Carb cover....whats with it?

[Roughneck1860]

There a plastic cover over the mouth of the carb on my 30hp Mariner. It says do not operate motor wiht out cover in place. Is this because it will let too much air in and cause the motor to run lean? I thought maybe it was for dirt but theres no filter element inside or anything. Can anyone help me out?

Thanks
Tim

 

[dpatterson]

Re: Carb cover....whats with it?

I could be wrong so don't quote me.

My exp is from my jetski's which the pastic cover is called a flame arrestor that prevents fire from entering the engine area (too much) in the event of a back fire.

Some of these also help control the flow of air depending on the design (atleast on ski's)

 

[j_martin]

Re: Carb cover....whats with it?

You can lean it out to the point of burning pistons if the carbs are exposed to a fast moving airstream stuffing them.

It is a flame arrestor, and when a 2 cycle "sneezes", it's shooting flame out a carb.

hope it helps
John

 

[Roughneck1860]

Re: Carb cover....whats with it?

Thanks for the replies. Here's what I was hoping. I'm looking to get a bit more out of my motor. I checked the parts list and the only difference between it and the 40hp is the carb and reed assembly. The exhaust and exhaust ports are the same on each motor. I'm going through a divorce right now and am tapped for $$$ or I'd switch up those parts. I'm thinking if I go up one or two jet sizes might help a bit. I know I'll need more air to go with it and was planning on drilling a few holes in the cover to allow for better /more air flow. I'll think even clean up the intake and exhuast ports to help with that. I've done alot with 4 strokes and ATV's as far as jetting and exhaust goes but not with 2 strokes. Does this sound about right?

Thanks
Tim

 

[JB]

Re: Carb cover....whats with it?

Carburetor throats and venturis are designed and jetted to "flow" up to a certain amount of air and still draw a proper amount of fuel. If the air flow exceeds this level the mix will be leaner. . .dangerous for 2 strokes unless the high speed jet is adjustable, which it isn't in most modern outboards. Badly adjusted adjustable jets have killed many an outboard.

It seems, then, that going to a larger jet would be the thing to do, but how much larger? Guessing how much larger is rolling the dice with the life of the engine.

My advice? Do what the maker says. . .leave it alone.