Join Date: Apr 2007
Location: Sherrard, Illinois, United States.
Issues are as follows
C1+C2 both shell out transmissions somewhere between 30k and 50k, luckily the newer trannies slip right in and are much tougher, no detachable subframe making them expensive to fix crash damage, warped brake rotors, can't bore out cylinders past 1mm, no rear ride height adjustments. In my opinion the C's are slightly more comfortable than the later bikes due to higher and narrower bars which reduce the weight on your wrists. C1's also have overly stiff suspensions for street use, C2's are a bit better. C's have more topend capability due to more aggressive intake cam and bigger ports.
E's have heavier steering but a little more frontend feedback and stability over the already very stable C's, Carburation is somewhat snatchy coming off of closed throttles especially at higher rpm's, lower but wider windshield over the C's, E1's have a tendency to break their frame on the left side on top of the frame in one of the bends
F's heavier but I have never heard of any real problems with them plus they have the cool braced swingarms and different front fairing stay instead of the one going up from frame like on the older bikes, carburation is fixed from the E's. E's and F's have better midrange than C's. The dual headlights are MUCH brighter than the C models single. The only common fault I've ever heard on ZX-9R's is the cam tensioner problems.
I got about 35k out of my first tranny in my C2, the cam chain tensioner went at about 25k. My front rotors lasted until around 40k. Other than those things it has been fine. Martian9r on this board has over 50k on his E1 with only the frame break problem and a seepy engine case, real weird issue he spread a thin coat of JB Weld on it and it quit seeping.
Also in your case since you're in the UK make sure you don't get one with a botched carb deicing system removal. I'm not sure if all UK bikes had them but I'm pretty sure some did, I'm also not sure if they actually helped the bike but you're cold humid air apparently can cause the carbs to ice up without the system which circulates warm coolant around the carbs.
Find a clean one of any vintage with low miles and enjoy riding one of the most capable all around motorcycles ever made. You can track day it, you can ride hard in the curves and you can throw soft bags on it and ride 500+ miles a day in relative comfort. If I had to replace mine I'd probably try to find an F model buy Heli-Bars, a Corbin seat, Double-Bubble windscreen, trasplant my suspension, engine and wheels and ride the hell out of it. I can't think of any current bikes that would fit the bill, they're either too uncomfortable, too heavy, don't handle or don't have enough power.