November 4, 2010 7:55 AM PDT
First of all there is very little that you can do to really deal with the heat of the rear cylinder, it is one of the design faults with a V-twin. The closed loop EFI system makes a very good attempt at dynamically adjusting fuel and spark fire to maintain the correct exhaust proportion via the O2 sensor which equates to temp on each jug. However the current O2 sensors have a very narrow band of expectable performance and once the engine performance goes beyond that due to heat there is little that can be done. The heat causes a lean mixture and the EFI can only compensate so much. The limits are mandated by the software design to limit pollution.
Now having said that, Thunder Max is a good after market performance system and the offer O2 sensors with a wider performance window. However keep in mind, this is a system and to reap the entire benefit you need to install the entire system.........close to $1000. The over all benefit is marginal when it comes to heat. Where this really shines is when you start adding performance goodies. No matter what you add, the software will adjust to give you the best performance and do it dynamically.
A cheap alternative to all of this, is to run synthetic oil. Most synthetic oils will allow the engine to run cooler under normal usage.