Frankenframe: Ironhead rear frame section grafted onto an Evo Sportster

[alfajuj]

I mocked up the exhaust and am pretty happy with the result. I bought some drag pipes, because they're cheap, and cut them down to make them as head pipes, then added slip on mufflers. I like the look of that better than the one piece type systems.


I got the old Laconia bars all squared away. I wanted this build to be all traditional Harley parts, so I went with original bars, switch gear, and grips. The original internal throttle cable sheath (conduit) was really high friction, so I went ahead and put in an all new cable sheath. I adapted the stock 1988 clutch cable to work with the early style (pre 1965) clutch lever. It took LOTS of filing to open out the lever, and then to allow everything to have full stroke. It's good now. I repainted the original Harley instrument pod in crinkle finish black. I used an old 1976 FX Veglia electronic tach, since an Evo Sportster doesn't have a mechanical tach drive. I wanted a kill switch, so in place of the original odometer reset (the bottom center of the instrument pod), I put a latching push switch. This connects to a 5 pin relay that will interrupt the ignition circuit as well as the neutral and oil pressure lamps when pressed. At the same time it will also illuminate the blue high beam lamp, to let you know that the ignition is turned off. For this to work, there's a diode in series with the high beam circuit, so the ignition off mode doesn't turn on the high beam.
I thought long and hard about using a remote master cylinder for the front brake. But finally, I decided that a remote MC would be too complicated and just went with a 14 mm bore handlebar mounted master cylinder from some Honda. It's more honest. I chopped off the ball end and am polishing it to somewhat match the clutch lever.

Since the original eyebrow and instrument pod only allow for 3 lamps; oil, neutral, and high beam, I wanted something to remind me to turn off the turn signals, so I put in a relay to ground the oil pressure lamp when the turn signals are flashing. I also added a buzzer and mounted it in the location of the starter relay (under the battery box on the left) so the turn signals will beep loudly. That way I won't forget to turn them off.
I was going to use 1950's style turn signals, but when I mocked them up, they just didn't harmonize with the look of the bike somehow. So I went with these conventional 1970's ones.

I just love old school cad plated fasteners like flexloc nuts and slotted fillister head screws. It reminds me of the golden age of American industry in the 1930s-1960s.

[alfajuj]

The jugs finally came back from the painter's. I installed the 1200 cylinders. It was like crawling through barbed wire because the machine shop didn't put a taper on the bottom of the bore and I didn't have the right type of ring compressor. So I used a repurposed hose clamp and lots of finesse. The Keith Black hypereutectic pistons made it impossible to put the pistons in from the top and install the piston pins from the bottom because the oil control rings actually interfere with the piston pins. Anyway, the jugs and heads are installed, but when I went to put the rocker boxes on, I found that some numbnuts yahoo put in 3 exhaust pushrods and 1 intake pushrod. So I had to order an intake pushrod from the bay. I'm still waiting for it so I can put the rear rocker box on...I decided to put the exhaust system on while I'm waiting.

[alfajuj]

I've got the exhaust how I want it. They're just cut-down drag pipes plus cheap slip-ons. It was pretty fiddly to get everything in the right orientation, but now everything's good. The hard part is that the exhaust support is an ironhead part which bolts to the ironhead part of the frame, but the exhaust is coming from the Evo motor, so getting everything to line up and sit right is a challenge. It takes a lot of patience and a bit of fabrication to make it work.

[farmall]

Great stuff! Thanks especially for the sprocket cover info. The Ironhead fra,eback half is much more classic than the later style and the cover looks right with it of course.

[thecarfarmer]

All of this fabrication to replace a superior frame design makes no sense at all

Hell, it's almost as crazy as hardtailing the bike

So, of course, I think this project is absolutely tits!

Kinda makes me wish I had an extra hand, so I could give three thumbs up

[alfajuj]

Tits indeed!
I can't tell you all how gratifying it is to be understood!

[alfajuj]

The rocker boxes are on and I fired her up today! This is the first time she's run in over 25 years.
The carb is still a shit sandwich, but at least she runs!
I'm still waiting for the tank and fenders to come back from the painter's.
I still need to find a battery with enough current capacity that will fit in the battery box. Because of the mods I've done, an original style ironhead XLH/shovelhead HD12 battery won't fit in that space. I'm really happy how the gloss black primary looks. My intention was to make a stylistic nod to the black stamped primaries on the early XLCHs. I think it works.

