The Nickle and Dime Express: a Not Really 1946 Harley UL Big Twin Flathead

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The transmission is nothing special -- just a regular four speed. We are going with a BDL 2" belt drive for the primary, but that's not exactly exotic.

Because we started with bare cases, we had a little more fun with the motor.

I have a nasty habit of not being able to leave motors alone for long -- most often over boring and or stroking. This one got stroked.

We went with a set of 4-3/4" wheels from Truett and Osborn. In a previous life, I did a lot Corvair work -- specifically turbo charged 'vairs. A call to Clark's Corvair parts netted me a set of turbo pistons -- STD for the front and .020 over for the rear. Remember, the 80" flatty isn't a true 3-7/16 bore; it's small. So, the Corvair std piston is already at 10 over on a std HD 80" bore. And, yes, you can run different sized pistons. It was not worth boring the front to match the rear.

When stroking a motor, there's not free lunch, so everything needs to be checked. Here I am mocking up piston skirt and connecting rod clearances.

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The downside to using Corvair pistons is that the piston pin is .801 instead of .792 -- so you have to open up the small end of the rods. Similarly, Corvairs are captured small end with free floating pistons. Harleys are full float. So, you either have to add circlip grooves to the wrist pin bores (not so bad with a fixture) or make alloy pin buttons to match each bore. Note I said match each bore. Unlike pin buttons in say a SBC application where you use the oil ring as a lateral location -- there's nothing to locate the pin button in this configuration because it is a slipper skirt piston. So, they need to be press fit pins and radiused -- as well as create an overall pin length that takes into account expansion. Years ago, I ran into a set of radius tool bits at a garage sale - so I was set there. It was just a matter of calling a few people to see what they had used in the past for end clearance. Then, make em up -- press em in, and face to length with the radius tool. The advantage of this system is that you can stage the piston and rings in the cylinder and simply plop the in into place during final assembly.

From all the mock up we learned that with .050 base plates we'd have zero deck using the Corvair pistons. This meant I could set the piston to head clearance with custom thickness head gaskets. Enter Cometic gaskets in Concord, Ohio. A quick ring to Cometic saw me sending off samples of head and base gaskets. A few weeks later, I got back a pile of custom head and base gaskets in various thicknesses. Yippee.

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Here's that pile of base and head gaskets from Cometic:

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because I sent them the patterns -- you can now ring them up and order base or head gaskets in any type of material you prefer and any thickness. Turn around time is very fast and they are quite affordable.

The connecting rods were magnafluxed because we are using a pre-39 open window female rod. These are known to crack, but we had no issues. The rods didn't need rebuilding and the races trued up with a light hone on the sunnen. The rods were polished and shot peened -- along with new small end bushes bored and honed to fit the corvair pins.


The cylinders were honed using a sunnen porta hone and torque plates to .006 clearance and we went with a set of Hastings moly faced rings meant for turbo charged Corvairs. These should deal with the higher heat load of the flatty well.


I balanced the crank at 54.5% -- you can really choose what ever factor you like. 55 seems to work well for long stroke bikes ridden at moderate speeds . . .so there you go. One thing we did try on this motor is drilling an "oil flinger" hole. We found this idea in Rick Schunk's panhead book and it was used to help deal with a wrist pin oiling issue on a knucklehead. Basically, you rifle drill a passage at an angle from the inner part of the pork chop to the outside rim. The idea is that oil winding down from the crankpin intersects the pork chop and gets flung to the outside anyways. The rifle drilling allows a metered amount to get flung as a stripe right into the underside of the piston at BDC. This is sort of like a passive piston squirter. Not going to be as effective as a squirter, but should show better wear patterns than stock. We will find out in 10,000 miles :-)

Valves are oversized 2-1/8 -- the cylinders got a full valve job with new kibble white guides, the new oversized SS valves, new springs, retainers, everything -- cause, well, I had to buy everything! The cylinders got relieved and then everything got coated in thermal barrier coatings and dry film lubes. Why not -- might as well give it a try.


The only thing that was a true challenge was the JIMs pinion shaft. To put it mildly, it was machined incorrectly. I wound up custom grinding the OD and the splines to make it all work. I also was not happy with the quality of the cam chest bushes I bought. So, I grabbed a bar of SAE660 bronze and just made the bushes myself. I wound up making two case bushes, one timing cover bush and the pinion bush. I also installed a 4 vane oil pump conversion. Breather was retimed and I even graphed the cams for a fellow enthusiast.

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The motor fit together very well for components that had never known one another.

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And here's a couple of the motor rough mounted just before I moved to the new shop.

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The flat head really tucks into the duo glide chassis nicely. The seat is also adjustable in height up to 2.5 inches. The rear bar is slotted and with a wrench you can move it up or down to suit your need that day of the week. I find sometimes my back is feeling like it needs a different angle and so there are days I don't ride certain bikes. I built this one so I could move the seat angle for those days if I was in the mood to ride it.

