Yamaha YZ490

Yamaha introduced the YZ 490 in 1982, after a solid run with the YZ465.

Problems

Sadly, the 490 was heavier than the 465, nowhere near as reliable, horribly difficult to start (hot or cold), came with a grim suspension, vibrated enough to bring blisters to your hands and was impossible to jet.

If you jetted it rich enough to keep this dog from seizing, it would blubber, puke, foul plugs and produce no power. If you jetted it to run strong, it would invariably seize. It came with air leaks, a wandering ignition, gimpy motor mounts and the worst case of Yamahop at high speeds since the original DT-1. Yamaha issued a mountain of service bulletins to try to fix the problems. None of them worked.