Low & Slow's Ninja 250 project

[sendler]

Truncating the tail a bit may be just as aero according to Kamm and anger the cops a lot less. Do you feel the sidewinds blowing you of line more now with the front wheel fairing?

[Grant-53]

Right about the front wheel disks; they were a disaster on road bikes. All my fairings attach to the frame now. Craig added ballast to the nose fairing to counter lift. Hopefully a different profile can be devised to get some down force instead. Yes, I have the DVD. I also spend time studying sailplane designs.

The Ninja is looking better but don't be ashamed of the Kawasaki green paint- it really shows up well. White with black and red is very visible too. Better seen than hurt!

[low&slow]

Sendler, Funny you should mention the cops, I got pulled over by the CHP on Wed. I knew I wasn't speeding and wondered if he didn't like how my license plate was mounted. He told me it looked like I was weaving around a bit and he wondered if I was having a problem. It was pretty windy and it was moving the bike a bit but nothing of any significance. He asked if there were commercially available panels and I explained there was nothing available like I had made . I explained to him that my body panels are flexible and he was seeing the deflection from the wind. He was very interested in the streamlining and asked me if it was OK to take some pictures of it. He checked my license and registration and then I was back on the road. I really wasn't moving around that much so I'm pretty sure he was just curious. The wind sensitivity is slightly more than stock but not much.
Grant-53, yes it would be preferable to fair in the front wheeel ala dustbin style vs the fully enclosed fender. I'll eventually go that route but for now the benefit outweighs the negative. The lime green paint does stand out pretty well on the black.
Thanks to you both for your input.

[low&slow]

I filled up this afternoon after running some errands and the results are ....
78.47 mpg ( 2.35 gal for 184.4 miles) So close to 80 mpg. The taller gearing is working great, still good acceleration and I think some room to go taller. I have GreenJoe's 33 tooth rear sprocket but I think that might be too much, plus I would have to shorten my chain or get a new one. I may see if about testing Alan's 39T. I need to talk to Craig about getting the 3rd Vetter tail. Things are looking up.

[jkv357]

Sounds like you are on the right track there Vic.

Have you looked at your plugs lately? Because you are dropping your cruise RPMs significantly, you may be able to go to a hotter plug. The stock plug is a balance between low RPM and high RPM operation, and I bet you don't spend much time up top.

Because the majority of your riding is at low RPMs, I bet the stock plug is too cold for maximum efficiency in that range.

Here's a link with info about reading plugs for heat range and mixture - Reading Spark Plugs Correctly


Jay

[low&slow]

Hi Jay, Good idea , I checked them when I first got the bike. I'll check tham again. Thanks for the suggestion and the link.

[jkv357]

You're welcome Vic, good to see your progress.

One other thing that came to mind to increase your efficiency would be to drop down in oil viscosity. If you are running a 40 grade oil you could most likely safely drop to a 30 grade oil for less resistance to flow. Synthetic is always a good idea IMO.

It's possible you could even go to a 20 grade synthetic (if you could find a suitable one). Mobil1 makes racing oils in 30 grade, and even if they do contain friction modifiers (not sure) they do also have good/safe levels of ZDDP, unlike current standard auto oils. It's questionable whether modifiers are a significant problem for cycle clutches IMO, but low levels of ZDDP are a better reason to stay away from auto oils in engines without roller lifters.

Mobil1 oil specs - http://www.mobiloil.com/USA-English/...duct_Guide.pdf

Last page has the Racing oils. For the most part all oils labled "Racing" have high levels of ZDDP that could eventually damage a catalyst if one is used. That's one of the main reasons they are not recommended for street use. Less detergents may also be a factor.


Jay

[greenjoe]

Low&Slow, I really wish you would try the 33t sprocket. I ran it with best results @ 14/33 and averaged high 70's to low 80's mpg with stock bodywork and riding it for all it had. I always just used a cheap non o-ring chain on the 250, about 18 bucks. I don't think the little ninja makes enough power to wear out a chain. I ran the 125 ninja over the weekend and lost close to 10mph with the new gearing, it's way too tall but I'll try to make up for it with a new front fairing (under construction).

[low&slow]

Greenjoe,
I think I will do just that . The more I ride around with the 15/41 gearing and see how easily the Ninja handles it the more I think that the 15/33 combo work. I will need to get a shorter chain first as it is pretty close to the end of the rear axle slots. My current chain has a couple of stiff links and looks like it was not well taken care of.
If you can't reach your previous top speed in top gear , can you go faster in your next shorter gear? I may not be able to go the Ninja's rated top speed ( ~110 mph) with the 15/33 combo but as long I can cruise at 75-80 mph on the flats with it than it will be a keeper.
all the best, L&S

[BHarvey]

Yes, a non-oring chain will work just fine. Once took a friends advice on the non-oring chain and it netted 7 more mph on the the back straight at Road Atlanta.

Much less friction!