Classic Steel

GP’s Classic Steel #93: 85 YZ490

Comments (3)
  1. Awesome write up on the 490. I just picked one up with the head mod and ohlins simons suspension. Can’t wait to finish restoring it. Keep up the great work.

  2. A great read, and for the most part i agree; it vibrated and had average suspension, but as a 20yr old just racing at club level in AUS, we found the need for more power. Easily fixed with a forged Weisco 80though oversize piston, shaved head for more compression and boyesen reeds – the beasts absolutley motored and we had big grins every track day.

    Fit a smaller rear sprocket and they became lethal high speed weapons on the fire road little mountains around where we lived. Nothing like holding it on the back wheel until it revved out in 4th. More power never hurts.

    At 50+, perhaps a different story now, but I still crave one for old times sake.

  3. There was nothing more fun to ride than these beasts. No one wanted to get stuck behind you for they were sure to be pummeled by baby head sized roost.
    Not having the dough to make suspension upgrades we just tinkered with oil weights and spring spacers, twisted the throttle and held on tight.

    As far as engines went the Weisco big bore over size combined with an aggressive port job, shaved head and some re-jetting seemed to clear up most issues, but the magic sauce was the Klotz octane booster combined with Belray MC1 eliminated the pinging and meant they were bullet proof from a reliability perspective.

    They were the golden age when more power was just enough. If you have never ridden one, well you missed out on an eye-opening experience

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