Ignition issues spark plug

[CaxiasR45]

Hi everyone

After my presentation, my first "cry for help" topic.

I have on my 78 / R45 the 860cc Siebenrock kit and an electronic ignition. Riding 500 km everything was OK. After a week resting in the garage, the bike don't want to start, i take the spark plugs out to see if there was any spark and i found this:

Press start button, I get spark on the left, everything OK, press again now for the right side and I see a spark, but after 1 or 2 seconds, without pressing the start button I see a spark again. I change spark plug, try again, and the problem continue there.
Anyone with any idea for what's causing that second spark ? Ignition Relais ? Coils ? It only happens in one side...

Thanks in adavnce

[gspd]

Welcome to the forum CaxiasR45.

Both plugs should spark at the same time, once per crankshaft revolution.

It's normal to occasionally get ONE random spark when turning the ignition on or off.

Does the bike run well? Is the timing correct (on both cylinders) when checking with a timing light?

[Rob Frankham]

It all depends on what sort of electronic ignition you have...

The OEM contactless ignition system fitted as stock to later models has a feature that switches the igntion module off if it doesn't receive a signal from the sensor for a couple of seconds. This would cause a spurious spark but it should do so to both plugs at the same time.

If anything, I would say that the lack of this second spark at the left plug may indicate a problem with that side rather than the right.

That being said, if you have a spark at both sides and the bike has been running OK before, I would tend to think in terms of a fuel problem rather than an electrical fault.

Rob

[kmisterk]

Welcome to the forum CaxiasR45.

Both plugs should spark at the same time, once per crankshaft revolution.

It's normal to occasionally get ONE random spark when turning the ignition on or off.

Does the bike run well? Is the timing correct (on both cylinders) when checking with a timing light?

is this true for most/all R-series? IE, say, an R100T?

[gspd]

Welcome to the forum CaxiasR45.

Both plugs should spark at the same time, once per crankshaft revolution.

It's normal to occasionally get ONE random spark when turning the ignition on or off.

Does the bike run well? Is the timing correct (on both cylinders) when checking with a timing light?

is this true for most/all R-series? IE, say, an R100T?

Yes, except the random spark thing. Doesn't happen with points ignition, only electronic.

[kmisterk]

Welcome to the forum CaxiasR45.

Both plugs should spark at the same time, once per crankshaft revolution.

It's normal to occasionally get ONE random spark when turning the ignition on or off.

Does the bike run well? Is the timing correct (on both cylinders) when checking with a timing light?

is this true for most/all R-series? IE, say, an R100T?

Yes, except the random spark thing. Doesn't happen with points ignition, only electronic.

At what stage in the opposing cylinder does the spark happen on the non-combustion side?

[gspd]

At what stage in the opposing cylinder does the spark happen on the non-combustion side?

It's called the 'on the overlap'. Both (intake and exhaust) valves are partially open so the spark is simply wasted.

Both sides fire at the same piston position: xxx degrees before top dead center (BTDC).
The actual 'degrees' depends on RPM and can vary from model to model (and from tuner to tuner).
If in doubt, use the factory timing marks on the flywheel.

[kmisterk]

It's called the 'on the overlap'. Both (intake and exhaust) valves are partially open so the spark is simply wasted.

Both sides fire at the same piston position: xxx degrees before top dead center (BTDC).
The actual 'degrees' depends on RPM and can vary from model to model (and from tuner to tuner).
If in doubt, use the factory timing marks on the flywheel.

Interesting. Thanks for the info