15/41 gearing ( vs 14/45 stock ) today and it is much improved. I can confirm that the rpms are now down to ~6000 at 60 rpm. The bike still accelerates very well and actually it can handle even taller gearing. I'm using Alan Smith's spare rear sprocket right now and he also has a 39 tooth rear he offered to let me use. He is currently running a 37 tooth rear right now. I also have the 33 tooth rear that GreenJoe sent me . I'll run this setup for a bit and test it. I'll post the results shiortly.
all the best L&S

I am very excited to have found this thread and you guys here following Craig Vetter's Challenges. I too have been corresponding with him and his wife about their events and an encouraged to see one coming to the Northwest this year in June. I too am putting a bike together to run in the June Challenge, dunno how far I will get but will certainly be there! Best of luck to you guys, hope to see you all there. Mike :{)

Hi Mike, I'm glad you are enjoying my project and are going to be competing in the 2012 Vetter motorcycle fuel economy challenge. I'll be going to the Northwest event and look forward to meeting you. What kind of bike are you going to run?
I hope to get the Ninja 250 over 100 mpg pretty soon so that I will be more competitive in the 2012 Vetter Challenges. Alan Smith's Ninja 250 is currently undergoing a lot of mods and will very likely surpass his best of 116 mpg.
all the best , L&S

L+S
 

I am working on a Honda rebel with a diesel and a full bodied fairing! :{p

:{)

wow, Mike, sounds very cool. What is the source of the diesel egine? Sounds like it has a lot of potential.
best wishes, L&S

L+S
 

I am getting it through a guy here in the states and he gets them straight out of China from the manufacturer. I have emailed with the manuf. many times already , it looks to be a good one so we'll see. :{)

Given that you said that with the stock final drive gearing 14/45 you were turning 8500rpm at 75mph by my math you would be turning 6800rpm at 60mph so the present 15/41 final drive gearing, drops the rpm to 6000rpm or 12%. :cool:
How is starting out on hills with the new gearing?
Have you notice that your ability to maintain a high speed against hills and headwinds has been deminished in 6th gear?

Gearing Commander
 

The Gearing Commander web site has data for most bikes so you can see what speed/ rpm changes result from changing gears.
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Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator

Hi RedYaris, I haven't tested in real steep hills yet but I suspect it's fine. With the stock gearing 1st gear was almost unneeded. The bike still accelerates very well and I think I can go taller as the bike pulls well at ~5000 rpm. I'm sure I will need to downshift more frequently going uphill or accelerating out of turns than before as I was running around in 6th gear almost all the time.
Sendler, Thanks for the link! This will help a lot in looking at the feasibility of taller gearing without physically swapping gears.
Looking at the ratios : 45/14=3.21 vs 41/15=2.73 2.73/3.21 = 85% , so a 15% reduction of rpm currently. Pretty large but I think I can go higher. I can hardly wait to test this gearing out some more and get some results. Its raining very hard right now so to be continued....
best wishes, L&S

yea this is a great project. I am aslo working on a heavly streamlined Kaw250. I think alot of others are on the same path. please keep reporting your results, your doing a great service to this little community.

Hi Electictracer, Thank you! I'm glad to help others as I have helped by others here. This a great forum full of very smart and accomplished people who also are very generous in sharing their knowledge and experience.

Do you have an electric vehicle or an eclectic one? :D Are you going to ride in the Northwest Vetter Challenge on 6/1/2012?

Still raining here so further testing is postponed for a few more days. I talked with Alan Smith about the gearing and he has 39 and 37 tooth sprockets to try out.
Sendler, I used the GearCommander to check the effect the 33T rear would have and appears it may be feasible ( 6500@70 mph) , particularly if I can reduce the aero drag enough to allow decent acceleration.
best wishes L&S

Must be you didn't go to 15 on the front yet? Do they make as small as 33 for the rear? At some point you will run out of room.

Ive done a bit of work with electric bikes, but nothing really road worthy. My current project is a one seat tracer like vehicle with a ninja 250r donor. I just started building and I'm documenting progress on the forum. I would like to go electric some day if prices go down.

As for the challenge, I wont have a working vehicle by then, but might ride my buell up there to check it out if its not to far away in Washington.