Back To The 45’s Flathead









Got an old “Flatty”? (I am searching for a good one..). Look at what you can do with it when using the new components offered by Paughco to resurrect the 45’s. You can buy from them their new rigid frame and transmission plate (don’t use the 3-speed an replace by the 74 4-speed transmission), tapered leg Springer , wheels, seat, tanks, transmission plate, pipes brakes, etc (you can order the full chassis). It’s a quite simple bike to build in a short time when you know where to source all these parts. The red bike was assembled by Dave Perewitz and this style is the new cool thing to build & ride. Paughco.


38 Responses to “Back To The 45’s Flathead”

  1. 1 Kirk Perry Apr 10th, 2009 at 10:01 pm

    Yeah they’re cool. Cheap to build. Look pretty good. Surface streets only maybe, but that’s OK, freeways aren’t much fun with old iron. The 4 spd trans. option is cool. What speed do they truly cruise at, without feeling like you’re winding the snot out of ’em? 45-50 mph? That’s fast enough. Nice bike.

  2. 2 Lyle Apr 10th, 2009 at 11:24 pm

    A good 45 will cruise at 60 mph easy. I’ll tip my hat to Paughco for this one!…..

  3. 3 Grayhawk Apr 11th, 2009 at 1:10 am

    One might consider using a British 1960’s 4 speed as that woud give you a better chance to reach the 60 mph alluded to above and it is a stronger tranny as well as the extra gear. There are instructions on the net showing the conversion. This has been done on the original 45 setups for years. Building the big flatties 74 and 80 cubic inchers, VL,VLH, UL, ULH motors gives ya a bit more oomph, heavier frame though, and you can get 4 speeds for them HD option starting with 1936 VLH model. But there are lots of the 45 motors around, especially WL, WLA, WLC military and the G servi car motors, the 45 was the most years running HD model motor every made.

    Let us not forget the Indian flatties either. Mike of KIWI could chim in here on the Indians as well as plug his nice/functional leaf front end set-up, really cool.


  4. 4 Grayhawk Apr 11th, 2009 at 1:58 am

    Less I forget Paughco does a lot of good things and this is another I was just adding in the original concepts as well in my previous comment. It is all cool stuff. Noting the HD higher performance 45 motors are cool as well for use, WLD,WLDD,WLDR and of course the famous HD racing WR 45 ci motor albeit these original 45 motors are a whole lot harder to come across than the ones listed above. While I am at it if you go original parts and both ways are cool, just what floats your boat, do not use the original HD 2 bolt tranny frames straight front leg frames that were used on HD singles and the HD DL 45’s stick with the later HD 45 era solo and military 3 bolt frames or Paughco’s frame and go from there. Flatties are cool. Do not forget S&S has taken on the HD replica motor segment from Flathead Power a few years back and is taken that to the next level athough give credit to the Swed who started all that flathead motor replicas stuff years ago, mostly big flatty stuff though.

  5. 5 Grayhawk Apr 11th, 2009 at 2:19 am

    Sorry not meaning to crowd the blog and write a book but the purist out there will nail me for forgetting the RL series 1932 1936 45 HD motors as well to look for as they were the first servi car motors and solo 45’s after the DL series, their frames were not straight front leg but still had the 2 bolt tranny setup but one could look for those 45 motors as well to use in their setup. The DL motor will not work in either setup because of what was called the 3rd cylinder or vertical generator if you will. Hope this helps.

  6. 6 Marilyn Stemp Apr 11th, 2009 at 7:39 am

    Other goos sources for parts and info on 45s are: 45 Parts Depot, Truett & Osborn, and Warren Bennett at 45 Restoration Co. There’s also Custom Cycle Engineering and Steve the Brew Dude. My 45 build has been in the works for over a decade…

  7. 7 Kirk Perry Apr 11th, 2009 at 8:38 am

    “My 45 build has been in the works for over a decade…”
    Which begs the question, “Which cherry parts are not made for the 45 (the parts that everyone most wants most for a build?”
    Would that be the crankcase? Or the lifter blocks, or the aluminum heads?
    Whatever these parts are, can’t someone like STD or S&S make them? Why spend valuable time searching for parts.
    I think somewhere along the line, the Repop builders should go back to the “49 state” U.S. flag as a trademark and leave California out.

