HI there hoping for some help here . I bought a 1993 XJ 600s diversion , starts and ticks over fine . but when it warms up while riding it starts getting very temperamental starts running as if its missing, , lack of power between 2 and 4000 revs and vibrates. as soon as it hits 4000 revs and over it seems to smooth out . any help would be appreciated 

craig

What on earth are you doing riding at 2-4000rpm. The bike will hate you, any middleweight will get the arse at those rpm for more than a passing glance. It may be highlighting a weak plug or some carb balance but to be honest. Get the bugger up to 5-6k in town and let her rip out of it, its not a car, she needs revs. 5k on a light throttle is fine. Wide open at 3k is nasty.

If your trying to pull along in 4th or (God forbid) 5th gear at 2k then there's no wonder the bloody thing rattles, As above open it's throat a bit 3500 to 4000k minimum in high gears 1st and 2nd you will get away with but any higher gear will protest.