Hi, I have a KZ400 D3 (1976) and these days it has a rubbing noise on the top of the engine, on both sides. Maybe it was there before and I didn't know about it. It is a noise that increases not in volume but in tone with the engine rpm, as if something was not properly lubricated, but that is just my intuition.
Any initial ideas? The truth is that the bike works wonderfully, if I ignore the noise.
(1976) Kawasaki KZ400-D3. All original, but: electronic reg/rec (Oregon Motorcycle Parts), new handlebar controls (w/ PASS/HORN/lights switch, LED dash lights (superbrightleds.com), Dynatek coil (3ohm), MAC mufflers, HEL brake hoses, rubber fork boots, 4.00 rear tyre (Dunlop K70), chromed chainguard