1/8 Scale Harley Knucklehead Engine. Complete Running Model Coming soon…


His name is Jerry Kieffer. He is not a professional machinist, but a retired field representative for a Wisconsin power company who turned his home shop into the finest and smallest examples of model engineering to be found anywhere in the world. He has been building a number of incredible projects, including two miniature Harley Davidson motorcycles, a 1/8 scale John Deere tractor, several other steam and gas engines, clocks, etc. He owns a 1947 Knucklehead Harley Davidson that he completely restored. So he measured each and every part of the his bike to make the scaled down parts for his model. Yes, the full motorcycle is in process with the motor running and all the systems working.

He wants this tiny engine to start with a kick starter just like the real engine. He also wants the gearbox to function and the speedometer to work. And if you are not still not blown away by the talent and dedication of Jerry Kieffer, think about what is involved in this -lifelong? – project. Of course, 1/8 scale means 8 times smaller, but keep in mind that when reducing in size, the part size goes down as a function of the cube root of the volume, not as a simple linear reduction.

For example, the volume of a part at 1/2 size is actually 1/2 the length times 1/2 the width times 1/2 the height. That means the 1/2 size version of a 1″ cube would be a cube .5 x .5 x .5 or .125 cubic inches—1/8 of a cubic inch. A1/8 size model of a 1 inch cube is .125 x .125 x .125 which equals .00195, or less than 2 thousands of a cubic inch! For example, the smallest bolts on the factory Harley Knucklehead engine were 1/4-20 size, which translated at the model size are  bolts smaller than ten thousandths of an inch in diameter with hundreds of threads per inch at 1/30th scale! There was nowhere to go to find threaded tiny parts that small. Giving up? Of course, no. After many efforts at trials and errors Jerry developed techniques of making extremely small taps and dies and succeeded at making tiny hex head nuts and bolts. And jerry states that “Making them is easy. It was figuring out how to make them that was hard.” At least, when his project is completed and running, I hope that Harley-Davidson will honor him with a permanent exhibition spot at its Milwaukee Museum. Jerry Kieffer.

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18 Responses to “1/8 Scale Harley Knucklehead Engine. Complete Running Model Coming soon…”

  1. 1 Dave Blevins Feb 4th, 2010 at 9:02 am

    Very cool. Very cool indeed.

  2. 2 Brett Feb 4th, 2010 at 10:19 am

    Man click the link…there are pictures of the frame & springer…..It looks very cool

  3. 3 John K. Endrizzi Feb 4th, 2010 at 11:05 am

    Knucklehead Company M/C held it’s Knucklehead Reunion at the Harley Davidson Museum last July. We were lucky enough to have Jerry as our honored guest. He was on hand to demonstrate his very special talent. We will do the Knucklehead Reunion VIII at the Museum on July 10, 2010. Hopefully Mr. Kiefer will join us with examples of his amazing work.

  4. 4 Jeff Nicklus Feb 4th, 2010 at 11:44 am

    Now this guy is a true craftsman!

    Over & Out,


  5. 5 tattooeddmike Feb 4th, 2010 at 12:19 pm

    Too Freakin COOL!!! What a talent! I hope to see this one day.

  6. 6 gabehcuoD Feb 4th, 2010 at 1:40 pm

    The size of some of those nuts and Swagelok fittings are really just insanely small…. WOW

  7. 7 Rider2 Feb 5th, 2010 at 1:22 am

    How much???

  8. 8 jatinder pal Feb 5th, 2010 at 1:26 am

    Awesome,this guy is artist..look at the details…cool.

  9. 9 freedomlaw Feb 5th, 2010 at 7:31 am

    I love this blog. I love this blog. I love this blog! I am constantly blown away by the variety of interesting information, from old Triumphs to this. Thank you Cyril. Until your explanation, I had never thought of the (now obvious) problem of three dimensional volume in making scale models of things. It just adds to my appreciation of the final product.


  10. 10 madpuppy Feb 5th, 2010 at 7:39 am

    WOW ! Just amazing. I also like the restoration on the 1947 Knucklehead , perfect right down to the oil catcher on the floor. lol

  11. 11 maroco Feb 5th, 2010 at 9:56 am

    Very impressive, talent and knolege!
    Congratulation, this product have great chances in the market!

  12. 12 cwglide Feb 5th, 2010 at 12:49 pm

    I was impressed by the springer front end. Question; Where can you get a spark plug that small? Hell he will probably make one. This dude is talented, and true craftsmen. Thanks Cyril!!

  13. 13 John K. Endrizzi Feb 5th, 2010 at 5:47 pm

    I corresponded with Jerry yesterday. With the time he has invested in this project :
    1) It is not for sale
    2) there will be no duplications.

  14. 14 Jim C Feb 6th, 2010 at 10:46 am

    absolutely incredible. that is what sheer determination,focus and the love of being totally involved in what you are doing is all about.

  15. 15 MDK Feb 8th, 2010 at 10:01 am

    That is sweet! Reminds me of the miniature Ferrari the fellow in france built.

  16. 16 Mazz Feb 8th, 2010 at 10:09 am

    That’s groovy insane!!

  17. 17 nicker Feb 9th, 2010 at 5:10 pm

    When the motor’s finished he needs to stuff it into this:



  18. 18 clifford e. mcoueen Aug 23rd, 2010 at 8:08 am

    i would like to talk to this man i need a sit of 1:8 headers to but throug or clue on my i:8 gravedigger
    modle it is elec so they don’t need to be funcal just for looks

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Cyril Huze