    Yo’ Arno !! (yea youse! Arnold Schwartz!), the planet is already melting faster than an ice cube on a hot skillet. We can’t stop all that by restricting fossil fuels in one state. Whaddayanutz?

  8. 8 Puzzled Apr 11th, 2009 at 11:55 am

    Great frame. Love the design. One thing bothers me, I thought the single loop style frame was patented and owned by U.S. Choppers. Am I mistaken?

  9. 9 THUG CUSTOM CYCLES Apr 11th, 2009 at 12:57 pm


  10. 10 Gregory Schmidt Apr 11th, 2009 at 1:40 pm

    To Puzzled. The single loop frame is not, and cannot belong to US Choppers. It was created before the owner was born! It belongs to nobody, can’t be patented, and anyone can manufacture one. Just marketing intox!

  11. 11 Bobfather Apr 11th, 2009 at 6:04 pm

    Nice stuff, always love seeing the old school look being done.

  12. 12 Lyle Apr 11th, 2009 at 9:43 pm

    Single loop has been around since before WW-I.

  13. 13 Dave Blevins Apr 12th, 2009 at 12:39 am

    I’ve wondered for a while if S&S (through the Flathead Power brand) might start doing some 45 stuff, I suppose the 45s are a very niche market and the lagging economy is reason enough not to… but I wish they would! It could be really cool.

  14. 14 Puzzled Apr 12th, 2009 at 6:31 am

    Not too sure about that. It seems to me that thay have stated they own that design. How can this be verified?

    right off the US Choppers website

    ” Features our patented neck design coupled to a single loop engine cradle “

  15. 15 Eric Cook Apr 12th, 2009 at 6:41 am

    Hey Puzzled! You just stated yourself” “patented neck design”, not patended “single loop engine cradle or frame”! By the way, patented neck design? For what? You should ask for the patent number of the neck design, if any…Then publish it here.

  16. 16 Puzzled Apr 12th, 2009 at 6:44 am

    Hey, I am not in any way associated with US Choppers or any other frame company, Nor do I want to be, I’m Just asking questions here.

  17. 17 John B. Apr 12th, 2009 at 6:45 am

    Eric is right. As far as I know, there is not such a thing as a patented motorcycle neck design.

  18. 18 Puzzled Apr 12th, 2009 at 7:01 am

    Why would someone advertise that if it wasnt the case I wonder?

  19. 19 Brea Apr 12th, 2009 at 7:20 am

    To try to discourage others to do the same frame…when they can. Single loop frame? Was used at the time of WW1 by most manufacturers. Many builders have done a single loop frame bike, even Cyril (see bike called Bombshell in his website)

  20. 20 Puzzled Apr 12th, 2009 at 7:34 am

    I wonder if a US Choppers rep. would like to comment on this sometime to help clear the air?

  21. 21 rock star Apr 12th, 2009 at 12:58 pm

    nice bikes.

    very nice.

  22. 22 Lyle Apr 12th, 2009 at 8:28 pm

    Single loop was first done (I think) in 1904 by James. Not sure how if can be patented after so long. Patents don’t mean crap to smaller companies anyways as they offer no protection.

  23. 23 Curt! Apr 12th, 2009 at 10:39 pm

    PLEASE !! PLEASE!! Do not make the 45 chopper popular. They have long been the lone Harley a guy could build on a low budget. If you high rollers come in and start making all sorts of billet shit for 45s the lemmings will drive up the prices, then what is a blue collar guy building on a budget going to do? I love my 45 and it will probably last me a lifetime so I’m not terribly worried. I aspired to own a Big Twin Flathead until they became the ‘must have” custom. Now, that dream has died.
    No offense, Kurt.

