
Originally Posted by
OddDuck
I've been having CDI trouble with the 900ss lately so maybe this is useful... Difficulty starting and running, especially in cold / humid conditions. It got to the point where it very nearly wouldn't start at all. Ran OK after it had been out for a good spin though.
I tried cleaning the spade connectors and making sure they were tight (12V doesn't take much to interrupt; dirt, oxide and oil can do that), some improvement but nothing major. I did the same to the main relay and found the push in connectors were oxidised quite badly, some CRC2.26 and several insertion / removal cycles (to clean the connectors) did wonders for the bike.
Problem resumed earlier this month, following parking up in the shade at work.
I took the CDIs off, wiped the dirt off and had a look at the potting. Most potting is epoxy resin or silicone rubber (flexible). In my bike they used silicone rubber. It's good for the electronics because it cushions as well as seals. Close examination showed what looked like hairline cracks on the surface of the potting. Not too surprising on a 1995 bike.
Now for the good bit... I fired up the fan bake oven and cooked them for 6 hours at about 65 - 70 C.
The reason for doing that was water ingression. CDI's have high internal voltages and if water is getting in then that voltage will start dissipating via insulation leakage. We use this technique at work a lot to dry out electronics that test low for insulation values; it's surprising how quickly it comes back up. You don't have to take it to boiling, just hot enough for long enough in a dry environment to get the water out.
After cooling and reinstallation of CDI's, the bike fired up immediately and ran better than it's run in years.
I want to stress that this is diagnostic or last resort stuff. Do it only when you've got cash and a source for spares lined up. The fix is temporary at best - I've tried coating the outside of the potting in silicone grease, but the bike's showing signs of having trouble again (it's only been three weeks). Replacing the potting would be ideal but that's a saga in itself, and anyway there'll be electrolytic capacitors in there which should be replaced as well. New CDI's for me when I can afford them.
Apologies for the novel, good luck and let us know how it goes. Now for the jokes to begin...
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