I have a 1984 Yamaha 225dx it seems to slip in almost all gears and sometimes 4th doesn't work at all.. I don't know much about these shaft drives if anyone could help with some knowhow it would be much appreciated
The repair manual says to check the clutch adjustment and if that's not it to take it apart and check for worn plates and springs.
with the clutch adjustment you need to loosen the nut and then turn the tension screw counter clockwise till you feel resistance then back it off 1/8 turn and lock the nut down while holding the screw in place. I know it sounds backwards but that is how it works if that doesn't work for you let me know I have a spare set of plates that are still in good useable condition.