The 600 and 900 Kawasakis of this era must have their valve shims checked at 8,000 miles, and every 8,000 miles after. First time around, we’d look to be changing at least 13 or 14 shims, due to the valves stretching and the gaps closing up, leading to lumpy running and a rough idle.
This clean and tidy Kwak, as it happened, was fine and its engine servicing had been done up to date. However, we road tested it after the shim check and found the rear brake was absolutely solid and sticking, so stripped, cleaned and put new seals in it; the bike was also steering like a bus, with notchy headstock bearings (a standard problem on these because water drives up off the front mudguard) so we swapped those while we were at it.
Another roadtest and we still weren’t happy; this time the fuelling was out (the owner had put a can on it). From memory we recalled some lean running issues with this model back in the day, off idle and in normal riding conditions, so we richened it right up off the bottom and bingo! A lovely bike, nice to ride too.