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Even though this is a low compression bike (6.7:1), I added one of Morris Magneto's MRA caps to the bike. It allows for up to 20 degrees of retard on the ignition. It tucks in there quite well to boot.

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Couldn't resist a little close up shot:

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And, thanks to the Fabers, I can even have a Chicago Motorcycle Supply kicker pedal to match my Chicago-born Frankenbike.

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I know that bikes like this irk many in our antique motorcycle community. I understand and appreciate that -- and hope everyone reading this understands I did not kill a good bike to make it my own. Instead, I took parts collected over many years, took off cast at swap meets, and generally used the worst condition parts I could find to put a rider together.

This bike is titled as a 1946 UL -- but I would never dream of pretending it is such a bike. It's not. It is a rider put together out of bits.

But, unlike many of the "choppers" that are all over the internet and TV -- this one is all HD and retains all the functionality of the original bike. No floppy long front and rigid rear welded on. It wasn't bought out of a catalog and there's not really too many like this running around. That's not a badge of honor for me -- it's just my frugal nature. Have junk parts -- have little cash -- will still build a bike that doesn't suck. This one has full front and rear suspension and brakes with the hydraulic rear brake coupled with a Triumph TLS front. I made the majority of the hardware and took the time to use only three sizes (1/2, 9/16, and 5/8) to minimalize the tools needed in the tool box (yes, it has a tool box) so that I can strip the bike down on the road if needs be. There are a few 7/16 fasteners, but basically, you don't need much in the way of tools to take this bike down to the frame. That makes it a bit more "user friendly" when exploring the wilds far from help. Not exactly a lot of folks can help you sort out a custom bike with prewar components -- so you need to think just a bit about how you do things if you plan to ride the dickens out of it.

One thing I didn't do was bother with a speedometer/odometer. Instead, I have a magnet mount for my phone. Just plop it on the bar mount and dial up the GPS, which gives me my exact speed. Fill the tank now and again - and we are good.

I also added a sight glass to the oil tank. This isn't a hipster addition. Because of how I configured the seat -- the oil filler and dipstick are not as readily accessed as on a stock bike. You have to unbolt the seat. I'll do that to add oil or change oil -- but not to check if I have enough oil. Experience says that if it's tough to check the oil level -- you won't. So, I added a sight glass to the tank. At 3 quarts or above, the sight glass will be filled. If you can see light, you're below 3 qts and at the bottom of the glass it is just under 2.5 quarts in the tank. Viola -- easy to gauge if a bit hipstery. It did take a while to fill the tank with alcohol and find those quart levels. I had to do it on the bike to match the angles . . .well, I didn't "have to" I just wanted it to be accurate enough that it functioned as intended.

Ditto on the open belt drive. Not trying to be cool -- trying to minimize vibration and make life a bit easier overall. I chose the 2" unit because it doesn't stick out as much as a 3" but also is a bit more robust than the 1.5" units. Not that dramatically more robust -- but enough to make me sleep better at night.


Because I stripped so much weight off the bike it is surprisingly light --- so all that brake can actually work. Yes, the hand shift does make it more difficult to ride in modern traffic and is a bit hipsterish. You got me there :-)

[JoJo357]

Thank You Steve, i really enjoyed your transformation. Reminded me of simpler times with not a lot of Money to play around with. But, in the end run--there was something to ride and be proud of.

*M.A.D.*

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I got down to finishing some details on the flatty over the weekend. Big things were finishing up the wiring, making up a set of HT leads for the magneto, and installing the primary/rear chain.

I have to admit being a bit trepidatious about the primary install. I have rather limited experience with belt primaries on big twins and had not previously installed one myself. I was prepared to have a nightmare time of it . . . but in reality it fit together with no issues. Pulleys were in alignment. Go figure.

I also wound up doing some frankenstein work to the fuel supply and oil lines. Because I'm using a sportster tank -- the bung is on the right and forward. The only reasonable petcock choice has to be pretty short so as to not foul getting at the head bolts for retorquing, etc. Similarly, because we have to run the line either over or between the cylinders, a piece of soft tubing is 50/50. To deal with it, I grabbed a short length of NiCop tubing and bent it to fit. At each end, I connected it to hose barbs with short lengths of soft tube. Though NiCop can easily handle vibration and doesn't readily fracture -- the soft lines eliminate any chance of vibration related cracking or olives not sealing well in the carb compression fitting. I simply cut a barb off another fitting and machined it to fit in an original 7/16-27 carb nut. I added an o-ring and all is leak free. Colony sells this adapter for linkerts . . .but what's the fun in that?

here's some glamour shots:
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more glamor shots:
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The primary tucks in nice and tight. With the rocker clutch and square foot boards, there is limited risk of losing my pants to the belt!

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Another thing I did on this bike was to use the top motor mount as the horn mount. Normally, tucking a horn in like this means you'd kill the tone a bit. However, I got around that by installing a 6 volt horn without a balast resistor. This means it sees 12 volts and is LOUD. Really LOUD. You won't burn up a horn coil unless you just lay on it for a long time.

