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Customizing your Iron Sportster

Making your Iron Sportster uniquely yours is a time-honored tradition. A Jap bike is like a Glock. You buy it an use the heck out of it. A Harley is like a .45 ACP. You can build it from scratch just the way you want. Or you can take a stock pistol and change it and try things until you get it the same way.


I've got 5 Iron Sportsters and a K-model. They are all unique and there are different things to love about them. None of them is a restoration that is "correct" to the exact way the factory built it. Some are radically customized. My 1980 show bike Kenny Puccio converted to a mono-shock. Then he slapped an aftermarket set of Thunderheads on it. Not Thunderheaders, the exhaust, but Thunderheads, the aluminum heads that make an Iron Sportster run like an Evo.

My 1977 daily driver I got pretty stock back in 1984. Since then I have put different fenders, different tanks, replaced the sprocket cover with a steel mount, converted it to the early model dry-clutch setup and made a clutch actuator so it would all work. I put footpegs on the frame, where they belong, and run it with a bicycle speedo.
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The first rule of customization is to think about things.


If you think 40-inch apehangers look cool, you should maybe find some old dude who ran them. He will tell you any handlebar that keeps your hands above you heart makes for some miserable riding. Then think about mounting them a little loose so you can yank them down for long trips.


Motorcycles are very good at killing their riders, so be sure you know what you are getting into. If you want some crazy-long front end, realize it might make the bike un-rideable. My buddy Wax went through 4 gas tanks since his front end would flop over and the only stop was the handlebar grip denting the tank.
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Factory engineers are not idiots. They designed the Iron Sportster as a high-performance machine. If you start hacking on rake or trail or ground clearance you could get in a world of hurt down the road.

The same deal with engines. The factory P-cams are a darn good cam. Sure, you can put it some radical grind that won't idle and only makes power in a narrow band at 6000 RPM, but that is not a lot of fun to drive. When I was a kid there were always some kids with more money than sense that would put too much carb on their motors or too hot a cam. Cams don't create power or the factory would use them. They just move power around, from the low end where you need it to come off a light, to the high end where you indeed can get a few more horsepower.


This great picture from NHRS shows four different cam grinds, from mild on the left to race grind on the right. The wider lump on the race grind means it will make more power at high RPM, but it sure won't idle or come off the line well. That is why they are race cams. They are intended to be used where you always have the engine near maximum RPM. The race cam has much higher lift. That means it will tear up the lifters, valve guides, and a lot of other stuff. 
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Also think about the ignition. Don't be fooled by claims that imply the stock ignition only fires ohhh, 85, maybe 90% of the time. A Iron Sportster ignition fires every single time until you increase cylinder pressures or raise the RPM limit. Only if you have some real problems will you need a hot coil. And everything is a tradeoff, so that hot coil will put more load on the wimpy Sportster generator.


There is a design flaw in the 1970 and later "cone motor" Sportsters. Because the Harley engineers put the points plate on its side, it causes a the flyweights to start egging out the pins.
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The weights hit the back of the plate, and then the 1/4-28 screw holding the flyweights and ignition cam breaks off, stranding you.



I didn't get why this happened until I took a servo-control class at Delta Tau Data Systems in Northridge CA. Talking about machine control, one of the teachers noted that is hard to close a servo loop when there is a constant acceleration on the system. In the case of the cone motor ignition flyweights, that constant acceleration is the acceleration of gravity.

That constant acceleration is why the flyweights pulsate, and egg out the pivot holes and finally break off the bolt. If you do run the mechanical points, be sure to pull the plate and look at the flyweights. Its easy to see them getting worn.
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Also, don't think the 1979 factory electronic ignition will solve this. It still uses the mechanical flyweights for advance.

So now you might want to customize your cone motor Iron Sportster with an electronic ignition. Most are not made for Iron Sportsters and don't have the 45 degrees advance needed. I had a Dyna on my 1979 and I burned a piston, probably since I set it up to idle nice, but it was not getting enough advance at speed.

My 1977 daily driver has a Crane HI-4 and that has a wire for a VOES switch you can ground so that the bike is getting enough timing change between idle and full RPM.

Rather than change the motor right away, think about seats and riding position and hiway bars. Don't forget the mirrors. You might think its cool to have a dental mirror as your mirror like the chopper guys in the 1970s. I got hit from behind in 1987 so I buy those long long touring bike mirrors so I can see what is behind me.

Of course, a major part of customization is paint color and scheme. I would buy take-off factory tanks on eBay for my Iron Sportsters. It takes some hacking, but you can make mounts for them. Then when you drive to work, people will ask "When did you get that gorgeous bike?" Paint is all most people see. That and maybe chrome.

One thing you might want to do is buy a V-Twin catalog, as well as a Custom Chrome catalog. I think JP cycles sends theirs out free.
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You can view most of them online if you are on a budget but have a fast internet connection. Still, there is something nice about a big thick paper catalog. You can sit in the garage with your buds looking it over and thinking about what you might try out.

Iron Sportsters engines are in everything from drag bikes to dirt trackers, to road racers. Some guys set them up with saddlebags to haul the groceries home. Others like to chop it down the bare minimum. The great thing is there is an analog continuum between all the extremes, and you can try out one extreme, or the other, and everything in between. Stick to the middle at first.

I great modern improvement is in the online forums. I like XLForum and I just started checking out a K-model forum. There are dozens to chose from as well as hot rod forums and forums for paint or welding or whatever.

As an engineer I can try out thing in a CAD (computer aided design) program, but most anyone could use IrfanView to make a Photoshop image of what they are considering. And don't forget, a pencil and some paper works great too, as does squinting your eyes as you imagine the changes you will make to your bike.

That is what customization is all about, making it your bike. I once listened to two bikers argue for two hours over the difference between customization and personalization. All that matters is that it is an expression of your spirit.
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The most recent post: Install Buco saddlebags

Install Buco saddlebags

Build custom struts to mount antique Buco saddlebags on an old Sportster.

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The most recent post: Voltage regulator bracket

Voltage regulator bracket

Mount a Voltpak style regulator on the end of a generator.

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The most recent post: 1972 Sportster exhaust

1972 Sportster exhaust

Mount an old stylish factory exhaust to make the bike quiet.

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