[farmall]

Very nice. I like the shouldered alloy rims.

Would there be room for "more battery" on the left without hitting the riders leg/thigh?

[alfajuj]

I think the stock Evo Sportster battery or something like that will fit easily. I mean the big HD12 battery like on the 67 and up XLH and the electric start Shovelheads won't fit because of the way I had to reposition the battery box up and back.

[alfajuj]

When I test ran it, the carb was gushing gas right out of the float bowl gasket joint. At first I thought it was a stuck float valve, but the gas wasn't coming out of the drain. I checked around the joint with a feeler gauge and sure enough, the float bowl was so warped that a 5 thou gauge slipped right in at the back section. WTF. When I got the bike, this carb was missing some parts. Who knows how it got warped. Not having much of a choice, I decided to throw the dice and try one of those dirt-cheap knockoff CV40's. Sure enough, it had problems, but it doesn't leak and it does run...sort of. I didn't trust the jets, so I replaced the needle, emulsion tube, idle jet, and main jet with parts from CV Performance. The bleed hole in the vacuum slide on the knockoff was way too big (it was 0.125" instead of the stock 0.093"), so I used the vacuum slide from my old carb (I had just changed the diaphragm anyway). The accelerator pump was acting like it had a prostate problem. The spray was so feeble you could barely see it, and half the time it didn't pump at all. It turns out there's no check ball where it's supposed to be in the accelerator pump cover (You should be able to hear it rattle in there when you shake it). So I drilled into the boss on the cover to get behind the brass plug and tap it out. (Don't drill down more than about 7mm, or you'll drill away the seat for the check ball on the other side.) Then I put in a 1/8" check ball where it's supposed to be and pushed the plug back in. To plug the hole I made, I tapped it for an M4 set screw and zipped it up. Now it works. If you're interested in trying one of those knockoff carbs, You'll have to do what I did to make it work. I got the info from the web. http://www.performanceindian.com/Chi...ca%20CV40.html So yes, the Chinese CV40 clones can be made to work, but you can't just stick them on and expect them to run right.

[alfajuj]

Here's the accelerator pump body from the Chinese CV40 clone. You need to get behind this brass plug to push it out so that you can put in a 1/8" check ball.

So you drill a hole in the boss directly behind the brass plug. I used a 3.3 mm drill suitable for an M4-0.7 thread. (If you want to tap it to a no. 6-32 thread, you can use a #35 drill bit) Don't drill any deeper than about 7 mm or you'll drill away the seat for the check ball on the other side. There'll be a smaller hole which leads to behind the plug. Use something small enough in diameter to slip through this hole and tap out the brass plug. Once you've gotten the plug out, you can tap the access hole you made on the boss and put a set screw in to plug it again. This is already done in the photo. I used an M4-0.7 x 4mm set screw. (You could also use a 6-32 x 5/32" set screw)

You can see the seat for the check ball. The silver 1/8" check ball was what was missing. You need to acquire one from an outside source. Tap the check ball on the seat a bunch of times to burnish the seat and help it seat well. Then you drop the check ball in and press the brass plug back in to just flush (don't push it in deeper than flush or the check ball won't have room to move). Done. The accelerator pump will now work normally.

[alfajuj]

The old Harley Veglia tach didn't work and the speedometer was in miles, but I need km/h, so I used these replica Smiths clocks. They're from India, you can find tons of these dirt cheap on ebay. I figured that the 1960's Sportsters used Smiths tachometers, so these fit in with the theme of the bike. I adapted the brackets that came with the gauges to work with the original Harley cups. The challenge was to make the tachometer work. The replica tach was mechanical (chronometric), but I need electronic. So I got one of those small diameter universal electronic tachometers from J&P. I took the guts out of the Smiths gauge, and adapted the electronic one to use the housing, face, and needle from the Smiths. I didn't photograph the process, but as you might imagine, it took a lot of doing, but it works fine.



It's the guts from this one that are hidden inside the Smiths housing.
It's kinda cool, when you switch on the ignition, the tach needle sweeps from zero to maximum and back again.

[alfajuj]

Here she is! Ready to hit the road!
All the blood, sweat, and tears have been worth it in the end!

In spirit, she's a late 60's XLCH.

[rockman96]

Man, that is clean! Awesome job!

[ExplodingCoffinEmporium]

Looks great Alfajuj, thanks for sharing