Right spark plugs for trolling with a Yamaha F40?

[Serious Business]

I have a 2001 Yamaha F40 (4 stroke) and used the original spark plugs for two years. I put on about 230 hours both trolling and WOT, mostly slow trolling. Spring 2003, I had the motor serviced and had them change the plugs. They put in NGK DPR6EA-9 replacement plugs which are specified in the manual. After about 120 hours of operation identical to the first two years, these plugs were fouled with carbon---the motor would start and then immediately die. Fortunately, it was the last day of a two-week fishing trip---and it was raining. OK to quit. I took the motor back to the repair shop and the mechanic said I should have told him I would be trolling with the F40 since that required a hotter burning spark plug. He put in NGK 2887 DPR5EA-9. He said that should solve the carbon build-up problem. Is this correct? I don't understand how I could use the original plugs for two years without a hitch and only get half the use out of the new plugs.

 

[FishermanEd]

Re: Right spark plugs for trolling with a Yamaha F40?

The mechanic did you a favor. Don't worry about why your plugs did not foul previously. Too many factors. Just be glad you now have a hotter plug.<br />I had the same problem with my 90 Yamaha. I just went with a hotter plug for the same reasons as you. I troll a lot and the plugs were not burning off the oil, etc.

 

[LubeDude]

Re: Right spark plugs for trolling with a Yamaha F40?

Just thought Id drop a note!<br /><br />The hotter plugs are going to solve both of your problems temporarily, but i personally feel you may do your engines damage in the long run, espesially if you are running at WOT for long periods of time before trolling and the run home! The hotter plugs can cause a piston failure with extended use at WOT! If this isnt an issue you will probably be ok! <br /><br />I would recomend you going to a synthetic blend or full synthetic oil, you will not have the fouling problem with the cooler plugs and practically NO carbon buildup! Use full synthetic lower unit oil also as it will do a better job for you in the long run!!

 

[JB]

Re: Right spark plugs for trolling with a Yamaha F40?

Reminder, LubeDude and others.<br /><br />The F40 is a carbureted 4 stroke engine.

 

[LubeDude]

Re: Right spark plugs for trolling with a Yamaha F40?

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