Since this is my first post, a short introduction;
Bought a Diversion XJ 600 (1998) a week ago as a bike to learn how to do maintenance and repairs. It needed some work (oil, spark plugs, naked conversion), but ran good when I bought it.
Since yesterday there is a problem with - I think - the clutch. It started once I changed the oil and oil filter (20W40): I start the bike in neutral, but when I kick it into 1st gear, the bike shuts off with a small 'jolt' forward. Bike is in 1st gear.
Put the (not running) bike into neutral, put it on the middle stand so the back wheel is lifted from the ground and retried. Bike started with no problem, pulled the clutch lever, kicked it into 1st gear and I saw the rear wheel turn immediately (with me still having the clutch handle pulled). This is weird

Some things I checked;
- Adjusted the clutch lever (did some new wiring on the front since I'm converting the bike to naked) and thought I'd maybe pulled the clutch cable or something), but nothing changed; bike jumps forward into 1st gear
- Took the clutch plates out and checked the thickness; they're all within spec (3.1mm, manual says between 2.9 and 3.1mm)
- Inside of the clutch looks really clean, no foreign objects, metal grains or whatever, just clean metal parts.
- Shifted to 1st, then to 2nd gear to see if the wheel would behave the same; it did. Turning speed immediately went faster after shifting up to 2nd gear.
There is no clutch rattle, bike starts without problems, but I'm sitting here typing this message with a big question mark above my head. I have no idea what could have caused this.
If anyone has an idea of what to check or what to do, that would be of great help! Always glad to learn new things
Thanks in advance
Rowie100