  24. 24 George A., Detroit Apr 13th, 2009 at 3:08 am

    According to the U.S. Choppers Website, says the thing is patented by them. What gives?

  25. 25 Brad Solte Apr 13th, 2009 at 6:39 am

    George. The single loop frame by itself belongs to nobody. The loop design cannot be patented. A patent can be given only for a new/original design. Frame looop design s almost as old as the 1st motorcycle and used by many.

  26. 26 My Evil Twin Choppers. com Apr 13th, 2009 at 11:07 am

    Awesome thread Cyril.

    I just finished a 45 motor and I’m looking for a frame to put it in. I started looking in my Paughco catalog but I’ve entertained the idea of a Kiwi frame too.

    Nice to see 2 stunning bikes together right along the lines of what I was thinking.

    Leave it to Dave to build such a beautiful putt.


  27. 27 LENNY SINNET Apr 14th, 2009 at 2:55 pm

    now that is the best answer to bike building with the recession . 45 motors and 4 speed transmissions are everywhere a bike like this can be built at an affortable price. classic and affordable very kool nice job…Paugcho sure put the name classic in clasic motorcycle

    Evolution Industries

  28. 28 Nicker Apr 15th, 2009 at 12:10 am


    “… PLEASE !! PLEASE!! Do not make the 45 chopper popular….”

    Not to worry Dude.
    As long as they remain “kick starters”, no “lemmings” will apply…. 🙂


  29. 29 Sven Apr 15th, 2009 at 12:38 am

    The Harley Davidson WLs and dirivitives such as WLA and WLC all have “single loop” frames.
    Many of the preceding models also had single loop frames.
    All the way back to Harly Davidson’s earliest models.
    Even before WW1.
    You only need to look at old H D sails catalogues, biker mags and photoes on line to see this.

  30. 30 Sven Apr 15th, 2009 at 12:58 am

    Sorry Curt,
    WLs make great Bobbers and choppers.
    My 1946 alluminu head WL was chopped around 1960.
    It was and is very old school!
    Which in my oppinion is the best way to do an elderly bike.
    Do as much of your own work as you can.
    Get your friends to help.
    I designed the exaust tubes and had a local mufler shop bend them.
    I also fabbed the necessary brackets of stainless stock.
    I fabbed the full length dash of 16ga. cold rolled steel.
    A friend uppolstered it with leather and showed me how to cover the seat.
    Which I hammered out and made brackets for.
    I also made the brackets for mounting the Washington State reqired front fender.
    There’s not a bit of that billit shit on my ride.
    Do it “Old School”.
    Do it yourself.

  31. 31 Grayhawk Apr 15th, 2009 at 10:34 am

    Sven, close but no cigar the 45 original frames were single down tubes straight and then curved but not loop frames as they had a casting section cradling under the motor. Loop frames ended around 1924. Sven, sounds like you did good on your ole 45, keep them living.

    Additionally the 45 servi-car in its later years was the first electric start fitment, some think it was the Panhead but GE motors/Trikes fitted with electric start came out just prior to the Panheads introduction , as such one could build that 45 with a button but who would want to unless you have a problem kicking the bike over. The 45 will never maintain highway speeds for any substanable period of riding even with the extra gear. So they will not be for the masses but cool for puttin around and the most economical to build.

  32. 32 Sven Apr 20th, 2009 at 10:17 am

    So if someone wants to say the WL frames were not true “sigle Loop” frames because of the cast engine/ tranny floor plate,.
    Then fine, but many of the earlier models certianly had no such elliments in their design and make up.
    If that makes ther “true” single loop frames. O.K.

    I have been told by several very reliable sources that the engine/ tranny mount plate, steering head and other those other parts on W L frames which appear to be castings are actually forged steel.
    It would be cheeper and stronger to forge them . That’s for shure.
    They could even be forged ductile iron.
    I do not know.
    But that was very twenties/ thirties automotive technollogy.
    I have never seen one cut or broken so I have no idea about the crystiline structure.

