Help please with Mariner 15hp stroke carb

[Laundryman]

Engine works fine at revs but will not idle. Suspect blocked slow running jet? Removed carb, separated float chamber, located what i think is the main jet and blew it through, can't seem to find the slow running jet! I know its difficult to explain but can someone please guide me to where it is or offer an exploed view/diagram showing where. Unless you have a better idea, Thank you

 

[Laundryman]

Oooops! That should have said 4 stroke carb

 

[exfinnsailor]

Our small Mariner had the same problem .. The slow running jet is not in the float chamber .. I noticed it by accident .. Have a good look round the outside .. It was a brass colour .. I think all it does is let air through .. Ours is fine once cleaned ..

 

[Kawasaki]

Yes it sounds like the 'pilot' jet.
Same thing.

The jet is covered by a rubber plug.
Remove the float bowl.
Invert the carb and you will see the plug next to the main jet 'orifice'!

Nip the plug out to expose the jet.
Strip all jets and plugs you can find.
I poke them gently with a hair off a wire brush.
I also have a compressor with a fine nozzle attached to the air line and blow through all the holes I can find when cleaning carbs.
Take the carb body to your nearest motorbike fixer.
He will/ should have the same set up.
It's what they have to do all the time with mopeds and stuff like that.

If the pilot jet and passage is blocked she will never tick over properly.
Once on 'main jet' (usually after aboit 1/4 throttle the pilot jet is redundant) hence running ok at speed.

 

[Kawasaki]

The pilot air screw is usually on the outside.
The pilot jet is on the inside.
Taking the pilot air screw out and blowing/ cleaning the passage can sometimes help.
Rule of thumb for anyone adjusting a pilot air screw on a small carb be it outboard lawmower motorbike etc.
Screw in gently until resistance is felt then screw out for one and a half to two turns and that's it!

 

[tross]

"Screw in gently until resistance is felt then screw out for one and a half to two turns and that's it! "

Then when the unit has warmed up, unscrew it until it goes a bit lumpy and then back in until it smooths out again. This will give you a slightly rich mixture which will help prevent the unit from hesitating when you open the throttle.