The Search for Fuel Economy

Pages from a Designers' Notebook

Freedom Machine
The goal: 100 mpg at 70 mph, into a 30 mph headwind, with four bags of groceries.
Chap. 33: New gears for the Helix

(The impossible just got possible)

This is what the Helix final drive looks like
Jan Vos of Belgium is well known in fuel economy circles as the machinist who made a new gear set for his Burgman to slow his engine down. He presented his work on ecomodder .

My Helix Streamliner project is stalled out because I need new gears. I don't know how to make them because I am not a machinist.

You can imagine my delight a couple of weeks ago when I received this E mail:

What a gear cutter looks like
Hallo Craig.

I still follow your progess with the Honda Helix. The looks getter better with latest modifications.I think you need for improvement of the MPG a higher gear ratio at least 20% higher than you are using now.I am willing to make that for you against a cost that you cannot refuge.I made a big jump in MPG with my Suzuki Burgman when using the new ratio.It will be spur gears, that is the only type I can make.What do you think?


Jan Vos
What did I think? "Its a miracle" is what I thought! Just how many people are there in world who can and are willing to do this? Jan and I exchanged E mails. All I had to do was send him a set of gears from a Helix and he would do the rest.

I knew where there was a set of gears.

My old friend, Ernie Buckler in Spokane, Washington is an eclectic fan of FF (feet forward) machines. He once mentioned that he had a spare trashed Helix engine. But the drive train was good.

He offered to send it to Belgium. It got there in 3 days! As I post this page, Jan is cutting new gears to slow my Helix engine down 20%.

Feb 19, 2010: Jan is making gears faster than I can put them up on my web page!


As of Feb 19, 2010
Feb 24, 2010

I received the gears today from the wire EDM shop. End of this week the gears go to a shop for hardening. Typically this takes a week and a half. When they are back they can be finished in one day.

Sharp readers will observe that Jan has made two primary output gears, a 34 and a 35. I don't know why. Not only that... I wondered how two different diameters could mesh together. He said either one would work and explained:

"It looks like you are suprised by the possibility of using both 34 and 35 teeth gear with the 16 teeth of the input shaft. I use the possibility of so-called positive correction on the tooth shape to match the clearance . This is only possible with official teeth cut machines. So not more noise for the 34 gear."

Regards, Jan

March 11, 2010... The new gears are here!

Carol is so excited! Thank you, Jan. Now I must finish up the Alcan Fairing on my KLR so I have something to ride when I take my Helix apart. Then I can swap out Jan's new gears and we will all see what happens. These new gears are designed to slow the Helix engine down by 20%. Since they are "straight-cut" we can expect them to be noisier.

March 31, 2010... Time to install the new gears

I am always shocked when I remove the streamlining exposing the little Helix powerplant underneath. There is nothing there! Over the years of development, I have made removal of the streamlining easy... 5 screws. Access to everything is easy. Not so the way Honda made it.

A couple of weeks ago, the Helix did not fire. No spark. I ordered a new starter/stop switch and installed it with the body off. It was harder to install than Jan's gears. But when I pushed the button, it started right up.

Swapping the gears was a whole lot easier than I had expected. Small parts dog, Willie, looks on
I chose Jan's most radical gear... the 34 tooth one. It will slow the engine down the most. I have great confidence in what my Helix can do, streamlined. Next step... button it back up and go for a ride. Stay tuned.

Well, it may not be today. The Helix does not fire again. I took it to my friend, Randy. He can make anything run. (He helped raise out two boys, too.)

The problem was "no spark." The problem was intermittent. Randy soon discovered we needed a new Pulse Generator. When it arrived, it started right up.


But just before replacing the streamlining, I checked again to make sure it started. It did not. Back to Doctor Randy who now diagnosed that the Ignition Control Module had failed. More waiting.

Dr. Randy and bad pulse generator
Many have suggested that I may have caused the problem by overloading the electrical capacity of the little Helix with the Prius headlights. Good thinking but, that was not an issue. Only one of the Prius lights is hooked up and it has the same 60/55 watt halogen bulb that was in the Helix scooter.

Finally, April 25, 2010, we were ready for a test ride. Just in case there were more ignition issues, I decided to do a shorter, 130 mile round trip from Carmel to King City. Same Highway 101... same awful winds. You will be stunned at the results. Click to Chapter 34

Page posted Feb 17, 2010

Updated April 25, 2010

Chap. 3: Road Testing the Long Tail Mar 28, 08
Chap. 1: Streamlining Saves Fuel Feb 20, 08
Chap.2: CAD Streamlined Body Mar 8, 08
Chap. 4: Planking with Foam Apl. 5, 09
Chap. 5: More Wind Testing Apl. 7, 08
Chap. 6: The Final Shape Apl. 17, 08
Chap. 7: Decisions about Details May 10, 08
Page 8: Making the Center Bulkhead June 1, 08
Chap. 9: Rear Bulkhead and Truck bed June 8, 08
Chap. 10: Finish Rear and go for ride June 17, 08

If you have not yet watched my DVD, How they Got 470 mpg it is time to get it for the basic foundation for what we are doing here

Chap. 11: Finish the Tail June 29, 08
Chap. 12: Heading for Ohio, July 13-23, 08
Introduction to Fuel Economy
Chap. 13: Riding in the Midwest July 24, 08
Chap. 14: Vintage Days Ohio, July 25-7, 08
Chap. 15: Summary to date Aug 12, 08
Chap. 16: Adding Weight to the Front Sep. 1, 08
Chap. 17: Truth and Motorcycle Design Sep 4, 08
Chap. 18: Where should the weight be? Sep 25, 08
Chapter 19: Finishing the Streamlining Oct 14, 08
Chapter 20: Streamlining the Handlebars Nov 4, 08
Chapter 21: Unexpected Problems Nov 11, 08
Chapter 23: Getting my feet in and out Dec 19, 08
Chapter 22: Streamlining is working Nov 25, 08
Chapter 24: Streamlining is beginning to work! Jan 1, 09
Chapter 25: Tuft Testing Mar 2, 2009
Chapter 26: Starting Over April 9, 09
Chapter 27: More Ideas for Starting over April 20, 09
Chapter 28: Show time! Aug 1, 2009
Chapter 29: Getting the big parts right Dec 10, 2009
Chapter 30: First evaluation from an outsider Dec 20, 2009
Chapter 31: Visit with Allert Jacobs Dec 24, 2009
Chapter 32: Prius Headlights Jan 18, 2010
Chapter 33: New Gears Feb 17, 2010
Chapter 34: New Mileage Records April 25, 2010
Chapter 35: The Quail Gathering of Motorcycles May 9, 2010
Chapter 36: End of the line with the Helix June 19, 2010
Chapter 37: Vetter Challenge Oct. 9, 2010
Chapter 38: John Keogh helps out Dec 8, 2010
Chapter 39: Working with Keogh Dec 17, 2010
Chapter 40 and up (Work continuing in 2011)
Designing the Last Vetter Fairing

Chapters 1 thru 39 (2007-2010)

Chapters: 40 thru 51 (2011)

Chapters: 52 thru 61 (2012)

Chapters 62 thru 68 (2013)

Chapters 69-up (2014)