Honda SOHC ignition systems are really simple in design and easy to fault find if you go about it in the correct way. If you know about cars, then you'll probably be fine (unless of course they are electronic and computer controlled!)
Start with the fact there is no spark on any of the four cylinders. This means the plugs, caps, leads, coils and points are OK as any fault here would cause only two plugs to fail. These bikes use the \"wasted spark\" system, so there are two coils and points and cylinders 1+4 and 2+3 fire together. Luckily (for Honda) on one of these cylinders is on the compression stroke at the time. This saves having four sets of everything (or a distributor).
The fault must be either the 12V feed to the points, or the earth connection from the points plate to the engine. Check that you have 12V on the points (I use an old headlamp bulb soldered onto two lengths of wire). As the points open, the lamp should light up. If not, check back along the wiring loom for the feed (usually a black wire).
If the points aren't opening at all it will have the same effect (never seen that on both sets of points though)
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Steve
