No Spark

[yorkie_chris]

For some reason I can't seem to get a decent spark from my coils, even with direct connections from battery to coil (battery shows 12.6v)
Using a multimeter on the coils shows pri and sec resistances to be well within spec, the plug cap is ok and have tried both plugs, thinking whats the chances of both plugs failing at once, especially as they both show continuity.

Direct connection gives tiny sparks at the plugs, like hair thickness, but nowhere near a decent spark, and turning it over with the starter gives nothing at all.

Earth to the coils is solid, showing no resistance, and I have been using a jump lead to get a decent earth when testing the plugs.

Multimeter to all the connections to the ICU multiplug show resistances within spec, power where it should be, 2 wires which have earth continuity.

Whats going on? I'm out of ideas, and my bike is off the road

Help!

Chris

[TSM]

what about the earth that links to the back of the engine to the battery?

[Spanner Man]

Good evening Yorkie.
Have you tried bypassing all the safety switches? Such as the clutch switch & the sidestand one.
If you have an alarm fitted this sort of malarky can occur, I'm afraid the only way to test an alarm is usually to remove it. Some Datatool alarms however can be bypassed quite easily.
Sometimes with ignition components correct readings are obtained when testing with a multi meter, however the component can break down under load, so the only surefire way to test ignition components is by substitution with a known good one.
Bloody pain innit!

Cheers.

[yorkie_chris]

OK this is part of a rewire, no safeties in place.

Have checked for voltage at the ICU, and as the immobiliser and the safety switches kill the main ignition hot, this means that they're not f#cking the job up.

Basically have tried with direct connections and neither coil is giving a decent spark, whats the chances of a lowside knackering both coils?

However, will check the earth strap, and am just in the process of ordering a spare ignition coil to try...

[yorkie_chris]

Ok, earthing everything back to the battery directly gives same result.

Power direct from the battery gives same result.


How big a spark would you expect to see? whats healthy look like on these if anyone can describe it as I'm used to car ignitions and points and condensor setups.

Chris

[yorkie_chris]

HAH Success! (ish)

Took the plug cap off and stuck a pin in the end of the lead, which gave me a right f###ing belt when I accidentally brushed the croc clip on the -ve terminal.

Juicy 1/4inch sparks will jump off the pin to earth.

It appears the plug caps are goosed. (even though they still show the right resistance ??)


However, still nothing when turning it over with the black box connected.

[rictus01]

I'll prosume you have cleaned the plugs and they are in good condition and gapped corectly.

right well you've sort of found the problem by accident it would seem, if you screw the spark plug directly into the core of the HT lead and ground the plug body to a bolt on the bike you'll find it works as it should, this will show the problem to be in the plug cap itself.

If you look inside the plug cap, you'll see the brass contact and across it a slot, with a screwdriver undo this, once undone a spring and fuse type thing will come out, this fuse (ceramic) will be your problem, in the short term you can bridge this with something, but as it smooths out the spark*, I wouldn't go far it's more a get you home thing.

get your self new plug caps (a few £ each from most motorbike shops), If you get the champion straight ones the boot on them is slightly larger and gives a good seal so it stops the front plug issue as well


*this isn't quite correct but will do for now.

Cheers Mark.

[yorkie_chris]

The spark plugs show spark when connected that way.

Any idea why both would fail at once? maybe the shock of being dropped? (the engine stopped as soon as the bike hit the floor)

Still nothing when cranking the bike though, all the sparks I've got are from (dis)connecting the coil -ve and earth with a little test lead.


Chris

[rictus01]

Originally Posted by yorkie_chris

The spark plugs show spark when connected that way.

Any idea why both would fail at once? maybe the shock of being dropped? (the engine stopped as soon as the bike hit the floor)

Still nothing when cranking the bike though, all the sparks I've got are from (dis)connecting the coil -ve and earth with a little test lead.


Chris

if both went at the same time then it'll be a common earth, I'm guessing you're providing a direct earth to the coil when testing ?.

try a jump lead from the negative to an engine mount if this sorts it out then the main earth lead is dodge* and you'll have to either replace or re-terminal the end (s).

*the hard terminating eyes can fracture and although still connected will fail under load.

Cheers Mark.

[yorkie_chris]

Originally Posted by rictus01

I'm guessing you're providing a direct earth to the coil when testing ?.

I was doing using a jump lead, but with a pin in the end of the HT lead then the spark will go anywhere it should, engine bolts, coil mounting, subframe etc. without the jumplead connected.