Just one final comment, all gas engines in the states are leaned out to the max in order to pass the exhaust emmission regulations, Harley Davidson engines are no exception. The way a Harley carbureter works is that the idle mixture is controlled by the slow running jet which is adjusted by a small screw at the bottom of the carb (the plug can be removed by drilling it outon sealed carbs - did mine) however when the engine speeds up the mixture is set by the main jets, two different systems. It may be in this case that the idle mixture needle valve is not set correctly causing the engine to run lean at idle therefore overheating and causing the pipes to glow red and when riding the main jets setting the correct mixture and the glow dissappears.
I have read on this forum many ways of, screw in the mixture screw, back it off so many turns, then fiddle with it, methods of setting the idle mixture. The correct way is either on an exhaust gas analyzer or if like me you havn't got one of these laying around there is a small tool available made by Gunsen called a color tune (not sure if these are available in the states, I found one on ebay UK for about 20 pounds sterling) these are actually a glass top spark plug, just warm up the engine and replace one of the spark plugs with the color tune, restart the engine and you can see exactly what is happening in the combustion chamber. As you adjust the mixture screw the color of the combustion gases will change. Just follow the instructions and you can set the mixture spot on, all in five minutes and cut out all the guess work. Make sure you get the right one for a Harley, 12mm, and one that is designed for a motorcylce engine.
Also check for manifold seal leaks prior to adjusting the mixture.

 

thanks for the schooling on a c.v. carb but he is talking about a fuel injected bike.

 

A side question on hot pipes, possibly related to an07 recall question I asked the other day. So, my Nightster is new and the Rush pipes with 2" baffles are on, but the new air cleaner won't go on until my 1,000 mi. service. EFI re-mapping will be done then too. I've noticed the muffler gets super hot--not red and glowing, but hot. Once the re-mapping/air cleaner mod is finished, should it cool off some? Are there performance issues I should be on the look out for during the first 1K? Thanks!

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