In order for the MoCo to meet the ever-more-stringent EPA requirements on motorcycles, without going to a catalytic converter, they put the O2 sensors in, enlarged the mufflers for more "freer" flowing exhaust, but yet could be baffled enough to keep the noise down, and leaned out the fuel mixture. I've never had the noticeable heat on the rear cylinder because I had the true duals put on the bike before I took delivery of it. I'm running the standard "84" map on the SERT right now, until I get it dyno'd at the 1k service. So I'm not sure what the f/a mixture is, but I'm sure it's not at the factory stock level.
Red