1980 Gs550e - new coils fitted - no spark

[StevieB]

Hi haven't been on here for a long time - my Gs has been in storage for 18 months due to relocation. It was running before storage with carb rebuild to resolve fuel issues.

Took out of storage with drained carbs, fresh fuel, new battery and replaced the coils as thought cause of occasional missing. Replaced with Hendler coils. 

Now have no spark - tested with all plugs removed, and to test each plug earthed spark plug in ht lead to good earth on cylinder head and cranked over - no tank fitted. Original plugs, new at carb overhaul. Thought unlikely all four fail.

Substituted one of original coils (continuity of lt and ht good). Still no spark.

Just after advice on electrical testing to find the fault. I'm not an electrical expert but have a basic understanding. Was thinking is it possible to test the lt inputs to each coil (multimeter to each input and to earth?) - not sure if the lt circuit through coils are one continuous loop or separate circuits. The online Hendler coil instructions state the lt wires can be connected either way?

Would like to test system logically from someone with better electrical knowledge and experience. Thanks

Edited April 22 by StevieB
Spelling auto correct mistake

[gs7_11]

Check that you've got 12Vdc with respect to ground (engine) at the orange/white (?) Wires to the coils. These can go either way round.

The black & white (?) Wires are earth side triggers to the points or electronic ignition back plate.

[StevieB]

Thanks for the advice, will check if there's a 12 V supply to the coils to the mentioned wire connection. Hoping this will be the case rather than cdi/signal generator issues. Will post back what I find.

The one thing I don't understand is - if there is continuity when you resistance test the LT wires on the coil,  how can it have a 12 V and electrical signal feeding at each end of the coil LT? I'm not an electrical expert!, just doesn't make sense to me.

Thanks

[Gixer1460]

The 'signal' wires ground out the coils to collapse the primary magnetic field and induce a mega voltage in the secondary whose only path to ground is through the spark plug.

[gs7_11]

13 hours ago, StevieB said:

 

The one thing I don't understand is - if there is continuity when you resistance test....

What Gixer1460 said, plus "continuity" in this case is a small resistance, usually 3-5 ohms, which is enough not to be a dead short. With 12V it will draw 4 Amps and it's pulsed, so not on all the time.

[StevieB]

Thanks, makes it clearer to understand.

Just tested coil inputs at plug connector with ignition on, not cranked engine. 12V on both coils orange/white.

No  volts on Left coil signal connection, 0.5 volts on Right coil signal connection.

I will disconnect signal generator and cdi igniter and continuity test wires between each component to test the loom and connectors. Will also clean each wiring connector. Don't want to test anything on signal generator or cdi as I don't know how to test them and don't want to destroy any components.

Thanks

[StevieB]

Hi - been doing a lot of research for my GS no spark issues. A lot of info on past forums here and GS resources. Also got a Clymer manual in addition to the Haynes one.

There's a procedure for resistance testing the unplugged signal generator. Each side of the signal circuit should be 60 - 80 ohms. Mine both read 68 ohms.

So gave all contacts another clean, retested coil inputs - still the same - primary 12V, secondary signal wire 0V left, 0.5V right.

Reassembled all connections, connected 3 and 4 plug leads to plugs and earthed removed 1 and 2 plugs in caps to head.

Result - spark.

Did the same on other side - spark again. I'm pretty sure if all plugs removed and earthed to head for a start, you don't get a spark.

So not exactly sure why there is a spark now, maybe just resolved from cleaning plug connections.

Primed the fuel to the carbs and took a while but started fine. Quick test ride and all good. So happy to take it out for ride.

Just got a leaking fork seal to replace - but that's easy - not like electrics!

Still not sure about the 0.5V on the right hand secondary coil wire? May have always been like it but it runs fine. I had no knowledge of testing ignitor cdi.

Thanks for the previous advice.

[andyroach]

A lot of electrical problems are down to dirty/corroded connections. first port of call with electrical problems is always clean all connections and check you have voltage from the ignition.

Glad to hear you got it sorted though. Enjoy the 550. I had one and it was a real laugh.

[StevieB]

Thanks Andy, yes real nice to ride something old. Brakes take a bit of adjusting to compared to modern bikes, but handles surprisingly well for a 40 year old bike