Improving Aerodynamics on a Ninja 500R [ Archive] - GasSavers.org - Helping You Save at the Pump

This summer I purchased an 99 Ninja 500r. The drivetrain is great, the fairings are Fair. This is the perfect candidate for trying to improve the Cd of a bike. The 500 is about the right cross of power/efficiency for my driving. I spend a lot of time on the interstate on my 35mile commute, so I need the extra little push just to get around traffic sometimes (I don't want a smaller bike). The body is fair (upper fairing broken already) so as long as I am going to be fixing it, I might as well try to do it "right".

http://www.totalmotorcycle.com/photos/2002models/2002-Kawasaki-Ninja500Ra.jpg

So far, I have been able to get 64mpg out of it, but I think as I refine my driving a little more, I can hit 70mpg.

Now, the question is, how can I do better than that.

I have come up with 2 options from a lot of thinking and searching online (including threads here).

1) Find a better, more aerodynamic front fairing from a newer bike and make it fit. Modify it to be more aerodynamic (like removing unneeded air vents, etc). Create a front fender that covers much more of the front tire.

This would be reasonably cheap and if done right could make the bike look a lot better than now. I am thinking something sorta like the front of this.

http://motobody.com/newimages/gallery/joedalybuell.jpg

2) Buy a dustbin fairing and make it fit. This has a lot more potential for aerodynamics, and would be a lot more unique. The biggest downfall would be cost (575 + shipping for one like below) and the potential increase in crosswind issues. I would also have to come up with a headlight assembly (and turn signals, mirrors, etc). The front fairing below is currently available new.

http://motobody.com/newimages/gallery/Polkabladustbin.jpg

My goal would be to break 100mpg, be very drivable (no full enclosure) and have a top speed of faster than I care to go. So far, I have the last 2, but I would love to get the first one.

Has anyone else done anything like this? I have looked at Vetters stuff, but I don't have any interested in a scooter (I spend way to much time on the interstate). I have seen the 300/400mpg bikes from the early 80s also. Interesting, and something to loosely model after.

Any opinions? Anyone know of an sites that have good info on this? I would love to get some feedback from others who are economy minded and have a grasp on aerodynamics (I have recently discovered gassavers and ecomodder and am REALLY exited be here, what a great resource of info).

-Mr_C

Most production fairings are build for specific styling cues rather than aerodynamics.

Buell on their race bike recently did try to get it better.
http://www.diseno-art.com/images/Buell_XBRR.jpg

In the late 80's it was common to remove the lower fairings as they would drag and there was the thought that they did more to catch wind rather than smooth it out.
http://www.backroadsboogie.com/images/gsxr1100_1.jpg
It would be easy to remove the lower and see what you came up with on some testing.

Mirror removal, turn signal removal, bar end weight removal all could be done also to get some things out of the wind.

Thanks for the tips on the Buell, I found some aftermarket suppliers for a Buell GP fairing that is pretty cool.

As far as your other tips. I currently don't have front turn signals due to the previous damage, and the rear ones don't stick out very far. I do have rear view mirrors, but I really like them. I might try just folding them back and doing some coast down tests. I would have to find soemthing more aerodynamic to replace them. I hadn't thought of taking of the bar ends either.

You also mentioned removing the lower fairing. I hadn't really considered that. I took a look at it closer tonight and see what you are talking about. its only 4 bolts, so I took it off. it is really easy to see the difference it could make. There is a lot of room for improvement there.

Before-

http://i49.photobucket.com/albums/f263/riveroakranch/ninja/IMG_1483.jpg

After-

http://i49.photobucket.com/albums/f263/riveroakranch/ninja/IMG_1485.jpg

-Mr_C

You'll probably get better fuel efficiency by simply hugging the fuel tank while you ride.. that sure cost little to your wallet when compared to adding a large fairing.

I agree, the most important way to improve aerodynamics on these bikes is to tuck behind the fairing. I always tuck as low as I can go (touching the tank). The fairing changes I am looking at won't make a bigger area for me to hide behind so I will still have to tuck, but they will lower the drag on the front of the bike (and increase my mileage).

-Mr_C

Here's a picture of myself cruising on the highway, I had a comfortable tankbag that I could lay myself against, relief myself of arms, wrists, shoulders, neck.. even my forehead was resting agains the windshield.
I guess it was not very busy traffic, since I was stationary enough to let the rider next to me pull out his camera and take a picture of me at 80+ mph.

http://img.photobucket.com/albums/v237/cat0020/Motorcycling/RS_at_speed.jpg

Here's what I do on my VFR:

http://www.vfrdiscussion.com/forum/uploads/1126144941/gallery_2959_90_386886.jpg

Wow, cat0020, I had never considered riding with my feet hanging on the rear pegs. I gave it a try on the ride home last night (and coming in this morning) and it will defanately take some getting used to. Plus, having the right thickness of support on the tank is important. It was a lot more comfortable than my normal tuck for long rides though (but I generally don't do long rides).

