New boat wrong plugs

[Sailor61]

Got a new boat last week with a 2004 Merc 150 XR6 classic. First two times out it was extremely hard to cold start. Bought a shop manual today so I could check little things and do routine maintenance, good thing I did. The boat had
Champion QL78YC plugs gapped @ .020, They were wet / oily but appeared new. The Manual called for NGK BPZ8HS-10 @ .040 which I bought and installed today. I couldn't cross reference the Champion plugs. Does anyone know if these were OK just improperly gapped? and could they cause damage?
Thanks for your help.

 

[DamianJP]

Re: New boat wrong plugs

Hey Sailor61

Check this out, that is the right equivalent ...
http://www.ngk.com/results_cross.asp?pid=QL78YC&x=61&y=9&seenCrossWarning=1


Not sure about the gap but will try and dig something up to see.

DamianJP

 

[ufm82]

Re: New boat wrong plugs

#1- This is my opinion but Champion plugs stink in Mercs. NGK seem to be the plugs of choice. Obviously your engine wants a traditional style plug- that is it has an arm and a center electrode.
#2- the gap could have been causing an issue as the smaller gap could result in a weaker spark since it isn't as hard to jump .020 versus .040. I know that Fords don't like it when their gaps are wrong (auto tech history) so Mercs could be just as fickle.


UFM82

 

[Sailor61]

Re: New boat wrong plugs

Thanks for the responses and cross reference. I feel better that they weren't completely wrong just not properly gapped, half of what they should have been. I put in a new set of NGK's @ .040 per the shop manual. Taking her to the lake tomorrow, hopefully she'll fire up easier. I'll let you know, thanks again!

 

[Dukedog]

Re: New boat wrong plugs

Just about all carb Merc/Mariners have their own litle "quirks" when it comes ta starting. You will "find" yours after a little experimenting. Give tha Champs tha "float" test and never look back..............

 

[Sailor61]

Re: New boat wrong plugs

Well the NGK @ .040 were the ticket. She fired up second key bump spit the obligatory 2 stroke puff then purred. Went out on an empty lake warmed everything up, had a 15 yo, 12 yo and me app. 500 lbs plus 25 gallons of fuel.

I picked up 200 rpms and saw 53mph on the gps @ 5200 rpm. I'm a happy camper! Got a new four blade arriving this week, for hole shot / skiing. Thanks guys.

Keith

 

[ufm82]

Re: New boat wrong plugs

What's your WOT range? 5200 seems on the lower end. It's good to hear the plugs made the difference- that's why most Merc guys will vote for NGKs- they work.

 

[Sailor61]

Re: New boat wrong plugs

My WOT range is 5000 - 5600. My 5200 was running heavy but not max. I would expect another 100 - 150 if I were running light. Also I'm going from a 15 5/8 21P Tempest 3 blade SS to a 14 1/4 19P Stiletto BP III 4 blade SS. I'll check the WOT RPM after changing the prop, hopefully pickup 100 - 200 rpm, if not I can exchange for a 17P.