DF 250 WOT issue

[Gerardi]

Hi. New here. I have a 2013 DF 250. Two summers ago we mounted it on a brand new 24 foot centre console. For a whole season it ran well, easily reaching 6000 rpm and could even go beyond (reaching 6200 rpm) without a problem and with an obvious grunt at that level. This past season (last summer) the motor still worked perfectly fine throughout the whole range, absolutely no starting issues or any other form of flaw in the engine performance (no pinking, spluttering, knocking, hesitation etc) except that at WOT it is not going beyond 5500 or 5700. Nothing has been added or changed in the boat and the hull (which had only been in the water for a few weeks in the first season was cleaned just the same, antifouling slightly sanding and recoated. Might be my impression but at WOT the engine does not sound as if it has the grunt it seemed to have initially. Never had any warning signs on and serviced each year by dealer mechanic in my garage (I believe only thing that was not changed in the last service were plugs). Engine has no more than 200 hrs. Currently boat is in storage. Any suggestions will be appreciated.

[Moonlighter]

Bad spark plug, they are due to be replaced.

If they were taken out and checked, or replaced recently, a plug not put back in or gapped right, or a plug lead not put back on securely....

It does happen.....wouldnt be the first brand new spark plug that was bad, or was dropped before being put in.....

If it has hit 200 hrs it is also due to have valve clearances checked and if necessary, adjusted. Important job that should NOT be neglected.

[Gerardi]

Thanks for your help.