Skip to content

Dr. Sprocket makes another house call! Cutdowns & Bobjobs, part 1

April 7, 2011

Straight from Rich Ostrander, aka Dr. Sprocket, this is part 1 of his story of the early modified American bikes.  To read his earlier article on Occhiolungo about his “Notes from the Old Days”, click here.


This site is predominantly reserved for the the history, preservation and restoration of our two-wheeled heritage as it relates to dealer or factory offered street or racing machines.  I’m going to go out on a limb here an offer you an article on “modified” motorcycles.  We’ll cover the earliest twenties “cutdowns” and the late thirties, forties and early fifties “bobjobs”.

We have examples of “as offered” stock restored or original condition machines from most of the countries in which they were offered today.  To find an original machine that has never been modified by its owner or a series of owners is a rare thing indeed.

Riders wanted their machines to fit them as regards to handlebars, seats, etc.  Many aftermarket parts manufacturers filled this need.  Many riders would also use their machines for off road work or in club contests and still use them for everyday transportation.  These modified machines are a large part of our two-wheeled history and should be preserved or restored and held in the same regard as their brother stockers.

I was thrilled when Kevin Valentine and myself were able to put this point across to the AMCA (Antique Motorcycle Club of America) some years back.  We now have a class for Period Modified Motorcycles.  Because the 1915 to 1929 J model Harley Davidson motor was cradled in such a high center of gravity frame, rider who wanted a more “aggressive” handling machine would lower them by cutting down the seat post area and shortening up the gas tanks.  Hence the name “Cutdown”.



This really took off when the HD factory offered their hot-rod two-cammed JDH motor in the mid-twenties.  These machines became so formidable in competition that they were “outlawed” from formal racing events because the factory and dealers were trying to sell the newer VL’s and early knucklehead OHV models.

Riders in the thirties and forties stripped off their front fenders entirely or added the smaller and narrower British type.  They also removed the rear fold up hinged fender section.  This modification helped avoid wheel stoppage due to crumpled fender ends suffered in competitive events such as TT races and hare and hound.  (American TT races were run on dirt, unlike the Isle of Man TT races run on streets –Ed.)  Soon smaller headlights were affixed and removed for competition as well as more free flowing exhaust which was routed higher for more ground clearance.

The “cutdown” evolved into the “bobjob”.  Later in the early to mid-fifties small English gas tanks and fenders were added and the bobjobs became the first “choppers”   Not to be confused with the later 50’s and 60’s style chromed, stretched, and molded custom motorcycles know as choppers.

For your viewing pleasure I offer you these photos and description of our modified two wheeled history…


#1  Three members of the Oakland Motorcycle Club in the Oakland hills with their J model cutdowns.  Probably early to mid-twenties as no front brakes are in evidence.  Special note of the center machine with the rear cylinder blanked off to make a 500cc single.  You can tell how low the frames are and the pocketed tanks to clear the valve train.



#2A  Basil B. Decker of Washington State astride his “Sam Oppie” Special.  Sam worked for the Seattle HD dealer and built about twenty to thirty of these cutdown two-cammed specials.  True hot-rods!



#2B  Andy Decker, Basil’s son in the 1960’s with his father’s Sam Oppie Special.  Note how the early thirties decals have been exchanged for the 1940 metal emblems on the gas tanks.



#3  The same machine acquired from the Decker family by a friend of mine a few years ago.  Note the cutdown and reworked seat post area and the rakish looking shortened and tapered rear gas tanks. scan0003


#4 & #5  This is a Finnigan Spear JD cutdown.  He and his brother Pat worked around the Dudley Perkins HD San Francisco dealership and built more than a few of these cutdown hot rods. scan0004



#6  This is the same machine as the above two photos after being restored by Dale Axlerod.  He added earlier model HD gastanks, modified other pieces, and added a two cam motor.  They never looked this good back in the day. scan0006


We had Sam Oppie in Washington, the Finnigan brothers in SF, and Lance Tidwell and John Cameron in the Southern California area.  #7A&B  This is a Lance Tidwell two cam cutdown restored by two cam specialist George Hood for my old friend Chuck Vogel.  Note the shortened tanks, shorter front forks, and really low seat post area.




#8  This machine was Lance’s personal ride in the 70s and early 80s.  John Cameron and Lance rode their tow cutdown JDHs from LA to Sturgis about that same time period and they weren’t spring chickens either at the time. scan08


#9  The man himself, John “Two Cam” Cameron.  An original Boozefighter and cutdown specialist.  This is a photo taken in the late 80s at the Fort Sutter Chapter’s First Lake Tahoe National Road Run.  His grandson Craig Taylor still has this machine today as well as the one in the next photo. scan09


#10  Another Cameron two cammer with a British 4 speed transmission.  Lots of handmade custom part on this cutdown. scan010


#11  My friend and first Ft Sutter Chapter President John Schaefer’s two cam cutdown at the same Lake Tahoe Road Run.  His son now has this machine in Washington State. scan11


#12 & #13  This two cam JDH lower end had a 1941 OHV 74” (first year) upper end grafted on by Edgar Long in 1956 with knucklehead tanks fit to the JD cutdown frame.  Whew!