    But the flatty is fun ride and a head turner too.
    I am blessed.
    I live not three miles from the late Jonny Bergens shop and Motorcycle Meusem.
    A couple of miles the rother drection and there is Harold LeMay’s old place.
    Jay Leno one said he wanted to have an auto collection like Mr LeMay’s
    There’s just huge resources and inspiration around here.


  33. 33 Cathy Jun 16th, 2009 at 8:29 pm

    This is to Sven…You mentioned The late Jonny Bergens and I am trying to find out where it is so that I can take my father to see the bikes for fathers day. I know that if you call and make an appointment they are happy to take you through. I hear telll that Jonny said that if he couldn’t share the bikes with others there was no point in having them. Could you help me out? Thank you, I appreciate it. I can be reached at

  34. 34 Rocket Jul 6th, 2009 at 2:00 pm

    I have a friend with a 45 looking to conver it to electric start – anyone have a source for the conversion kit ?
    Rocket – Jacksonville, Florida

  35. 35 pete Jul 30th, 2009 at 12:32 am

    how can ya go on and on and on about loop frames, who gives a crap, anyway – out of the bikes ive owned, my 45 is my favorite. they wont become very popular with most people cuz they are what they are nothing more nothing less, you build a relationship with a 45 over the years, they’re a friend, sometimes your fighting but you always make up. a properly tuned 45 does just what its supposed to, and they need to be touched with greasy hands to have that proper tune- mine anyway , i think these engines look sad in these ugly frames, 4spd, its like removing a good leg to put on a carbon fiber replacement, just an opinion- dont get crazy ——— pete

  36. 36 Greg Dec 14th, 2009 at 3:57 pm

    Dave Perewitz built the red one. Who built the silver one? Where could I find more pics and spec.?

  37. 37 Joe Feb 3rd, 2010 at 7:46 pm

    I’ve been riding a ’42 wla for 3 and a half years now and I love it. It’s still in the stock frame with a 4″ over narrow custom springer, mustang tank and the stock 3 speed. Now, my engine has had some work done, but it’s a fairly mild performance engine and I can sit at 100km’s an hour all day long. I’ve got over 25,000km’s on it so far and with new rings and a good cleanup it’s still going strong.
    What I don’t understand is how a 4 speed tranny is going to make my bike any faster. The gear ratio is still 1:1 in 4th gear the same as it is in 3rd(in a 3speed) so top end has to come from a smaller final drive sprocket or bigger motor sprocket. I have 34 tooth motor sprocket with a stock rear sprocket on mine now and the thing still pulls like a horse in 1st gear and lifts the front end end. Does the big twin 4 speed have a sufficiently different gear ratio in 1st through 3rd that I can lower my final drive with a much smaller rear sprocket and not lose all my bottom end? Because if not then I don’t really see the point of the 4 speed.
    On the flip side, if I was buying a frame like this I’d just build up a new mildly modded and stroked 45 engine and go for a Baker 6 in a 4 O/D box and get it over with. But maybe I’m wrong, I’m still learning here.

  38. 38 Mikko Jun 19th, 2010 at 3:24 pm

    Hello! I’m writing from Finland and I own 1944 sivilian WL-45 and she is so called “museum inspected” which means that she is really in original shape (and insurance-payments are really low). I like this kind of bike so much that I’m considering to buy another one which I can build to old school bobber. I ride my Harley very often and there is no problem’s whit her technical issues and I think that the original 3-speed tranny is quit enough for her. Last summer rear cylinder’s head was broken while I was standing on red light’s little too long time (it was really hot summerday). I purchased new one’s and while I was waiting for them my friend welded the broken one. Well, I haven’t placed the new one’s yet because welding old one was so succesfull procedure that she run’s like maniac with it. I really like simple and beautiful bike’s like flathead’s are!

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