Topic: No spark at the plugs?

[toycollector10]

Three weeks ago I washed and detailed my CB750 K0 prior to an upcoming show. After cleaning and washing it down I towelled it off then checked the integrity of the electrics and carbs by starting it up and running it for about 30 seconds. No problems.

Then I put it away in the back of the garage.

Today I go to start it. No joy. Plenty of gas in the tank. Spark at the points but nothing at the plugs. Absolutely dead. The starter motor churns over but as there's no voltage to the plugs, it's just a dead duck.

Is it condensation and shorting in the kill switch?  I'm not a mechanic, so does anyone have any ideas??

Thanks guys...

[750goes]

check your wiring connections from the points to the coils - and the earth at the coils for good contact. then if no go - look for power to the coils from the kill switch... then if still no luck - open the headlight bucket and enjoy finding your hot wire to the kill switch..

will it kick start

[Hush]

Sounds like a kill switch problem all right

[ev0lution7]

wire in the headlight bucket is black going into the switch and comes out black w/ white and goes into the harness same color and has a "double" plug at the coils... check that with the kill switch "on" for 12+

[HondaMan]

If you have spark at the points, then the coils are getting the current OK.

If the resistors in the spark plug caps are getting old and burned out, it can be hard to start in this situation: especially so if the plugs were wetted during that 30-second run you did before storing it. The plugs might need a bit of heat to remove the now-conductive fuel residue.

So, try this: check to make sure the plug caps are screwed tightly onto the plug wires. Remove the plugs and make sure they are not black and sooty (replace or sandblast if so).

Finally: if the condensors are more than 5 years old, replace them. They can make for a difficult startup after storage. When they are not used much, they shrink inside and their capacitance drops off, making for lots of sparking at the points and resulting loss of coil spark voltage, especially at starting speeds.