Re: 1998 Johnson 150 Ficht Fast Strike
Welcome to iboats.<br /><br />The soot is actually normal. The direct injected motors seem to do that. One thing they've done to help minimize the negative effects of that is to "index" the sparkplugs. The sparkplugs are marked on the porcelin outside where the gap is open (or 180 degrees from where the hook part attaches to the body of the plug), then installed so that the open area faces the intake ports. This helps blow some soot away each time air is taken in. With the hook in the way, carbon can build-up and foul the plug.<br /><br />You can do the indexing yourself. The sparkplugs need to be marked so you can see where the openings are when the plugs are installed. That just takes a Magic Marker on the porcelin. You can usually mix the sparkplugs around to find where they are in proper position when tight. It takes a bit of trial and error. It's best if the marks face the intake ports (to the outside), but if they're 90 degrees off (straight up or down) it's no big deal.<br /><br />At full throttle you should be able to max-out the recommended RPMs. You don't need to run there all the time, but you overwork the motor if those RPMs can't be reached. The proper pitched propeller is the key to that. If the prop pitch is too high, you won't reach the top RPMs. That would be like driving thru town in overdrive which isn't good for any motor.
