TOPIC:

is it possible to use spark plug wires for a car on a motorcycle? i was wanting to replace the plug wires on the 74 Z1, i was in the auto store the other day and seen accel 8mm plug wires and was wondering if i could use them on the 900. It still has the stock coils with screw in wires.

I asked a similar question about 8 mm vs.7 mm plug wires. I got no reply here but when I was ordering my plug wires from Z1 Enterprises I asked the salesman what was the difference and which wires were correct for my KZ1000. He said (to poorly paraphrase)that the 7 mm wires would provide a better spark because the voltage is forced through a smaller aperture. Much like forcing water through a garden hose (smaller) as opposed to a fire hose (larger) A certain amount of voltage going through a smaller wire will have much more intensity than a larger one.
I got the 7mm wires and they work great.

I use 8.8mm accel wires on my bike. Here's the thing though, they were made for KZ-1000's, they have NO resistor for noise suppression (radio noise). Car wires do to eliminate interference to the AM/FM radio etc. The parts store may sell racing wires that don't? I was wondering myself since you can buy 8 of the best accel wires for about the same price as 4 made for motorcycle wires. So I don't the answer to your question myself. I'd like to find out though. The other thing I noticed is that the wires on my bike are stainless steel braided. Most spark plug wires seem to be made of some weird material these days that you would not be able to solder (my coils do not have detachable wires and must be spliced).
In any case if you can find wires without supression they should be good.

as for the 7mm vs 8mm debate. Bigger is better, but supression would probably lose you a lot more spark than you would gain by increasing size. The reason bigger wires are better is due to the way electricity flows. It's called eddy currents IIRC. Electricity flows in a circular motion around the outside of the wire core so more surface area is better. I'm not an engineer but that's how it was explained to me. I'm also told that more thin strands are preferable to less thick strands or a solid wire. Course, I could have been fed a load of crap who knows