1996 Mariner 115 carb screws????

wycough · #1 July 8th, 2007, 05:29 PM

I have a 1996 Mariner 115 that has the top two carbs with the adjustments screws. After a soft seat, how far out should they be turned out?

Thanks

Silvertip · #2 July 8th, 2007, 06:05 PM

There is no exact setting but you can start at 1-1/4 turn. The "fine" adjustment must be made with the engine in the water -- not on muffs as there is no back pressure. Starting with the top carb, note the position of the screwdriver slot. Then turn the screw IN in 1/8 turn increments, pausing after each adjustment to let the engine stabilize. At some point the engine will begin to gag and tend to stall. Note that position. Now turn it in the opposite direction, again in 1/8 increments until the engine stalls. Happiness is somewhere in between the two stall points. Repeat on the other carbs. This process requires some patience and a good ear.

wycough · #3 July 8th, 2007, 11:10 PM

Does the "idle screw" only adjust the idle or is that used in setting the timing? I did not adjust the timing stop screws. But, I did have to adjust the idle screw to get the idle down after getting the throttle cable correctly positioned.

Silvertip · #4 July 9th, 2007, 02:15 AM

There are lots of screws to fiddle with but the idle timing and wide open throttle timing are two to keep your fingers off of unless you know what your are doing. The idle speed screw (only one of those) sets the idle rpm. Each carb has an idle mixture screw. Those normally have a spring under the head to keep them from working loose. On the 115 two of the carbs will not have idle mixture screws as two cylinders are killed at idle.

wycough · #5 July 9th, 2007, 09:45 AM

I need to put a picture of the idle screw up to make sure I have the right one. The idle screw adjustment is the one I need. The idle timing and the wide open timing both have jam nuts on them, right? One at the top of the arm and one at the bottom of the arm.

The idle rpm adjustment screw is in the middle with the spring and white plastic, right?

My air/fuel mixture brass screws are set at 1 1/4 turns out. And I'm at 1200 rpm's on the muffs. I believe it should drop about 300 rpm's when in the water.