Help please,

My son's 96 425 magnum 4-stroke has a slight miss at low rpm's and fouls plugs, some smoke at high idle.

good gas, new air filter, new plugs. Any ideas?

Thanks

 

If the plug is oil fouling and your burning oil then you either have worn out rings or bad valve seals. If the engine has never been worked on it may be tired. The only simple thing I can think of is it's too rich at idle and if that's the case it will foul out plugs. What color is the smoke? if it's black then I'd say it's too rich if it's white your burning oil and need to rebuild if it get's to annoying for you

 

Try backing out the air screw a half or full turn for more air at idle and low throttle.

Jim