Low & Slow's Ninja 250 project

[MPG_Plus]

I have a 2008 Ninja 250 and put a 16T sprocket on the front with a minor clearance mod to the chain cover on the inside that doesn't show, and no changes to the engine case with plenty of room. I also put a Scott-oiler on but have not switched to a non-Oring chain yet. I am averaging about 85 MPG (3 tanks)with a peak of 100 MPG. I am sure the peak was due to where it was topped of with a small tank. The rear sprocket is now a 38T and accelerates just fine. I have been thinking about taller gearing and a non-Oring but it seems I might need some aero mods. I also added a rear view camera which I really like for safety because the stock mirrors have poor visibility when tucked.

[jkv357]

Originally Posted by MPG_Plus

I have a 2008 Ninja 250 and put a 16T sprocket on the front with a minor clearance mod to the chain cover on the inside that doesn't show, and no changes to the engine case with plenty of room. I also put a Scott-oiler on but have not switched to a non-Oring chain yet. I am averaging about 85 MPG (3 tanks)with a peak of 100 MPG. I am sure the peak was due to where it was topped of with a small tank. The rear sprocket is now a 38T and accelerates just fine. I have been thinking about taller gearing and a non-Oring but it seems I might need some aero mods. I also added a rear view camera which I really like for safety because the stock mirrors have poor visibility when tucked.

Welcome aboard!

How do you like the rear camera? What brand is it? Was it a model made for the Ninja, or did you adapt something else?


Jay

[cosmic_kid]

I've been in love with the Ninja 250 for a lonng time, but now that the CBR250r is out I'm torn. The CBR seems to have more eco-headroom, since it's fuel-injected, but there is so much data, and parts, out there for the Ninja, it's hard to overlook. On top of that the price difference between a CBR vs. a Ninja would buy quite a few tanks of gas in itself... Any suggestions? BTW, this would be my first motorcycle, beyond playing around on a dirt-bike in the yard.

Thanks,
Will

[jkv357]

Originally Posted by cosmic_kid

I've been in love with the Ninja 250 for a lonng time, but now that the CBR250r is out I'm torn. The CBR seems to have more eco-headroom, since it's fuel-injected, but there is so much data, and parts, out there for the Ninja, it's hard to overlook. On top of that the price difference between a CBR vs. a Ninja would buy quite a few tanks of gas in itself... Any suggestions? BTW, this would be my first motorcycle, beyond playing around on a dirt-bike in the yard.

Thanks,
Will

If mileage is your goal, the CBR will win every time.

But for your first bike I'd look for an older Ninja. It will do exceptionally well also. All of the "mods" available for the Ninja are meant to increase peak power, and do so mostly at the expense of low and mid-range, so stock is going to be hard to beat for mileage and around-town riding.

Because this is your first bike, I wouldn't get too hung-up on what's "best". You can find an older Ninja for cheap and learn a lot by doing the maintenance and tuning. Insurance will be significantly less for an older model as well.

Never finance or buy a new motorcycle for your first IMO. Make sure you have money left for a complete set of quality gear.

Take a MSF (or similar) riding course before hitting the streets.


Jay

[beatr911]

Good first bike advice from jkv357. You can always buy a depreciated CBR250R later.

[low&slow]

[QUOTE=beatr911;291601]Great numbers!
A couple of questions to get some perspective though:

1) What would you say are your average speeds for the 90mpg tank?

2) What is the engine speed at say 70 mph?

3) What is the hp produced at say 70 mph?

4) How did you verify the accuracy of your odometer?




Hi Garth,
1) The 90 mpg tankfill was mixed riding with an even mix of freeway, city road and backroad. Average speed was probably around 45-50 mph. Freeway cruising speed was about 65 mph.
2) Engine speed is about 4500 rpm @ 70 mph in 6th gear with the 15/33 gearing. I'll have to check and confirm this.
3) According to the only dyno chart I have for the EX250 the HP would be about 8.5 Hp @4500 rpm.
4) I did a Mapquest round trip to my destination ( my house to the Livermore Junction): 75.46 miles. I noted the mileage on my odometer and tripmeter at the start, midpoint and the return trip ( 69.1 miles). 75.46- 69.1 = 6.3 miles undereported. 75.46/69.1 = 1.092 correction or 9.2 % under reporting.

Thanks for the advice on the iridium plugs and increasing the gap. I rode some yesterday is very windy conditions and found it hard to stay in 6th gear when going into the wind. I ended up cruising in the 5th and 4 th gear much of the time. The taller gearing has magnified poor part throttle response; I need to clean, check and adjust my carbs to hopefully correct this.

[sendler]

Looks like 15/ 33 gearing should result in about 5,800 rpm at 69 mph for a pre gen Ninja with stock tires according to gearing commander. The aggressive cam tuning of the Ninja has no power to pull below 4,800 so you may end up using 4th and 5th more often where 6th will be an overdrive.

[jdchmiel]

do aftermarket cam / cam gear(s) exist?

[beatr911]

Sendler, Thats interesting! The CBR makes more hp and torque at 5800 theoretically able to enjoy even taller gearing than the Ninja. Gotta love thumpers.

Vic, believe me I know 14hp isn't much. But my 200 makes ONLY 14 hp with no more on the downshift. I can't do 70 though except down a small grade.

For the plugs you can tune them to get the max effect by opening up the gap in .005" increments until you start losing power at max output. Then close by .005" and your gap is dialed in, whatever the plug you are using. This will not provide a margin for plug wear so they will require more frequent re-gapping though.

Your mid range mixture is controlled by the needle in the slide. Shimming the needles up with tiny washers is a common fix for lean mid range since you probably don't have an adjustable clip for the needle. Due to the age of the bike it's a good idea to do the cleaning, but inspect/adjust the float levels with accuracy as well as the sealing of the boots and mount to the head. Kawis of this era tend to have fat main jets, you'll need to use an O2 sensor and gauge to dial that in correctly though. Don't guess.

[sendler]

Originally Posted by jdchmiel

do aftermarket cam / cam gear(s) exist?

Not for fuel economy but if enough of us start using the Ninja for hypermiling we might be able to get something custom ground. If the gears are slip fit, it might be possible to detune the stock cam timing somewhat. I'm not crazy about carbs any more either but it is hard to argue with the thousands of good used Ninjas out there.