"RB" wrote in message
...
If I decide to buy a used outboard, is a dyno run at full power the best
way
of assuring myself the engine is OK?

It would tell you that the engine is currently working reasonably well. It
wouldn't give you any assurance of how long it would continue to work. The
engine could still have cooling problems, leaks, etc.

If I wanted a seller to have a dyno run done on a candidate engine, I
assume
I would be obligated to pay the associated costs. Is this normally the
case? I would like to set it up to where I wouldn't pay costs if the
engine
failed the dyno run.

I have no idea where you would have a dyno test done on an outboard, or how
much it would cost. If I was selling a motor, and a buyer said that he
wanted a dyno run, I would not agree unless the buyer was covering all the
costs associated with the test including transportation of the motor. I
certainly wouldn't agree to paying the cost in the event of a failure unless
it was clearly defined what "fail" means.

If it is a 200 HP motor, and according to the dyno it delivered 199 Hp, is
that "failing"?

This situation isn't much different than getting a survey on a boat. In
this case, the buyer usually pays the cost of the survey. If he doesn't
like the results of the survey for any reason he can abort the sale, but he
still has to pay for the survey.

Rod