Lots of guys write asking what year and model of Buell makes the best donor bike for a Mutant or any other custom. Here’s the basics to get you going. Most manufactures of custom Buell frames are made to mate with Evo style Buells 1991-2003. Some do carry frames that will work with 2003 and newer XB models, but they are less common and usually a little more expensive.

Should I go Fuel injected or carburated?
Buell tube frame models from 1996 to 1998, 1999-2002 M2 Cyclones
were equipped with carburetors and standard dual fire ignition systems.
1999-2002 X1 Lightning and the S3 Thunderbolt models were fuel injected. One of the biggest issues when building a custom chopper of any kind is hiding the wiring. Given that, you’ll want to minimize the amount of doodads on the bike that require power, switches as fuses. Fuel injection systems require a fair amount of wiring which is the reason why most guys opt for a good old fashion carburetor. If your donor is fuel injected have no fear…It’s pretty easy switch it over. All you need is a carburetor, a manifold, an ignition module and some fittings.

Which models have the best engines?
If horsepower is important to you, you’ll want a Buell donor with a Thunderstorm engine. The Thunderstorm engine made it’s debut in the 1998 limited production S1 White lightning. The high flow heads, 10:1 pistons, hi-performance cam, and hotter ignition had the Thunderstorm engine producing 100 plus horsepower right out of the box.
The Thunderstorm engine became standard in the 1999-2002 in all three models ( X1,S3,M2 ). So how do you know if the Buell your looking at has a Thunderstorm engine? The first thing to look at is the heads. All factory Thunderstorm engines came with black powder coated heads.

Front Ends
All 1996-1998 S1 and S2 as well as 1999-2002 X1 and S3 models came with the Showa inverted front ends. while all 1997-2003 M2 Buells came with the regular tube and slider forks you see on a stock Harley.
Both will work fine. It’s a matter of choice. Some like the modern aggressive sport bike look of inverted forks, while others like the old school look of a regular front end. Either way, both will work fine.

Wheels
All Buell models from 1996-2002 came with cast aluminium wheels. While most were powder coated to match the color scheme of the bike, some models like the 1997 S3 had polished aluminium instead. Not a big deal but something to consider.