Here's me how I normally tuck (sorry, no action pics, but center stands are convinient)

http://i49.photobucket.com/albums/f263/riveroakranch/ninja/IMG_1511.jpg

Here is your method. I am not sure there is a lot of advantages aerodynamically, but for comfort and just a change in positions, its good.

http://i49.photobucket.com/albums/f263/riveroakranch/ninja/IMG_1512.jpg


-Mr_C

I spent a short amount of time and used "paint" to put a dustbin on my bike. It actually looks a lot better than I expected, just think if it was painted (or photoshopped) to match.

I havent' contacted the manufacturer to see if the dimensions will fit my bike, but I am starting to like this idea more and more all the time. I did move the handle bars closer to where they would be if I were to switch to clipons (which for tucking, would be really nice).

http://i49.photobucket.com/albums/f263/riveroakranch/ninja/DustbinNinja.jpg

-Mr_C

A fairing like that is likely going to cost you more than your bike.

Try looking for a tankbag that is secure enough for you to lean against while you're tucked.. that should allow you to relief some back/arm muscles. I've used Touratech Enduro tankbag on more than 8 of my previous bikes, I've got a few spares if you're interested.

http://www.touratech-usa.com/shop/show.lasso?sku=055-1068&-session=touratech:9B5E3EDE13a7c18DBALSr3500F38

http://www.touratech-usa.com/shop/media2/01-055-1068-02.jpg

Thanks for the advice on the tank bag. I have not purchased one yet mostly because I haven't researched what is best (this is the first sport bike I have had, previously I have just strapped stuff to a rack). I would be interested in a used one if you want to PM me.

As far as the cost of the fairing, it is $575 + shipping. That is unpainted, and I still need to get headlight, turnsignals and mirrors on it, but I like doing that kind of work. I paid $1600 for the bike, so I should be able to keep the fairing cost well under that. Plus, my fairing is already pretty damaged (the entire side of the upper fairing is gone on the side I don't take pics of) so I will be paying some money to fix that anyway... thats why I am tempted to go this route.

-Mr_C

I would not be surprised if shipping for the fairing is in the triple digit.

You might need to rethink the cooling system once that fairing is on, radiator airflow will be significantly reduced. Those exhaust headers will need some airflow to them as well.. they might get pretty hot between your legs without proper airflow.

Magnetic tankbags tend to slide around on the tank, not secure enough to lean against, PM me if you are interested in the tankbag.

yah, shipping won't be cheap, expecially since they are on the west coast and I am in the midwest.

Cooling will definately be an issue, although I think that with the opening for the front tire there will be a considerable amount of air coming through, but it might need to be directed to the right area. I need to get a hold of the manufacturer to see what the bottom side of it looks like, and to talk to them about other people who have tried something similar. Unfortunately they don't like email and I have a tricky time calling durring business hours. My bike does have an electric fan on it, which I have never heard come on yet, although living in MN and it never gets all that hot here.

Aerodynamically, you'd really want to keep you feet in the rider position. There are cut outs developed in the tank and in the chassis for that purpose. With your knees in that position, the air flow is going to be like a tear drop. As you move your feet to the passenger peg position, one's knees now represent a separation of the air flow.

The dustbin fairings of the era were made generally out of aluminum.

Cooling will be an issue.

A fairing more like the XR750 would be more available and easier to mount while still allowing for air flow through your radiator. Just cut back the fairing to allow for your knees to fit into the cutouts.
http://lh3.ggpht.com/_h5sxaV2iMA4/RzH8sx067-I/AAAAAAAAB4Q/cFWc138NOeU/IMGP1209.JPG

Here's a neat example from Erik Buell, a former H-D employee, when he was developing his bike, a 750cc two stroke race bike. Used a lot of cues from the XR750 aerodynamics, but also incorporated a very specific cut out area also to put the tail and the front fairing together.
http://www.motorcyclespecs.co.za/Gallery/Buell%20RW%20750-02.jpg

Mr_C, i have the same bike mine is a 1995 the same color. I dont have the lower fairing on. My gas log shows 48mpg but i was having major carb problems. My bike only has 1100 miles and i just got the carbs worked out, so my next entry should show an improvement.

Now for aero i also tuck and use the rear pegs. I cant tuck as much due to a back injury.

I havent checked yet but for many other sport bikes they make a euro windshield that has a lip that directs the air higher making it hit you further up on your body and making it easer to tuck behind.

I have run 2 tanks of gas through my bike without the lower fairing and have not seen any measurable improvement. I think I am going to put it back on to complete the A-B-A testing to confirm my thoughs. I would like to do another tank or two, but being that it is now the end of august, my warm weather is going to be comming to an end soon, so I want to get a few tanks in with the fairing on to test the mileage before it tanks due to cold weather.

