Woa, hold your check mark there cowboy. The interference generated by the spark plug IS RF and the spark plug wires are antennas that radiate the RF and ferrite on the spark plug wires will have an effect on reducing the noise. It may not be practical but it will snuff out noise to the CB radio if done right.
First you have to look at the equipment making the noise. The rise and or fall time of the spark determines what range of frequencies with a 1 microsecond rise time making RF noise up to the 1MHz range, a 100 nanosecond rise time making up to 10MHz of noise, a 10 nanosecond rise time up to 100MHz and 1 nanosecond rise time up to 1GHz. The rise time of the motorcycle ignition system is at least at least a 38 nanosecond to reach the CB band to cause and radiate lots of noise there.
The intensity of the spark partially determines the level of interference and the length of exposed spark plug wires and how they are shielded by vehicle body parts have a huge impact on how far away the noise is picked up and what frequency range is most affected. Motorcycles usually have very short spark plug wires that favor higher frequencies above CB but they are out in the open with little to shield them.
The most common snap on ferrite cores out there are a #43 mix and clamping that over a spark plug wire equates to only 1 turn through the core providing very little choking effect at CB frequencies. Every time you run the wire through a ferrite core the inductance goes up by 4X, or about the same as using 4 snap on ferrites in series. I know from experience it takes at least 3 turns through a #43 mix ferrite clamp on to have a good effect at reducing RF noise in the VHF band (150MHz) but still does very little at CB frequencies.
If you were to get a ferrite clamp on with a more appropriate mix at CB frequencies like a #31, then installing about 20 of these over the spark plug wires would have a very noticeable effect on reducing the spark plug noise and possibly up to about 20dB of reduction, which is similar to store bought 1:1 balun chokes made for coax. Or wrapping about 4 or 5 turns of spark plug wire through one #31 mix ferrite would work about the same.
The problems are now, will all this ferrite fit on my spark plug wires and what is this going to do to the spark? There will be some degradation of the spark but probably no more than going to resistor type wiring or plugs. The resistor wires or plugs slow down the rise time of the spark and intensity among other things and contribute to reducing the radiated noise.
In the end if it is the spark plugs making all the noise in the CB, and there are resistor plugs or wires already in use and they are in good shape, the only real practical way to reduce the noise would be to shield the spark plug wires with hollow braid over the entire run of exposed wire. This works really well but in some cases the added capacitance of the ignition system output to ground will delay the spark enough to require adjusting the timing a little. Not a big deal and on the few vehicles I've done this on the engine performance did not appear to be affected.
Bottom line of my post here is spark plug noise is RF and ferrite will have an effect on reducing it if you can accommodate the ferrite. Hope the OP can run some tests and determine exactly what is causing the noise so the proper fix can be done.
prcguy