#14  Another JDH cutdown with neat front brake mounted.  I found this cool example at one of Dick Mann’s early Sandhill Ranch events in the late 80s. scan14


#15  Tom Sifton’s personal “first real hotrod”.  He fitted two-cams in a JD motor.  It was a sleeper that rocked the Bay area back in the day.  Looked like a single cam motor. scan15


#16  Stephen Wright’s JDH cutdown with ace restorer Johnny Eagles observing.  Stephen hosts a pre16 ride annually out of Atascadero, CA and is a restorer and author of much acclaim.  Loads of his beautiful handiwork on this machine.  Tapered Ricardo cylinder are attached also. scan16


#17  Dale Walksler of the Wheels Through Time Museum is the keeper of this original Stockton, CA cutdown built by John Billaborgli.    It is a JDBC not a JDH and also sports ultra rare tapered finned Ricardo cylinders. scan17


#18  Another of Dale’s cutdowns. This is a JDH with the rear cylinder blanked off like the photo of the Oakland M/C boys machine.  This as found machine was originally built in Modesto, CA.  Note chromed VL front forks (rear leg) with earlier castle front leg.  Lots of extra chrome and custom paint.  Super cool period hotrod. scan18


#19  Chuck of Kick Start Motorcycle Parts in the mid-west found this cutdown with a JDH motor married to a knucklehead OHV upper end.  I’ve seen about three of these setups over the years.  Best lower with the best upper Harley ever built.



#20 Chuck again with a friend and his friend’s (unknown to me) JDH cutdown fresh from restoration.scan20


Finally here’s the last two JDH cutdown for your viewing pleasure.  These two belong to RL Jones on the East Coast.  Owner and restorer of many historical early racing and hillclimbing machines.  #21  Lance Tidwell SoCal style JDH cutdown.


#22 JDH cutdown with rare rear mounted later style magneto fired ignition.  Also has extra rear leg for reinforcement like some factory hill climber frames had.



That’s all the cutdowns folks!  You can see how some of them tapered down in the rear frames and tanks influenced the factory offering In the mid-thirties.  Take the rakish 1936 knucklehead HD and Indian Chief.

Stay tuned for Part 2, where we’ll move on from cutdowns to bobjobs, with another 30 photos from Dr. Sprocket of Crockers, Indians, HDs and more.  Here is the link to Part 2.

15 Comments leave one →
  1. April 8, 2011 12:36 am

    fantastic article….

  2. Somer permalink
    April 8, 2011 6:45 am

    Great series of pix.Thanks!

  3. April 8, 2011 10:50 am

    Whow, what a great post. Thanks a lot for great pics and words to Dr. Sprocket.

    AMCA 3489

  4. April 8, 2011 12:00 pm

    GREAT post. Thanks.

  5. April 8, 2011 12:25 pm

    Great stuff, and an education too. The period photos are excellent!
    It’s interesting that home tuners of HDs ended up making something very similar to factory racing Indians ca 1926;

  6. Dave Minerva permalink
    April 8, 2011 3:47 pm

    Killer article and pics. Thanks

  7. Rick Haner permalink
    April 8, 2011 5:41 pm

    awesome article me fired up to do finally do something with the 26 motor sitting on my workbench for the last 10yrs,for which I have always wanted to build a proper cut-down..!..the frame tech”how to” was the bomb…now I know how it was really done…thanks for all the research…..

  8. April 9, 2011 1:33 am

    Amazing insparation from these pictures. I will for sure build a cut down now with a 4 5/8 stroker JD engine.

    Thanks for the pictures and text.


    • Anonymous permalink
      March 7, 2013 5:04 am

      hehe now i have been riding the 4 5/8 stroker for 2 years , time for a 1700cc , T&O, Carillo and some other nice suppliers make this happends.

      Ride on


  9. April 9, 2011 1:34 am

    Anyone have a 25 – 29 JD frame for sale?
    valand at

  10. Eric permalink
    April 11, 2011 10:10 pm

    Picture #20 i think that is lance tidwell near chuck from kick start. Thanks for this article dr sprocket

  11. Anonymous permalink
    October 8, 2014 9:22 am

    Eddie Long’s knuckle also had aluminum cylinders.

  12. Anonymous permalink
    June 24, 2015 3:33 pm

    Dr. Sprocket, you are a treasure. Tom Roberts Las Vegas, Nevada.

  13. Anonymous permalink
    April 9, 2017 2:25 am

    Fantastic article… thanks!


  1. » Blog Archive » Cut-Downs and Bob-Jobs Explained.. Good Stuff from someone who actually got it right..

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: