I have a 1997 royal star deluxe. Not sure if I have a problem or not. I haven’t had this bike real long so I am not familiar with how it is supposed to run. Now for what I am experiencing. Through the gears and especially in 4th and overdrive I feel a vibration on exceleration, especially when you lug it alittle. At first I thought I was running to high of gear but even when running in 5 th it vibrates almost like a miss. I pulled the plugs and they are all a nice even tan exactly the same. The one thing that concerns me is when I used a inferred on start pointing at the base of the exhaust port the front 2 cylinders are running about 125 deg’s cooler than the back cylinders. Is that normal with these motors? Also what are the correct spark plugs for this motor? Any help would be great