Motorcycle Repair: 89 kx125, clutch side, kawasaki dealer

Question
Hello.
I have a 1989 Kawasaki KX125.
I just had the top end redone.
I put the bike back together, and started
it up for the first time.
It ran great, but after that, each time I started it, the engine would race (idle) faster and faster. The carb is set right, the throttle is not sticking, so I had no idea what was going on.
I asked a mechanic at the Kawasaki dealer, and he said it most likely is worn crankshaft seals in the lower end of the engine. He said they were probably worn, and the enging was sucking in air, causing the bike to run lean, and the engine to idle extremely fast.
I have never heard of this, but then again, I am no expert.
Do you think he gave me the right advice?
Thanks.

Answer
Arthur, He told you right,It sounds like the seals have got hard or are leaking .If the engine smokes more than usual it would be the seal leaking on the clutch side,If the engine idles fast ,acts like in is going to run away ,or doesn't come back to a idle very fast? It is the seal on the mag side. Hope this helps. Good luck.Try me again.Glen