Re: miss at idling 1975 Rude 15 HP
I just had the carb rebuilt and evrything checked out ok.Had the motor out today and when it idles at low speed or just in neutral at has a miss.At high speed she runs fine.Does anyone know what could be wrong with it??? HELP!!!
My first comment is that if you had a professional rebuild the carb, he should have adjusted this before you paid. It should have been as smooth as he could get it, or if he couldn't get it smooth, he should have told you so and you and he could have discussed other causes of the roughness.
But that said, are you familiar with the knob on the front for rich-lean adjustment? I'm not sure what it's labeled on your engine, but it should be evident which way to turn it for richer vs. leaner.
Anyway, at idle - if possible in gear (under load), if not, in neutral - try adjusting that knob to get smoother idling. ASSUMING it's set somewhere in the middle now, try adjusting it in small increments, like 1/8 turn, toward the lean side. Wait a few seconds after every adjustment and try to determine if it's smoothing out at all. Try several small adjustments in that direction to the stop point before giving up if you don't hear a change. If you do hear a change - if it seemss to get better - try adjusting a few more steps until it quits getting better or gets worse. Then do the same thing in the other direction. What I have done is try to determine the sweet spot for idle, and it's often 1/2 way between the two spots rich and lean where the idle changes from smooth to rough.
If you do this in neutral, you might have to tweek it a little more (baby steps!) idling in gear because the load of the prop spinning in the water changes things a little. Also, sometimes the best adjustment for idling or trolling is not the best for wide open - and when you change from trolling to cruising, you might have to adjust the rich/lean knob. But you'll soon know where it runs best at each speed and it will be routine. Sometimes you won't have to mess with it because it runs OK at both idle and faster.
I hope that makes sense and helps. If it doesn't, there may be a different carb problem and/or an ignition problem.
