I have a 2003 883 sportster, I have available 'take off' cylinders, heads and pistons from a 2003 Ultra Classic. Can I bolt on without any machining?

 

Not even close. Different in every respect.

The biggest you can go as a bolt-on is a 1275 kit.

Going any bigger than that requires a full tear down, to bore the cases and/or install a stroker crank. But even doing that, you don't use Twin Cam parts, you use special aftermarket parts designed for the Sportster platform. Too many things are different about the Twin Cam platform, everything from the cylinder stud pattern to the spigot size to the cylinder height to the compression height, and more. Those pieces simply do not fit the Sportster motor, and making them fit isn't practical.

 

Here is your other 88 question with answers

https://www.hdforums.com/forum/sport...ter-883-a.html

 

OP; Give 'er a try & let us know how it works out...

JK, don't even try...best to swap entire motor, if you're look'n for more cu/in. Have you looked into the 1250 Hammer kits for Sporty's?

 

You guys are entertaining this ? Read his username......