[smiley=soapbox.gif] Here is what is going on! [smiley=soapbox.gif]
Harley used the solenoid closed left exhaust muffler system in 2006 also. The intent was to direct the exhaust from both cylinders through the right catalyst muffler for emissions purposes, period. It clearly choked off the exhaust for the majority of your riding. The left side muffler solenoid would only open up at RPMs in excess of 4000, then it would act like the exhaust of 2005's and earlier. Obviously the 2006s would benefit from disabling the solenoid and leaving it open, or simply replace the mufflers with good flowing pieces. Really, you gotta get that chit of the bike.
For 2007, again as a concession to the EPA, Harley upped the ante and leaned out the Air/Fuel ratio even further to reduce emissions. This is what is really causing the heat issues with the 2007 bikes. It is not just with the 110's, the 96's have the same problem. You absolutely have to undo the emissions concessions that the MOCO has agreed to and get the bike on a pre-2007 standard as soon as you get it. For the longevity of the motor, it has to be done.
The rear cylinder on a Harley engine has always run hotter, simply because it does not get the same cooling air. The rear cylinder is in direct alignment with the front; it does not get a direct blast of cold air as the front cylinder does, and in fact gets pre-heated air from the front cylinder, hence the problem. In the old FLH days, Harley used to alter the cam timing between the front and rear cylinders to compensate for the naturally hotter rear cylinder. The valve timing on the rear cylinder was milder, to generate less heat. This worked to some degree, and was necessary with the use of carbs. But with fuel injection, you had the ability to adjust the timing and fuel for each cylinder individually. Check you SERT maps between the front and rear cylinders and you will see what I mean. But with the latest EPA concession, the MOCO has gone too far. Motors are getting hurt, and bad.
It would be naive to simply take the stance, well; I have an extended warranty so the problem is on them. It is actually your problem. You bought an inherently defective piece of chit. The motors are self-destructing. You can play these games on a water-cooled bike, but not on an air-cooled motor. You are flirting with disaster. I blame Harley MOCO for this. They should have tested the EPA operating parameters they were agreeing to before they released the bikes for the 2007 model year. These motors will not hold up. You have to take corrective action immediately. Heat is your major enemy on an air-cooled bike, and the MOCO just handed you all a stick of dynamite with a very short fuse. Ignore the issue, and the problem will definitely present itself; directly or indirectly, the problem is yours. Harley did the same crap with their cam tensioning issues on the Twin Cam. This chit is a major no-no. You do not treat your loyal customers this way.
What do you do with your 2007? Regardless as to whether you want more performance or not, you have to get the stock factory exhaust off. You have to eliminate the solenoid system on the left muffler, even on a stock bike. If you want more performance, here is your opportunity to improve the exhaust. Then you need to richen the Air/Fuel mixture, whether its with a SERT, Power Commander, Thunderrmax, etc. to improve performance and cool things down. This in essence will have undone Harley MOCO's EPA concessions and will have cooled things down, improved performance, gas mileage, and above all, significantly lengthened the life of your motor. If you want to add performance of top of that, do the air cleaners, custom dual exhaust, cams, etc. But, even on a stock bike, you have got to get rid of the heat.
My personal friend is a machinist, and we rebuild a lot of motors on a regular basis. The stock Harley had enough problems with the rear cylinder operating at higher temperatures even before this EPA Bull Chit. Now it is a disaster. Often what happens is that guys will overheat the rear cylinder, and the rings will not seat. Compression is down, the cylinder walls are scored, and there is significant blow-down because the rings did not seat. The rear cylinder loses compression and uses oil; seen it too many times. Time will tell. Personally, I would do the SERT, exhaust, and air cleaner changes immediately on purchase, prior to doing any damage to the motor. You cannot undo the rear cylinder damage once it has occurred. You have to prevent it up front.
I will make a prediction, that with the MOCO's willingness to cow-tow to the Feds, that the change to water-cooling will happen much quicker than you think. Otherwise the motors will not hold up. This is a major turning point here. The Harley air-cooled motor will suffer the same fate that Volkswagens air-cooled Beetle suffered in the 1970's; it died. Get your air cooled Harley while you can, immediately correct what Harley has done to them, and hold on to it. You have an instant classic Harley, one that will shortly be going the way of the dinosaurs. Get your vintage piece now and enjoy it. The MOCO is in the process of destroying its legend, all in the name of progress.