Are there any tricks or mods to get the HP over 100 while still maintaining a measure of reliability? Do they make larger jugs? Or is the only way to increase displacement on an Ironhead by stroking the motor which of course increases wear.

 

I dont know all of the tech stuff but what I was told by our Master Mechanic at our local dealer. But I bought an 48 Custom Sporty on ebay and I learned how to do wheelies in all 4 gears. Broke a gear shaft 4th of July and brought it home and stripped it down. OK That answered the question. Someone put 1340 jugs on borded out ? over, put a stroker kit in and high compression heads. Lenny (mechanic) said he caould not believed I rode it. It is aboiut a 1480 and screams. Well I gave it to my other half and He loves it. iIt is in the process of being rebuilt just the way I got it. I am not sure what it all means except my other half has had it up to 140mph and said it still had more. I am not sure how the 4 speed will handle all of that. I guess we will find out as we are going to the National Hog Rally in billings MT. with a few side trips so if it can handel 2500 mils plus I will be happy.

Penny

89 1200 Stock Sporty mine

84 Custom Sporty Bruce



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'48 Sporty. I thought the first sporty was built in the late '50s. The tranny is the weakest component in the Ironhead powerplant. So any go fast mods to the engine will tear the tranny apart unless you upgrade the tranny as well.

 

If you want over 100 hp out of a Sportster, then you'll probably need an XR750 engine. LOL! I've never heard of a 1000 putting out that much unless it was super or turbo charged, or ran NO2. I don't know what my '76 put out, since I would never dyno an ironhead... dyno's put a lot of stress on an engine! Those older designs just weren't made to handle that kind of abuse. Most race bikes that are run like that get rebuilt many times over a short period of time. The EVOs and TCs are built better, so they can handle dyno runs with minimal wear on the engine. What I do know is that my bike was a lot quicker than my current EVO, which puts out over 90 ft. lbs. of torque. I'm sure the light weight of the Sporty had a lot to do with it.

There's one thing that I tell everyone who buys a Harley for the first time, or wants to modify one for better performance... DO NOT worry about horsepower numbers. TORQUE is what you want to increase! Without the torque to put it to the ground, HP is worthless. If you look at a dyno run sheet, you will see that the best performing street bikes have a lot of torque, starting low at around 2000 rpm or less, and increasing from there with no flat spots or dips in the curve. The high HP numbers will never show until over 5252 rpm, which is where HP and torque will always be equal. Usually after that point, torque will start to drop off and HP will keep increasing. But, who rides their bike regularly at 5252 rpm and higher? Maybe in drag racing, but rarely on the street. For a good performing street bike, you want as much torque in the lower and mid range rpms, since most riding is done between 1500 and 4000 rpm.

There are two things that have the most affect on torque..... cam duration and exhaust choice. Of course, compression will affect torque and HP to a certain point, but for starters, concentrate on the first two items. For a cam, you want to get the a set with the lowest duration and highest lift you can use in your engine. Duration numbers below 240 degrees are best. Lift is limited to the type of head work that's been done. As for exhaust, the best overall performing systems for maximun torque are any 2-1 system. They will outperform just about anything else on the street. While they are hard to find for ironheads, they are available. Drags are OK if you do a lot of high rpm running, but still need baffles. Cycle Shack slipons are pretty good, too.

Hope this helps!

 

HI, well first we have the basic build up, then we have a moderate build, and then the all out , build up. I keep my strokers mid range as to keep the temps from climbing to high. The stock 4 spd trans is allright, but for added strenght i use a trok door. The heads are very important, have them done, larger valves, port and polish a must for high hp sportsters. Reliability can be a concern if your trying to run a drag tune on the street. The carb should be a concern, and have jetted corectly, for the build. Finaly the exhaust, is as important and very misunderstood, as most builders overlook this part. Drag pipes on the street, do NOT make the most of a street tune. Gearing can be changed, sproket size, etc, to gain low end tourqe. It really doesnt take a large stroke to make very good performance gains, keep it real, and you'll enjoy it more, better rideing, than wrenchin.

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