1996 cbr900rr
Ok here's my issue, stored my bike correctly for the winter, stabil and all, went to start it and it was firing on numbers 1,2 & 4 but not number 3. Was getting gas to all 4 carbs, all clean and distributing gas evenly. Pulled plugs, the misfiring cylinder plug was soaked, obviously no spark. Cleaned it and then tested for spark and got spark. Put it back together and it ran better/all 4 cylinders firing.

Now here is my issue, the number 2 cylinder stopped firing and numbers 1,3 & 4 are firing fine. Pulled plugs again/cleaned them put it back together and it ran great. Rode for a hour or so and headed home. Got close to home and number 3 cylinder stopped firing again.

I'm thinking the coil for number 2 & 3 is on it's way out. Would I be correct in this thinking?

Plug wires look fine from outside and all other wiring looks ok.

Cliff notes, number 3 not firing, then firing, then number 2 not firing, then firing, then number 3 not firing again. Bad coil pack?

 

Pretty much spot on i think .... 2 and 3 are run off the same coil .
If it were mine i'd check voltage to the coil wires if that's ok i'd swap the coils over if the leads will reach... always mark up which goes where before pulling them all apart. If it starts to dick around on 1 and 4
you've found the offender. If not check the carbs arn't flooding ... and most definately throw the plugs out and put new ones in ... nowadays this is one of the most neglected items neing that the motors are soooo
reliable today.

Keep us posted

 

What is a PITA is that it is either hit or miss, once the coil stops working on one of the cylinders, the carb still puts gas to that cylinder and then floods that plug. So therefore there is no easy way to test the coil unless I get lucky enough to have the meter on it when it happens. I am believing that it happens for enough of a cycle that it fouls one of those plugs and then will start firing again, however since the plug has been fouled with gas, I will not get any spark at that point out of the wet plug to burn the raw fuel although the coil is firing.

I'm going to swap the coils and see if that does the trick in determining the issue.

 

Putting a meter on the coil wires ie the yellow blue / black white feed wires to the coil will determine whether the coil pack is getting 12v supply from the ignitor. This will be constant.
Also the charge of fuel and air in the cylinder is not completely soaking but a fine mist and considering the others are running the temperature in the cylinder and head will be quite high so an amount of evaporation will occur anyway.
The flooding part i would check is in the carbs (needle jet) which controls the shut off of fuel. If stood for a while its possible particles in the fuel can sit on the needle seat and stop the needle closing the carb to new fuel and making it prone to overfilling. This has happened countless times in my ownership of the steel frame cbr 6 and 900 blade as they only get seasonal use.