Ride for a couple hours today. It doesn't do it when your wind out 4th and 5th gear. Only 1-3
I still say the main jet is too rich for your set up. The big question is why is it rich when other guys with a similar engine package use the same or larger jets???
Air filters, pipes and the type of fuel have the largest influence on the main jet size.
Change the pipe and silencer and take it for a test ride. Mix up some fresh NEW fuel and take it for a test ride. If it still misfires at the higher RPM in the lower gears lean it down 2 to 3 jet sizes and take it for a quick test ride. If it has a stock 87 reed valve and petals, it will often misfire at 7600 RPM with some porting schemes and exhaust systems.
Air filter oil as well as the age of filters especially foam filters can have a major influence on main jet size. Removing the air filter for a test run is not always a valid test for testing the restriction of the air filter. I done a lot of flow bench testing and many times an air box/intake system will flow more air with an air filter than without any filter. I have seen engines run richer on the dyno without a filter than with a filter. Unfortunately a lot of stuff that happens in an engine does not seem to fit what common sense dictates.
Different silencers can change the back pressure slightly, making the engine need a smaller main jet without affecting the power.
The inside of the stinger and muffler accumulates a very thin layer of carbon as the exhaust system accumulates miles on it. Over time this layer of carbon WILL AFFECT the exhaust flow and back pressure at the exhaust port. I have seen exhaust systems with less than 50 hours accumulate enough carbon inside the stinger to cause the engine to act very rich at wide open throttle while driving the engine into detonation with a rich misfire.
One of the most critical welds on the whole exhaust system is at the junction of the stinger and tail cone. There should not be ANY weld boogers protruding into the flow path where the flow area is at a minimum. One of the most critical areas of flow is at the junction of the stinger and tail cone. There should not be any mismatches in diameters as the flow goes from the tail cone to the stinger. There should not be any sudden changes in direction as the flow goes from the tail cone into the singer. These are areas that are overlooked and special attention must be given during the manufacturing of an exhaust system.
The above mentioned areas must be inspected and corrected especially if you are having trouble with piston seizures and or holes being burned in the top of your pistons or jetting being very temperamental. I have seen hundreds of engines with recurring piston overheating problems because the pipe manufacture was sloppy and in a hurry when making/designing/welding this critical junction of the stinger and tail cone.