Topic: 1976 cb550k2 - NO SPARK - 10v at igniton coil primary = Is that enough?

[mpaar]

All,

I am new to the forum.  Can you help me diagnose my NO SPARK?

1976 cb550k2 - NO SPARK - 10v at ignition coil primary (Bk/W wire to both coils) = Is that enough?

No spark at points.  Good battery. 

mike

[HondaMan]

That's enough to make a spark, it will be a weakish one, though. The normal running voltage at that wire is closer to 12.0 volts. Maybe try adding a small battery charger to it while troubleshooting, as these small batteries don't hold much charge.

Make sure the points are opening and closing: you can either kick over the engine or (on the 550 this is OK) turn the engine slowly with the big nut by the points, but take the sparkplugs out of the engine first. Let them hang and lay against the engine to check for spark (don't try this on a 750). The spark happens when the points open. If the voltage is low, it might help to have a semi-darkened garage to see the spark. It is bright at 12.6 volts, but dim and short below 11.0 volts.

Find the main battery ground cable and the Green wire's grounding terminal on the frame. It may be under the seat, or under the gas tank. Disconnect them and clean the wire's connector and the shiny spot on the bike where these bolt down: this is the main grounding system. They get corroded when not used for a long time. Add a drop of oil to each one when putting them back on. The oil will squeeze out of the contact surfaces and then reside as an airtight seal around it for a long time.

[newday777]

All,

I am new to the forum.  Can you help me diagnose my NO SPARK?

1976 cb550k2 - NO SPARK - 10v at ignition coil primary (Bk/W wire to both coils) = Is that enough?

No spark at points.  Good battery. 

mike

Welcome aboard the forum Mike

10 volts at coils is low.
"Good battery "
What voltage do you have at the battery? It should be 12.1-12.7 volts.
Do you have clean ground at the coils and at the battery ground strap to the frame(bare frame exposed and cleaned/light dialectic grease?
Do you have TEC points and condensers(from Honda) or aftermarket points and condensers? Cheap Chinese are problems.
Did you check voltage at the points?

[Deltarider]

[...]
1976 cb550k2 - NO SPARK - 10v at ignition coil primary (Bk/W wire to both coils) = Is that enough?
No spark at points.  Good battery. 

Hard to tell. It depends. With the engine running over 3000RPM, you should see more ofcourse.
What do you exactly mean by No spark at points? With IGN ON you should have 10V or more at the points when open. Or, if you prefer to measure at the coils primary, temporarily isolate the breakerpoints like in the pic below* and repeat the measurement. In principle you should then see no more voltage drop than 0,5V at the coils primary, but personally I wouldn't worry if it is 0,7.
Or do you mean: no spark at the plugs electrodes? In other words: what's the issue?
* After removal of the plastic isolators, clean points surfaces just to be sure. Points like to be clean.

[Deltarider]

Another thing. You may have read in this forum about a 'charging deficiency'. Here is the good news: IT DOES NOT EXIST. All owners of models which have that idiotic lights-always-on arrangement (US only) are strongly advised to temporarily remove the according fuses before working at their bikes.
All modifications Honda was forced to by US regulators on already existing models, were stupid.

[HondaMan]

All modifications Honda was forced to by US regulators on already existing models, were stupid.

No argument there!