SparkPlug's

[Ghostshad]

How often should You change your sparkplug's ? My boat runs real good , 70 miles a hour runs smooth . I don't run it like that ,  i was trying to get it good & Hot to clean the inside of the motor. But it don't idle good , it die's sitting still & idling , dies while trying to run it on the trailor . Will sparkplug's cause that ?  GodBless & Thanks

[J Francho]

I put new ones in after burning off the fogging oil, each spring.  Those old ones get shrink wrapped, and put into the repair kit, in case one gets fouled while on the water.  Be sure you properly gap the new ones to spec.

[Al Wolbach]

27 minutes ago, J Francho said:

I put new ones in after burning off the fogging oil, each spring.  Those old ones get shrink wrapped, and put into the repair kit, in case one gets fouled while on the water.  Be sure you properly gap the new ones to spec.

 

Good advice. I replace my spark plugs anytime the engine seems a little sluggish, much like you described, usually about once a year. I also use my boat year round. I would suggest running a mixture of Seafoam all the time, or at least occasionally to help keep your engine clean. This can prevent/delay the problem you described. It is also a good idea to run you boat wide open(full throttle) for 60 seconds or so just before putting it on the trailer to help keep the engine clean.

[Way2slow]

There is about a 99% probability the synchronization is on the carbs and linkage off and the idle mixture is off.  When I get done with one, you can sit a full glass of water on top of the engine and it won't shake out.  When it comes to sync'ing the carbs and the linkage, close is not good enough.  It's a painstaking task to adjust, check, adjust again, check again and keep doing this until perfect.

 

You can help the idle some idling it up some.  Just don't get it too high where it bangs the gears when you shift.   If you look on top of the motor you will see a black plastic shaft piece with a knurled knob on it.  Turning that knurled knob adjust the idle speed by increasing the idle timing.  It has no affect on WOT timing, that's another adjustment, so you don't have to worry about it changing on you.   

Also, this has to be done after the motor has been warmed up and is sitting in the lake trimmed down so it's sitting fairly level, vertical with the lake level.  You CAN NOT adjust the idle on a hose or in a tank.  It must have the proper back pressure on it to set the idle speed.

Also, do not use the linkage stop screw that rest against the block to adjust the idle.  Turning that throws the whole synchronization off on everything, and can make the whole thing worse.

 

On a stock motor, I usually run spark plugs about 100 hours.  The set in my 225 ficht have been in it for about five years because I haven't been using it that much.

If you fog your motor for the winter, then do like J Francho.  Run the motor in the spring to burn the fogging oil out and then replace the plugs.  I have on more than one occasion had fogging oil to leave a residue that caused a miss fire if the plugs are left in after burning it out.

[Ghostshad]

What is Fogging oil ?

[J Francho]

It's for winterizing the boat.  It's a heavy oil you spray into the intake until the motor stalls.  Prevents corrosion on the internals.

[tander]

One thing to check on is if you are running the right recommended plug. My boat was having starting problems. I looked in the manual and found out that I was running a different plug than recommended. I changed out to the right plug and it made a huge difference. When all else fails, read the instructions !!!