TOPIC:

I have a deal that I cant figure out. I have a Z1 that runs. When I ohm the secondary side of the coils I get an open reading going from one wire to the other on the same coil. The other pair shows 27 ohms when it shows 24 as right. When I ohm the spark plug ends {original} on the wires I get an open reading on half of them. I realise what its telling me but why does the bike run ? I know how to fix it but I just cant figure it out. Anybody got any thoughts on this. When I say runs, its rideable but not very strong. Valves have been adjusted, carbs balanced, compression is good, primary sides of coils show 4 and 4.1 ohms, points ign, gap set , static timed for now

If the coils are the original ones that came with the bike they may or have been broken down due to heat or vibration in their operating environment. The spark plug covers/caps may also have been damaged and can be replaced (they have a resistor to retard Electromagnetic interference.

From your discription I'd say you have a weak spark and need to have the coils checked at the bike shop to see if that's the problem. I have heard good things about the Dyna ignition coils so that might be your next purchase.

mtkawboy wrote:

When I ohm the spark plug ends {original} on the wires I get an open reading on half of them. I realise what its telling me but why does the bike run ?

If you ohm across the plug wires I believe you are ohming the high voltage secondary winding. It is possible you could have an open in the winding which would read open with a meter, but the high voltage would jump it when it sparks and still deliver enough spark to the plugs. The plugs air gaps are also open circuits. If there was an open in a winding, it would look like another air gap in series with the two spark plug gaps and the total voltage would divide across all three... which might be enough spark to run, but maybe not real well.

That sounds exactly like what I have going on bountyhunter. It runs but not too well. I have Dyna green coils & wires on my other bike and I know they are good but this is an original paint 73 Z1 and I prefer to have it remain stock looking. I have another Z with a 1000 motor that Ill check and see if I can use that stuff. Thanks for the help, this thing was messing with my mind