Honda Fourtrax 300

Been tinkering with a Honda Fourtrax 300 that my FIL has. I got it running fairly good after I removed the carb and cleaned it. When it is cold it needs to be choked for a good while to keep it running and it will start to run away with the choke on. When it is kinda warm it will idle nice and slow but will miss once every 5 or 6 fires. It misses like you were to shut the key of. When I was working on the carb I couldn't get the motor to fire and found out there was no spark. After turning over the motor some more I got an erratic spark and then a consistent one. When the motor is good and warm the low idle is not low any more. The motor begins to climb in rpms to the point when you put it in gear the thing jumps. Also when running the four wheeler down the road it will run perfectly at half throttle. At slightly above idle it will start to buck a little like you were turning the key off and immediately turning it back on. At full throttle it has a knocking noise but not a hard knock kinda half way between a knock and a hiss.

What would be causing the increase in idle as the motor got hotter?
Would a bad ignition modual explain the complete miss at idle and the lunging at lowerer rpms on the road?
How would I test the modual?
Thanks for your guys help!

Forgot to add that it is like an '88 model.

(quoted from post at 03:07:11 04/10/17) Forgot to add that it is like an '88 model.

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Classic signs of running lean. Carb problems or an intake air leak. Clean carb again and make sure it is seated with no air leak.
The knocking you are hearing can be pre=ignition.
Don't continue to run in this condition!

Running lean was the first thing to come to my mind too. I suspect a vacuum leak rather than a carb problem. Either way it's a classic lean running symptom.

Thanks, I was outside and fiddling with it and adjusted the carb and she is purring like a kitten now. Still has the pre-ignition under full throttle but is running much nicer. I will back the idle screw out a little more and see if that gets better. Much appreciated.

I agree with others, too lean idle mixture or vacuum leak.

Any adjustment on the idle mix?

If that is a slide type carb, raising the needle a couple notches helps with the cold natured running.

How is the wiring going to the handle bar kill switch? Or any other wiring that may be grounding the ignition, intermittent short or corroded/wet ignition switch or kill switch.

Pull the valve cover for a look, valves out of adjustment can cause the rpm fluctuations you are describing.