SOHC.co.uk Forums > CB500/550
Cb 550 ss spain
deltarider:
I've scanned all the posts here and - frankly - I can't believe the ignition was not mentioned before. Not until your last post, I mean. Ignition is where I'd start. Sparkplug noses can give a clue ofcourse, but here are some simple tests, if you happen to run the standard ignition.
Faulty condensers may cause arcing as shown in the vid: https://www.youtube.com/watch?v=t3cuvGVwnjI At the breakerpoints a bit of sparking is normal, excessive sparking or arcing is not good and can indicate a bad condenser. In this vid the left condensor (1+4) is bad, right condensor (2+3) is good.
Video: courtesy Ulf Penner
When you're at it, check none of the forked connectors at the breakerpoints accidentely ground to the plate. This grounding can be intermittent! Especially the 2+3 connectors are at risk, as they have a crosshead nearby.
To check the quality of the sparks, I have this simple tool: a copper wire which has an alligator clip on one end and is stranded open on the other.
Two ca. 0,4mm thick pieces cut out of an old credit card to be used as isolators.
Here is how it works.
Isolate breakerpoints as shown in the pic.
Attach alligator clip to the small center bolt of the breakerpoints, either 1+4 or 2+3.
Unplug plugcaps 1+4 or 2+3. You could unscrew the sparkplugs, but test can also be performed with reserve plugs.
Connect plugcaps to the sparkplugs that are out and are firmly (!) grounding to the engine block.
Turn on the ignition. Relax, both breakerpoints are isolated, so the coils are not taxed.
Simply move the stranded copper wire loosely over any part of the engine or frame (unpainted).
The effect will be a rapid serie of sparks very similar to when engine is running.
Verify the sparks are white or blue and not red.
Compare to the other set.
The advantage of the method is, you hardly use power and it will save you cranking the engine.
But above all: due to the stranded copper wire, there is this very rapid firing, which results in much more realistic sparks than by just holding a sparkplug to the block and crank one turn. The difference is huge.
How sure are you about the plugcaps? The coils secundary is around 14-15kΩ, so in total a circuit (either 1+4 or 2+3) will read 24-30kΩ if you have resistor plugcaps. If you read more than say 31kΩ, unscrew plugcaps from the leads to be checked individually. Ideally resistor plugcaps will read around 5-7kΩ. When over 8kΩ, replace. BTW, do not run resistor caps and resistor plugs. When you have the choice, I'd prefer resistor caps. Realise that like sparkplugs, plugcaps have a limited lifespan, so when in doubt, replace.
Have you verified the advancer advances and retards smoothly?
I hope you're not offended, if I have posted what is all too familiar for you. Just ignore.
murdock:
I would not be offended at all, what remains here will serve others
I usually check the ignition with the lights off, when a capacitor is defective, sparks are sometimes smaller than in the video
the plug caps are resistive 5 ohms and the ngk d7es plugs are no longer available, only the dr7es that are also resistive, that does not add up to 10 ohms, the sum of the 2 resistances is half of one, I will order a new set of spark plugs, I think I have a saved capacitor, I will review mine better, and I will try the method of isolated points, thank you very much
philward:
Murdoch, I think D7EA are the correct plugs to work with resistor caps - they are available
murdock:
d7ea will it be the replacement ??? I can't get the d7es around here, someone is using them and could I confirm it?
philward:
http://www.sohc.co.uk/index.php/topic,25753.msg235941.html#msg235941
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