Merc inline 6 carb jet

[tbjtib]

Hi,I have a 1980 inline 6 merc 90 hp. I recently rebuilt the carbs and installed new jets.I used what the manual called for (.070 for main jet at sea level)I then heard that increasing jet size is common in old mercs to keep from burning a piston.Any thoughts on this? should Ileave alone or open jet?

 

[what200]

Re: Merc inline 6 carb jet

I decided to take the same advice on my 1500 after hearing many stories of melted #3 pistons. In fact I bumped up 2 sizes in the middle carb, but this is more for piece of mind.<br /><br />Your 90 is fairly detuned for a inline 6 so it should be more tolerant of lean mixtures.<br />You could try to jet up one size, run it for little while and then pull the plugs to make sure you don't have too much carbon build up.