I ride Honda 2005 CB900F and I've been having a few issues with with gear changes, running (rough), and and a bit of power loss on occasions. This started happening around august/september last year, so I booked it in for it's full 12,000k service even though i had only ridden 9,500 k's. Since then i've ridden 2,000k's since. There was no noticeable difference after the service performance-wise, with the exception of the brakes being tighter, and the clutch a hell of a lot tighter. The running rough and gear changes seems to be linked, and have gotten worse. The running rough part feels as if i'm engine breaking at the same time. When this occurs, my gear changes become very clunky, especially from first to second. It's not so bad doing down hill, if it's on flat, and especially up hill, it is very noticeable. Even selecting first gear from neutral makes a loud clunk. Previously I could usually take off in first and fly through all the gears without barely noticing the transition through the gear changes. Now I have to hold the clutch in for 3 to 4 times longer, until i can fell it's ok to disengage and slip into gear. At the start, I noticed a pattern with the symptoms. When I filled up the bike with petrol, it would be fine. At around 120k's into the tank, it would start getting the above mentioned problems. About 15 to 20 k's before the fuel light would come on (180+ k's) , it would start running fine again. I've had a few false neutrals in higher gears aswell. At the start I thought it was because I had tapped into gear just a touch before the clutch had fully engaged, but not it happens too often if I try high speed acceleration. And in the last month i've notice a subtle power loss around the 3,000 rpm mark. At first i thought i might have closed the throttle slightly, but it's happened a few more times,and it only last a second. I don't know anything about bikes, and I was fine with sticking to the service schedule, but the next one is 3,000k's away, and I don't want to keep wasting my money getting it serviced earlier, especially if it wont fix he problems. I'm finally living at a place with a car port, so I picked up my bike stand, gave the chain the most thorough clean of it's life with some kero. Checked all liquid levels, the air filter, and took out the spark plugs to see if there was any signs of... whatever They didn't look too good. Especially number 1. I'm planning on changing the oil and filter, even though i had a look at the oil and it was clean; because i read in a post that different oils can affect gear changing and clunking etc, and I loosened the clutch cable a bit. But i'm not sure if I need to replace the spark plugs, or if they can just be cleaned with a brush. They were a pain to get to, so i'd rather leave them out if i'm going to replace them. When i first got my bike i would use either BP Ultimate or Mobile 8000, but in the past 4 months it's always been BP from the same store location. I might try changing store aswell. And suggestions on what could be causing these problems or things to try would be greatly appreciate. Keep in mind, i only have the toolkit from the bike. Also, how tight should spark plugs be when i put them back in? When i was trying to take them out it took a huge amount of force to loosen them, and i wondering if that was from the soot, or it they need to be very very tight. But on a good note, hopefully me chain will stay cleaning for longer now that i discovered this deposit around the ...sprocket cover? Cheers!