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Discussion Starter #1
What can you tell me about the 1972 ironhead Sportster?

I have a guy here wants to trade me a running one in decent shape (bone stock) for all my T500 stuff (approximatley $2500 to $3500 in value). He says it has the alloy rims and drum brakes all around, 1000cc motor, and that is all I know.

I have been looking for one to build an HD cafe racer (not an XLCR replica...my own thing).

What should I look for to be bad and expensive to replace?

What is good about it?

what is it really worth?
 

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the 72 uses bastard cylinders ..... not the end of the world

the very first thing you want to look at is under the engine and make sure it's clean so you can tell if there are any cracks in the transmission area. they are notorious for blowing the drive side lower corner out. many have been repaired.

if it's running and sounds like a wheat thresher... you can probably expect plenty to be wrong internally and it could be anything

nothing about them is expensive to fix or get parts for

I hate HD generators, well most any motorcycle or automotive generator but especially the HD genny

which is why I do not run them

my 68 XLCH has a permanent magnet alternator running off the end of the crankshaft

but if it really is bone stock and decent.... it would probably be much wiser to keep the rolling chassis that way and plug the engine into some other non-overweight multiple hinged chassis that actually handles

it will go into a featherbed for sure and I have some mount plates that somebody else did, they are pretty much junk but will at least will get the IH into the fbed


hard to say what it's worth without you know what
 

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Geeto,
The T 500 frame is kind of like a Featherbed. I wonder if the XL motor would fit in it? I really hate the stock sportster frame with the cast lugs and such. I would try to find any other frame that the motor might fit in.

Ken
 

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Discussion Starter #4
what do they use in flat track when they run Ironhead sportys? or is that strictly xr750/1000 territory?

I'll get pics when I can.
 

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first good step is weld up the hugely oversize intake ports


they have the same size intake ports as a 74 inch shovel

raising the port floor and making it D shaped dramatically increases flow and max HP potential

and also makes them much easier to tune

long rod to stroke ratio along with huge intake ports equals dog

this is why the Thunderheads worked so very well on them

would you like to see some very detailed pix of a near mint pair?
 

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Discussion Starter #6
yes I would. was doing online research for thunderheads, couldn't find much except to say that there may be as few as 300 pairs in existance and that they work really well but need machine work to fit.

If I get it I think I will use the stock frame, not building a race bike here, just a good cafe posuer bike. If I wanted something reliable or rideable I would have stuck to japanese and found an xs650.

as for the T500 frame it is more like a 3/4 commando than a manx frame. the TR500s used manx style frames but those were racebikes.
 

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the stock frame is woefully pitiful and overweight too boot

again.... if it really is a nice stock original..... keep the chassis that way and put the engine in something useful or you will hate it











ports 36mm valves at an included angle of 72ish degrees for a semi-hemi

the only machine work required is clearancing the cylinder fins for the reangled pushrod tubes
 

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Discussion Starter #8
are those yours hack? they are super pretty. I don't even want to ask if they are for sale because I could tell you right now I can't afford them (right now anyway, although I covet them....).

I have heard about the frames being a nightmare, cast lugs front and back with too small tubing throughout. A buddy has a really nice hardtail chassis for one but I am hesitant to do a hardtail IH chopper, seems everybody makes choppers out of them.
 

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Discussion Starter #9
BTW, is there a way to run dual carbs on these motors? like one for each cylinder, not a hsared dual carby manifold.
 

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I sold that pair and the pair I have left are not for sale



well I do have an independent runner manifold that will bolt up stock





they are somewhat restrictive but fine for hot street/mild road race

easy to cut away a bit of the partition on the carb end and find more topend

then there is the option of running two front or two rear heads

or you could run two spread bore progressive carbs like I have on mine
 

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and you can even run high pipes on the left if you want to bad enough.... I don't guess you can just order them from a catalog or online though

these sound really fine



I've no idea why the pix in a couple of my albums are distorted
 

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Discussion Starter #12
first of all...totally awseome spool wheel on that dual carb IH, is that an old 60's magnesium dragster (halibrand) front wheel?

That dual carb manifold, did you make it? I may have to talk to you some more about it if I get the sporty. what carbs do you run on that? I have a set of monster mukuni VMs (42mm?) I might want to put to good use. I am hesitant to look into the two front or two rear head idea bcause I don't like the idea of an exhaust pipe running right near one of the other carbs. On the other hand, two fronts could give me that nice vincent look

I would love to stick the motor in a norton frame but it is not in the budget.
 

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yeah and it's set up for dual discs.... I have them put back

I think they are American Racing Wheels and they are very light magnesium

the manifold shown is available, scarce but they can be had

I'd surely not recommend a 42mm on it either single or IR

36 is plenty and 38 could prove a bit too much

If I were going to two head one.... it would be two rears with forward facing carbs because you know how much I seem to love working bags of snakes out of carbs

this is one setup I made



another a bit more complex including one off manifold

 

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pair of 36's
 
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