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Old 08-07-2008, 09:22 AM
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Default Best Performance Mods for an Ironhead?

What are the best performance mods for these engines and how much total power can you get out of these?

Thanks.
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Old 08-07-2008, 08:14 PM
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It depends on how much money you want to spend, but a good ignition system, Andrews cams, and an S&S Super E carb are a good start. There's a site that I can't remember right now that shows how the guy building the motor got something like 170 hp out of an Ironhead, but it was strictly for racing. I'd want to keep the bike reliable enough to ride it every day, so minor mods like the ones listed above are my preferences.
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Old 08-08-2008, 01:12 AM
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I would say to daily use streetbike, HEADWORK ( new valves and porting), 10,5 CR pistons, Electronic ignition,good carb (size about 38-40mm mikuni dellorto) S&S will do as well as CV Keihin from evo. Factory P-cams. Theese mods give you 70-90hp from rear wheel.
If you are planing to go up from that you need to keep mind that after this bike isn't for daily use ( my opinion )
Then you need do more modifications: clutch (XR mod), thrust bearing to front spoket, better brakes.
Here is sample 130hp ironhead (street bike)
http://www.hdforums.com/forum/pictur...&pictureid=685
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Last edited by sepixlh; 08-08-2008 at 01:17 AM.. Reason: added link
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Old 08-08-2008, 07:45 AM
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Thanks all. The motor is in a very well built rigid frame with a fat tire on the back, good brakes etc. It's set up to take what ever I can throw at it. I'm contemplating working this engine or just swaping it out for a buell motor....... Any thoughts?

By the way, sick turbo set up.
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Old 08-08-2008, 06:31 PM
jtmon75 jtmon75 is offline
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Default iron head mods

mario, my 75 sporty has been bored .030 over s&s 13/16 stroker kit ,super E shorty carb, andrews #5 cams,heads have been completely rebuilt,slightly massaged and milled,drag pipes and stock ignition.high torque starter and compression releases installed. this bike has tons of power and torque.when i roll the throtle and the motor gets into its power range the rpm's rise very quickly when i crack the throtle hard i better be hanging on!!! oh and by the way i can ride all day(if my butt can take it).to install the stroker kit make sure you have somebody that really knows what they are doing with the cylinders.
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Old 08-08-2008, 09:55 PM
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It's been said that you can get 80-85hp out of a street Ironhead and still have some reliability......Stroker flywheels, stroker cylinders or base plates, dual plug heads, 10.5:1 or better compression, aftermarket trap door, aftermarket trans gears and shafts, aftermarket starter (unless you got an iron leg to kick-start) and a machinist as a good friend.....With a stock bore 61" pistons and 4-5/8" stroke you'll have 74"....Five-inch stroke flywheels are out there but not a good choice for street with the piston speeds. Going bigger than a 3-3/16" bore means boring the cases which would not be a good choice for street riding. Using factory cylinders with a stroker kit requires mods to the cylinder oil drains...Plus there is the heat issue with the faster piston speeds.
Or you can stick with stock bore/stroke and go with a set of cams, carb, ignition, head porting, front sprocket change and get 60-70hp......Don't quote my numbers because there are Ironhead builders out there that know more than I ever will!
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Old 08-09-2008, 06:56 AM
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My motor has been bored out .20 over, running 10:1 pistons, 1 3/4 drags, stock carb with edelbrock air cleaner, and i feel than I can outrun just about any vtwin out there. When I open up the trottle and go from 1st to 2nd, the bike nearly throws me off the back and almost raises the front wheel off the ground. You did not say what year it was, if its late 60-early 70's the first upgrade you will need to do before making it go faster is making it stop better. Front disc brakes are a must have.
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Old 08-09-2008, 08:21 PM
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You can go mild to wild. Sporster Bob and his avitar is wild (5" stroker I assume) I run a 5X3 5/8.
If you go to the AHDRA website you can find wild to mild Ironhead stuff fairly cheap in their swapmeet section. Theres a lot of great performance stuff out there. Have fun!
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Old 08-10-2008, 10:50 AM
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Thanks for the replies all. So far I'm sold on the performance aspect of it. Now, $$$.... How much are we talking to get this up to 80hp / 70tq range? I know everyone is different but a good guesstimate would help. By the way, it's a 76 sporty driveline...Thanks.

Click the image to open in full size.
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Last edited by Mario77746; 08-10-2008 at 11:06 AM..
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Old 08-11-2008, 01:37 AM
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Quote:
Originally Posted by SportsterBob View Post
aftermarket trap door, aftermarket trans gears and shafts,
I personally don't recom aftermarket trap door, it's much cheaper and easier to replace busted trap door than engine cases... seen that. Gear set is good choise , same time you can switch to close ratio gearing.
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Old 08-11-2008, 01:37 AM
 
 
 
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