HELP..Where did my sparks go...?

[Anonymous]

Help! Just picked up a 1978 GS550E from a guy I used to work with. Been standing for a couple of years but only 14k miles and tidy condition.
Put a new battery on it, fresh fuel and it started. GREAT. Unfortunatley the idle was all over the place, racing and dropping without me touching the bike. Upon investigation (squirting wd40 on the manifolds in turn) the rubber inlet manifolds were leaking air badly ( and no3 carb was overflowing too). Next step, removed carbs, removed float bowls. Blasted carb cleaner through the jets, reset float heights with a vernier, cleaned up inaccesable bits of engine and chassis (removed yellowing laquer from the engine, routed breathers and overflows properly and clipped a few dangling wires back into the chassis wiring loops). I used silicon RTV sealant to seal the manifolds to stop the air leaks. Put it all back together, filled with fuel, primed carbs. Won't start!!! Removed #1 plug and signs of fuel. Tested it against the cylinder head and no spark. All other plugs the same, signs of fuel but no sparks.

Where do I start looking first for my missing sparks? All my electrics/ lights etc. work and the starter turns over happily. Main fuse is intact also.
I've tried replacement plugs and have a second set of coils but the originals were working ok. ANY IDEAS???? What could I have distrubed that has killed my ignition?

[Anonymous]

you said you tidied up wiring check every thing you touched more than likely you have unpluged something or plugged a wire in wrong .they do not break down while you are fixing them normally ozman

[argonsagas]

you said you tidied up wiring check every thing you touched more than likely you have unpluged something or plugged a wire in wrong .they do not break down while you are fixing them normally ozman

Agreed. Seems very likely you have opened a connection somewhere without knowing it, but you may also have a poor connection with your ignition fuse. Make sure it is clean.

I believe you have a standard ignition, using points/condensors, so check that you are getting input voltage at the coils when the engine turns over.


If not, using a meter, check that you have power to the points It is difficult to check the condensors, and it is highly doubtful two would fail at the same time, but look for a spark as the points open.

[Anonymous]

Thanks for the replies guys. I have been out this morning and double checked all the connections i have touched and they all seem properly connected. The only one I recall having disconnected was the black and the white leads from the points/condensors to the coils. This lead runs under the engine block and round the back of and over the top of the carbs. It was hanging down onto the carbs so I have clipped it up back out of the way. I have checked it and both wires are securely connected.

Bit of a beginners question now but where do I attach my multimeter probes to test the points and coils? I'm looking for 12 volts at the low tension input to the coils yes? One probe attaches here, the other end?
And what about the points?, apart for looking for sparks across them (duff condensor) where should i be checking? should i check anything else?
The main fuse seems fine. Its a mystery this one...........