Chap 51: Streamlining a Ninja 250

Dec 14, 2011: Building a streamlined nose for a Ninja 250

Alan sitting in feet forward position, holding imaginary handlebars
Alan Smith is the perfect person to help streamline. He rides his Ninja 250 everywhere. He keeps records, too which means he knows the effects of any changes.

I knew he was serious about fuel economy when showed up at the Quail Event this summer with his own streamlining. He 4th place and beat me on my sreamlined Helix. Then he rode that same 250 to Virginia and back on the way, stopping at the AMA Vintage Days Challenge, taking 4th place (and beating me again) before riding it back to California.

You can see how we built a real Vetter Streamlined Tail for his little Ninja In Chapters 44 thru 49. Now he can carry four bags of gorceries without any arguements. Alan could be a real contender.

It is time to finish the streamlining by adding the Vetter streamlined nose. It became clear that we needed a second Ninja to play with. Besides being possibly the best gas motor bike to streamline for a Vetter Fuel Economy Challenge, used Kawasaki Ninja 250s loose their value when dropped. We can afford to experiment with the little Ninjas. Alan found this one on Craigs List:

It is much easier to build mounting brackets on an empty frame.

Alan is very happy with his 1998- 2007 series Ninja 250. Actually, I know of four Challenge bikes being built on Ninja 250 based streamliners. We will finish the streamlining on Alan's stock-framed Ninja and get a year's worth of riding results. At the same time, we will convert the above frame to lower the rider's seating position. This will give the rider more comfort, reduce frontal area and further improve streamlining. Adding a nose to a stock framed Ninja is step one. Step two is to modify the Ninja 250 frame to produce the configuration below:

The future: A stretched and lowered Ninja 250 (step 2)

Step 1: Generating the streamlined nose for a stock framed Ninja:
Checking the Helix prototype nose for fit:

To the left is the nose structure that I made back in Chapter 43 to check shape and fit. My best guess was to make it of .125" and .100" aluminum. It became obvious that I could make it of much thinner and lighter materials.

This first nose way too wide... 28". The tail is 24" wide. We want to bore the smallest hole thru the air possible. I decided upon 25" as being the best max width for the new nose.

New 25" wide nose model:

The revised dimensions meant that I had to make an entirely new nose mockup in plywood and wrap it with milk carton paper.

New nose fitup:

Alan props the new nose mockup in front of his Ninja

New nose aluminum bulkhead parts:

Alan marks the line that will make the rings and makes the parts from aluminum. For simplicity, I made this bulkhead symetrical which means all four of these pieces are the same.
These are all the pieces needed to make the nose. It is critical that they be cut out accurately. The bulkheads Alan is pointing to are .100" aluminum. The bands are .032" alum. which simply form around the bulkhead perfectly.
Alan drills for flush mount Pop Rivits and assembles the nose. Each little angle bracket has a different angle. Taking the time to make sure each was at the perfect angle made assembly easy. Alan and I are learning these little tricks so we can pass them on to you when you make your streamliner kit.

Before we put the aluminum skin on, we propped the nose structure on the bike to see what we have:

I check to see how the nose curve will fit over the bigger Ninja front wheel. It looks fine. Alan pretends he is cruising with his feet on the pegs, holding his hands in a comfortable position. We will have to make new handlebars for this new riding position. Alan thinks it feels fine, too.

The nose is being designed to be arttatched with three fasteners, just like the tail. Alan has made his bracket attach to the existing Ninja fairing mount. A quick wrap in temporary milk carton paper begins to give us an idea of the size of the streamlining.

A variety of riding positions

Alan is mocking up the new handlebars. They must be about 6" higher and farther back. Alan wants to be able to sit comfortably and also be able to move about to stay comfortable. After all, this is to be a serious cross-country machine.

The main mount for the nose is a very strong crossbar. It will be used for the forward controls as well as providing a feet-forward sitting style.

In determining the nose shape, I wanted to confirm that the nose was wide enough for the bars to be turned full lock. This is the time to be catching any problems.
Next: I have fired up the designers' clay to begin making the nose.

Master Index to the Last Vetter Fairing Story

Posted Dec 15, 2011

Updated Dec 28, 2011