Terry, you got an ironhead too, right? When you get around to working on this, have a look at the combustion chambers compared to your evo. You will see how much work harley did between the two for surprisingly little result. And i certainly dont understand what is so adult about trying to go fast on a farm
tractor. Fun yes, adult no.
Which model Sportster head combustion chambers are you talking about Sean? The combustion chambers on my early Evo are the same as my iron head's, whereas the later (2004 and onwards) "Buell" heads had "bathtub" chambers. which, with higher compression pistons, better cam profiles, fuel injection etc, produced way more power than mine. If mine had a 2004 and onwards engine, I'd be looking at more than 25% power increase over my old 1994 Evo.
Your point makes me laugh though, when I think that Honda spent a huge amount of money on the F2, changing the combustion chamber shape to accommodate bigger valves, changed the valve angles and used heavy duty springs and a lumpier cam to gain a whole 4 BHP power increase? And all that wonderful engineering made the F2 the most fragile of all CB750's. Not a total failure like the VF750 etc, but if you want to compare apples with apples, you don't need to look past Honda for embarrassing failures.
As far as going fast goes, the legendary XR750 was based on the sportster engine, and The XR-750 went on to win the most races in the history of American Motorcyclist Association (AMA) racing. Not too bad for a "Tractor".........