Kawi2strokes.com Forum

It's not hard to do if you have the cylinder off and the piston removed. You just have to set up a dial indicator on the end of the rod while you pull it up and down, with its side play centered. I did mine a few years ago so I don't remember what I did to hold the indicator, but I'm sure it was just come clamps and maybe a scrap of aluminum. It was right at the max spec, so I rode it 4 or 5 more years and then promptly got it rebuilt when a snap ring in the transmission failed.

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If it surges, that's normal, upshift.

All stock seals are both labyrinth style, and rubber. Earliest H1 used a center seal that required crankcase pressure to hold the seal lips to their races, later models were constant positive spring pressure against their races. Consider that center seals have to work opposite directions as they operate, and use both side lip,sets to seal crank case pairs.

No matter the rubber seal type, to check both ends of the center seals, all 3 cylinders must be both vacuum, and pressure tested as a single unit.