Hey! Just wondering if anyone has run these Mercury 300x outboards on their boats? I am considering purchasing a 2003 34 cc that has a pair of them with 450 hours or so. These are the X's not XS's. They seem pretty badass from what I have read so far, but are they
reliable? Would they handle long idle periods? Are they close to needing a rebuild at this many hours as hopped up as they are? FYI, from what I read, straight from Mercury Racing, they are stroked V6's, with ported & polished heads, better exhaust and computer control with 7k rpm limit.
Thanks!

I owned a 2004 on a 22 Velocity. They don't seem to like long idles and can foul plugs. Great engines on light single or twin sport boats and cats and are "reliable" by old two stroke high performance definition when compared to the 2.5 ROS. They do smoke quite a bit too.

They are good motors but yes with 450 hrs I would say a rebuild in the near future would be a good idea. They make good power but burn a lot of fuel and as noted some didn't idle that well. Are they 20" midsections with sportmaster lower units? That would make them a little more desirable for resale.

Had a buddy w/one on a 120 mph tunnel boat.

He bought it new.

Was one of the first, true, hi perf 2 strokes that did everything well.
Idled, shifted, tons of low/mid range, and I don’t remember the smoke.

They were non/pre direct injected so they would smoke more than them.

They do have a checkered past which I’m sure depends on upkeep and preventative maintenance.

His was bad ass though and I loved it.

He showed me his smart craft gauges and it showed running 1600 gls of gas through it w/o being apart.

I think Stock rev limit is 6700.

I have a pair on the back of our 28 Skater and they run like a scalded dog! Tilt them up when idling and docking and they will not smoke as much on startup.

What he said

MDS

I will be looking for two in the near future.

I should add … I probably have ~ 300 hours on mine - also on a 28 Skater.

As far as idling, I've idled mine for over a mile a bunch of times - no issues. Mine run fantastic.

MDS