Optimax spark plugs

[Jbooth]

In the hunt for the missing top end revs on my engine, today I decided to change the plugs in my 225 Opti.
I pulled the old ones, (managed to get them without splitting the bottom cowl!) and they were in pretty bad shape. At the time I noticed one of them had fouled up and the gap was bridged.
After putting the new ones in (gapped them to 0.8mm) I had a closer look at the old ones. I noticed one of them is about 8mm longer than the rest! someone has put odd plugs in the engine.
I presume the 5-800 revs I've been missing at WOT could be explained by this?

[paintman]

Only if the missing revs have been restored!

But the gap being bridged (whiskered) would stop that plug sparking - had similar on a Ford Granada V6 car I owned in the 80s which suddenly started running rough.
Not unusual either on old Seagulls & British 2-stroke motorbikes!

[diver 1]

Not as bad as that, but the last dealer to who had serviced my Opti 225 for the previous owner appeared to have installed the wrong plugs too. There's a sticker on the side of the engine even saying the correct plug! They're not cheap. I think I paid £68 for 6 genuine NGK plugs but well worth it. Made a difference straight away

[Jbooth]

I paid £77 for a set of 6 NGKs. Not cheap for sure, but hopefully will solve the mystery!

[roger dodge]

Just a thought ? Not sure if it is possible. Lexus cars along with many newer cars these days have bugs with some exotic metal electrodes that only get changed every 100,000 miles or something g like . Yes they cost but not having to worry about them for years might be worth it ?

[Searider]

Originally Posted by roger dodge

Just a thought ? Not sure if it is possible. Lexus cars along with many newer cars these days have bugs with some exotic metal electrodes that only get changed every 100,000 miles or something g like . Yes they cost but not having to worry about them for years might be worth it ?

Yes, those are the ones - "iridium" tops - can be up to £20 each but iirc recommended to be changed every 200hrs on an outboard.

[Jbooth]

Tested the boat yesterday, with new plugs installed and we’re back in business. 55mph- revving to 5500. Thank goodness for that.