GT550 No Spark at plug

[CalJoe]

Working on a 1975 GT550 that has been in storage for 15+ years. I'm not getting a spark on any of the plugs and I've run out of ideas.

New battery
Coils tested on running bike - no issue
Constant power for all 3 coils
Power back from points

Any suggestions on where to look next? Could the condensers be shot but still send enough voltage back up to light a test lamp? Seems strange that all 3 coils are not producing a spark... Any suggestions would be greatly appreciated.

[jabcb]

What did you mean by:
Constant power for all 3 coils?
Power back from points?

[CalJoe]

Thanks for the reply

Constant power for the coils is present (from ignition) and power is returning to the coils from the points (when the points are engaged/disengaged appropriately). Hopefully the diagram below explains the situation better. This is the first opportunity I've had to work with a system such as this...

http://s1280.photobucket.com/user/jwcla ... 4.jpg.html" onclick="window.open(this.href);return false;

[Alan H]

What gap are the NEW plugs - 25 thou/0.6mm?
Cut 1/4" off HT leads and screw the caps back on.
Are they resistive caps?
Measure cap resistances to see if they're OK. If not get some non-resistive caps.
Put all three plugs in the caps and put the plugs on the cowl so you can see them spark.
Flick the points. Check to see a spark. Weak = possible dud condenser.
Fit the correct type of condenser for the coils you have - Denso and Kokusan are different.
DON'T use resistive plugs. ('R' in the type printed on the plug.)
Does the correct plug spark? Left points wire is white or black/white. Centre is Black/yellow. Right is Black. On early models (and some later ones) the wires connect separately, not in a block connector, make sure they are correct.


That should give you an interesting afternoons' head scratching anyway!!!

[Suzukidave]

Is the ground strap from the engine to the frame nice and clean attached ?