Re: 1998 Johnson 250 Ocean Runner Timing Problem
You are green regarding this motor...it is obvious.
But, mekaz is right, the timing shown on the air silencer is 18* BTDC at WOT (wide open throttle) (5000 rpm).
Now there are various ways to achieve this adjustment. One way is to hang off the back of the boat on smooth waters, and set it at speed. I do this often. Another way is to disconnect the timer base linkage, start the motor with throttles at idle, and manually rotate the timerbase to the full stop position. Engine will race, but not bad, and you can set the timing that way.
Another way is to follow Joe Reeves timing method, which is done at starter cranking speed (engine never starts), and you have to disable Quick Start, and you have to set the timing back 4* from spec, as Joe says it will pick up when the engine is actually running.
I personally prefer the second method mentioned above. The idle timing should be around 4-6* ATDC in gear idling. That will give you about 750 rpm. And of course no more that 18* BTDC at 5000 rpm. Two different distinct timing settings.
Now, the details of this are in the OMC Factory manual. These settings are critical to the proper running of the engine, and accidentally setting the WOT timing too far advanced will kill your motor over time.
So, get a book (not seloc, not clymer), read up on timing and how to adjust, quit guessing at what you are doing, before you do some real damage.
If you are close to me in FL, I would be glad to set it up for you. PM me if interested.