CBR 900 RRV Misfire....
So....after its winter hibernation, I broke my Blade out, for Spring/Summer. It's a 97 (Dec 97!) RRV and I've owned it (second owner) for about 6-7 years. It's not "mint', but its a really tidy, useable Blade.
I got it out in my Workshop and, whilst i left it ticking over and went up to my office, a "friend" of mine walked in and rev'd the nuts off it. I was pissed....but just pushed him off it and went for a quick "rod test" to see how it was after its annual rest!!
At low rev's, it started to misfire and needed a bit more throttle applied to get it going/to get it to pick up. I nursed it back to the shop and it was quite lumpy at idle, but then seemed a bit better.
I thought I should start by checking plugs (replaced about 2 years back with only 1000 miles) and they look decent. I am tempted to change the coils, but at £370 ($500!) for the pair, if I'm not right, its a waste of cash. I also noticed when it was rough at idle, that it almost seemed to "knock" a bit at the bottom...but am not sure.
Any ideas of symptoms when the coils start to degrade? Is it low end misfires? Anyone on here have good used coils i could buy? Found some on eBay in the UK, but they won't guarantee them (like buying any used engine components....sellers claim ridiculous low miles etc!!).
Thoughts on any damage possibly caused by the dick of a friend rev'ing an unloaded engine like he did?
Thanks in advance