Question on Merc 2.4 jetting

[motorcyclefanatic]

I purchased a Hydrostream Valero recently with a mid-80's 2.4 Merc V6. The boat seems to run fine, if not a little fat in the mid-range.

I decided to pull the carbs and do a cleaning and see what was inside. It has WH22 carbs which run 74 & 76 mains and 46 idle jets stock. I found the mains had been been bumped up to 80 & 82. All the idle jets were 48. The vent jets were all stock.

The plugs all looked a little sooty, but I'm not sure how long they'd been in there. I don't have any history on the motor. It also seemed to be a little on the thirsty side. The oil injection has been removed, pre-mix @ 40:1.

I wondering what the consensus is for returning the motor to stock jetting. I don't want to seize it or hole a piston. BTW, I'm running in Florida, so no offset to the stock jetting is called for.

Thanks, John

 

[fastjeff]

If you're running those surface gap plugs, you're flying blind. I suggest you put in in a set of Autolite 303s (or equivalent) which will give you a plug reading. Once you've got her set, puts the surface gap plugs back in.

You read the jetting on the 303s by the following method: Run her hard, then shut her down fast as you dare and pull the plugs. If they are light brown or tan you're on the money. Sooty black is too rich, and stark white is "Look Out!" time.

Jeff