I am a little dissapointed because I have had a hard time beating the 62-63mpg range on the bike, and I thought that the fresh synthetic oil and removing the fairing, along with careful driving and consistant tucking would get me over 65... but I guess that didn't cut it. Time to look closer at changing the gearing and getting better fairings on the bike.


Tepco, could you post when you get your next fillup? I am currious to see what you can get.

-Mr_C

If you've got more than enough accleration and the top speed is way more than you'd ever need, then definately look into increasing the size of your rear sprocket a bit and maybe decreasing the front one too so you can use a similar sized chain.

You can try bar ends too, on my 600R (looks exactly the same as yours but 20 years older) they were just a large phillips. They probably only stuck out 1/2"-1" or so but removing them makes the steering lighter and the bike feel more nimble.

I haven't tried it since my 600R is down for the count, but I had thought of raising tire pressure a bit. You could also maybe trip the foam of the seat down 1-2" which might help you tuck a bit better.

As for the after market front screen that directs air up more, I would be curious if that helps or just increases drag. You could also look into making that 'hump' on the rear seat, not sure where those come from in the aero bike pics, but remember that rejoining your air smoothly is just as important as seperating it smoothly.

As for lower fairing I never noticed any improvements to removing it except it did help keep my bike and headers cooler. In stop and go having that lower fairing on force the electric fan to be used and the headers still got too hot in that enclosed space.

I think the big things you should tri is a larger front wheel fender, remove the lower fairing and move the radiator down a foot or so (but not too close to the header obviously) and then fabricate or buy something to close around where the radiator used to be and the big part of the exposed engine below the tank. I'm not sure what to use though. There was one aftermarket fairing (which was pricey as I recall) that was on solid piece side to side and I think covered the area I was talking about really well. I think it's called AirVortex or something similar.

If you've got more than enough accleration and the top speed is way more than you'd ever need, then definately look into increasing the size of your rear sprocket a bit and maybe decreasing the front one too so you can use a similar sized chain.

Large rear sprocket and smaller front sprocket will raise the engine rpm at high speed.... that would require more fuel. Should be the opposite, smaller rear sprocket and larger front sprocket..

Keep the sprocket tooth and number of chain links as prime number.. i.e. 13 or 17 tooth front sprocket, 29, 31 or 37 tooth rear sprocket, and 113 link chain.. I heard that would increase your chain/sprocket lifespan, who knows?

I have a video from Steve Vetter (yes that Vetter) and this video highlights his fuel milage challenge. bikes had to meet dot rules and be capable of 65mph but other than that it was an open rulebook. This challenge resulted in an 80cc honda capable of 100mph reaching an unbelievable 447mpg. it might be worth a look.

I would imagine that removing your mirrors on that Ninja would probably have more effect on fuel efficiency than removing the lower bellypan... that and inflate your tires up to 38 psi. see how she rides...

cat0020:
I agree that removing the mirrors would have a greater affect than the belly pan (Especially since I haven't seen any improvement from removing the bellypan) BUT, the mirrors serve a pretty important purpose and since it is a daily driver, I kind of enjoy having them... the lower fairing, on the other hand, I don't even notice if it is there or not. Are there any other more effective mirrors that are more aerodynamic? I am not super excited about the ones I have. I seem to spend most of my time trying to see around my shoulders. I have a curved mirror, I should play with putting that behind the fairing and see if I can get that to work. (thanks for the Idea).

I currently run my tires at 42psi (max on the sidewalls) and it seems to ride pretty good. I was having some issues with them leaking, and I don't notice much drivign difference until it gets down to about 20, then it feels a little squishy sometimes. BTW, riding on them at 20 was not intentional.

philip1:
I have spent a bit of time looking at vetters stuff (but I haven't seen his video). That is the model I attracted to, except not so extreme. If I could put some gears and a dustbin on my bike and get it up around 100-125mpg that would rock. I still would have a bike that was plenty fast and drivable, and get good enough mileage that I would only burn through about a gallon to 1.5 gallons a week with my daily commute.

itjstagame:
I agree that the gearing needs to be done. It is just hard because the bike has only about 1500-2000 miles on a new chain/sprocket, so I have been waiting to get a little wear on them before replacing them. I would like to find a nice front fender that covers much more of the tire, but I haven't seen anything that would fit well, and haven't figured out how to make somethign that will be rigid enough and have nice tight tollerances. Plus, if I put a dust bin on it, I won't need a front fender.

I have seen a few sites that claim that the lip on the fairing does little more than increase wind resistance, and doesn't significantly increase the air bubble behind it. It would be nice to see some scientific data to prove/disprove that.



Thanks for the insight guys, it really helps.

-Mr_C