Today my 23 was running like a top. Then all of a sudden it acts like it's running on 3 cylinders. Here is what I've done to try and resolve it:
* checked that the coils were all seated properly.
* checked that the fuel tank was getting air and breathing.
* All 4 cylinders are getting spark
* Replaced all 4 plugs
One interesting note,...I get no coil buzz when I turn the key to mag. But it starts right up with no problem. ??
It doesn't stall and actually idles fairly well. Fuel issue? Where do I start?
Pull the timer off and look in there. It may need a little clean up. Also, You may not know it yet, but you live very close to "The Coil Doctor" Brent Mize, right over in Reynoldsburg. It might be that the coils need some attention. Old wise man once said...90% of carburetor problems are electrical.
Thanks Dave! Yes, Brent did build my coils and they're fairly new but I might swap out another set that he also rebuilt to eliminate that. Funny quote!...although I don't know which I hate more,...tracking down an electric problem or a fuel problem ;)
Another thing... Did you accidentally bump the fuel enrichment knob, on the dash, with your knee? Too rich of a setting will cause a sudden change of performance.
I agree with Dave's advice but I wanted to address something you said namely ..."I get no coil buzz when I turn the key to mag". That is totally normal. Coils will only BUZZ when the key is in the BAT position. When running or starting on magneto coils do not buzz but just fire one time for each pulse out of the magneto when the coils are adjusted correctly. Welcome to the hobby.
If you get the engine running, try shorting to the head each spark plug while the engine is running. If you notice that on one spark plug there is no change, that is the cylinder which is not working. Try first swapping that coil with one of the others. Then check again. If that same cylinder is still not working, but all the others work, it is not your coil at fault. It could be in the wiring or the timer. Try replacing the spark plug on that cylinder. But if the cylinder to which you have moved the coil is now misfiring, you have a problem with the coil.
After you determine that all coils are firing and all sparkplugs are sparking, and it still runs rough, do a compression check. With a stock head near sea level the compression should be around 45 or 50 psi. on each cylinder. If so, the valves and rings are doing their job. All cylinders should be approximately the same compression and it will be less at higher altitudes.
The fuel enrichment nob could cause a rough idle and perhaps cause the plugs to foul if you are running too rich, but the symptoms are different than those for an ignition problem. If too rich the engine tends to lope, and if too lean at idle it slows down and when pulling the engine will cough and die.
Make sure that all of the plug wires both at the plugs and coming out of the coil box are tight and clean. Also check the Battery and mag connections on the coil box. Good Luck
Make sure the spark advance rod is not touching one of the wires on the timer.
What shape's the fuel tank in? Old original, or just plain old? They get cruddy inside sooner or later. That crud makes its way to the carb. Ask Steve Jelf. After weeks of fiddling around with his poor running issues, he broke down and put in a new fuel tank and I believe that was the end of the problem. So as I suggested to him, if you have a tank that you have no idea how old it is and if it isn't really nice and clean inside then bite the bullet and replace it. Yes, you can clean tanks, you can coat tanks, but sooner or later, you'll be tanked. On the side of the road.
Tim is correct. I spent weeks fighting crud from my old tank, but a loose baffle clunking around inside the tank clinched the deal for me. When I went to an auction in Iowa, I stopped at Birdhaven and picked up a new tank. No problems since.