Rear subframe modifications

I started by cutting the back of the rear subframe off and welding on a new hoop to give a nice clean rounded "butt" to the bike.

New hoop welded on
New hoop welded on

I realized there was a problem with the new hoop when I mocked up a seat with some carpet foam. I figured a standard size café/brat seat would look pretty good, so I went with ~2" of foam, but it looked horrible. The angle of the rear subframe on the LTD model of a KZ550 is steep to support a two-up "King and Queen" seat, not the style I was looking for.

Here is the ugly seat, with the tire mocked up for positioning. The ramp is longer than the flat section... yuck.

I spent some time thinking about the seat frame, mocking up different seat options with cardboard, etc. After a while, I got so frustrated with making no progress I cut off the hoop, chopped the rest of the rear seat frame off, and welded the hoop back on. this gave me a much more aggressive look, and the proportions really started to come together.

If life gives you subframe lemons, chop them right out and don't worry about 'em.

Along with the subframe work, I grinded off the rest of the frame tabs I wasn't going to use and bent the old rear shock mount supports around the new hoop to keep the original lines of the bike. Happy with the progress so far.