But, by tucking it up I was able to use the power feed terminal to also pass power forward -- thus cleaning up the wiring.

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I also made use of integrated LED markers in the license frame. These lights were really inexpensive and operate from 4.5 to 24 volts without a resistor or reg -- which is just about perfect for a magneto fired bike. I did decide to mount the license off the left shock -- mostly because I didn't want to add a horizontal tag holder to the rear of the mud guard.

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A buddy asked how I solved the lack of a steering head stop . . . no problem.

I molded in a 3/8 rod to the very nose of the steering neck. It contacts the lower tree stops. Maybe not as "elegant" as internal stops, but every bit as functional and no "special" parts in the steering head.

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And here are a few shots of how I did the TLS Triumph brake conversion. I chose the 1968 style actuating levers because they pull "back" vs. the later TLS system which pulls "up" like a typical HD system. If I still had a fender - I would have chosen the later version. Instead, I needed the loop and then a clip to hold it all away from the wheel.

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A couple of other minor details to help folks out thinking about different ways to do things.

The rear fender/mudguard is a 1967-up rear fender for an XLCH sportster. Many of these fenders crack near the "notch" for the rear chain. This fender was no exception and had several holes in it plus some dents, rust, and fuggly paint.

To deal with the crack -- I simply cut it off. The first few inches of the fender were cut off. I then rotated the fender forward so that the former rear edge of the fender was just a few inches trailing the rear axle centerline. Experience says that if you have fender that is leading the axle -- you "may" avoid getting tagged by pebbles. If you trail -- then they tend to never find you. In either case, they are still pitiful for rain duty -- and the lack of a front means rain will certainly find you. But, I really hate getting pegged in the back by a pebble. This one, thankfully, fit ok.

If you're looking at the pictures, it seems the fender sits really high -- that's just a quirk of how the duo glide frame sits. Once you're sitting on the bike, it all evens out.

Back to the fender -- all I did was cut a pattern out of card stock and weld it over the former tailight assembly hole. I then screwed the base plate for the Mack truck marker lamp to the centerline of the fender. Because the lead I used won't stick to alloy/potmetal, I was able to mold the exact shape of the taillamp into the fender, then remove the lamp housing. The lead is much stronger than body filler and while it adds weight to the fender, the resistance to cracking is what I'm after here.

So, here are the photos -- you can just make out the vee fore and aft. It looks better in person without the odd reflections.

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Two more mostly dead parts returned to service.


Similarly, when I did the site glass, I did buy a catalog part. I bought the components from Billet Proof, which sells this as a threaded cup for the sight glass (which is a standard item you can purchase from most industrial supply houses.) The cup saved me a ton of fabrication time -- all I had to do was use a hole saw to cut the ID, weld it in, do some light body work, and then test for leaks. Considering this tank cost me $10 off the "please take it" tarp, I was happy. And, it functions exactly as intended. At a glance, I know whether I have sufficient oil and shortly after start up, I should see some good "bubbly" oil. If I don't -- then I know I'm not getting return (or not enough return). Remember, I'm running a magneto and no battery -- so traditional warning lamps aren't possible. The sight glass is simple and effective, if a bit on the hipster side.

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And, yes, you can fit earlier rectangular boards on a duo chassis.

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And, another buddy asked me what the heck I meant by frame "molding." Many of you may be familiar with this term from the 60s/70s when slathering bondo all over a frame to create a "smooth" look or even different shaped tubes was popular. Invariably, the molding was over done and today it's pretty common to find molded frames with cracking and failing filler.

But, the idea was to smooth out all the joints in a chassis so that everything flowed together or like it was sculpted/molded from one piece.

Because this frame has so much damage and I was not restoring it -- I covered repairs and molded. The molding was done 90% with Johnson's Lead Free Body Solder with just a smear of Rage Evercoat Filler to finish it off.

Here are some examples.

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Again, not everyone's cup of tea. I understand some guys would have spent the $$$ to restore this frame . . .but keep in mind it was destroyed enough that he original date codes and other details were completely gone. So, good for a rider.

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Hopefully we will finish up the exhaust this week and finish routing the front part of the rear brake line. I also have to tighten up a few things, install the clutch release, and put the correct terminal nuts on the spark plugs. But, with that, this pile of junk parts should be rolling around again for the first time -- ever.


This particular project taught me more about how Harley actually built bikes than any other. When trying to figure out what actually fits (not what a book or mythology says fits) and how it all works together I had to talk to a lot of AMCA members and consult literature in the Virtual Library as well as my own books and of course Bruce Palmer's tome.


In total, I invested more than 650 hours in this project. A more typical motorbike rebuild like the Guzzi I shared or my '64 Sportster take more like 200-250 hours. Research and calls easily took up another 100 hours.

Don't think I'll be doing another one like this -- but it sure was fun in its own way.

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Got the exhaust mounted, rear brake hooked up -- and just waiting to go to the station for some fuel.

I had hoped to bring her to Wauseon with me . . but there's always 2021.

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A few more views:

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