Quote:
Originally Posted by Bob Ashlock
The tach jump is a clue. This could mean the 12V power to the CDI is dropping out since the CDI has an internal 33 or 120 Ohm pull-up resistor to inyernal 12V that feeds current to the points. The tach is connected to that signal. OR, have you checked to be sure the points are gapped properly? (Around .016 inch). Sometimes their rubbing block wears down so much they are only opening a few thousands of an inch and completely close as they heat up.
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Hey Bob,
Really appreciate you chiming in – that’s super helpful!
I had no idea about the CDI’s internal pull-up resistor and how that could tie into the tach signal. Makes a lot of sense now that you mention it. I’ll check the 12V feed to the CDI and see if it’s dropping out when the problem happens.
I’ll also take a look at the points gap. Haven’t measured it in a while, so it could very well be worn down more than I thought. I’ll set it to about 0.016” like you said and see if that helps.
Thanks again for taking the time to explain – much appreciated!
By the way, if the CDI is losing 12V intermittently, would you expect the engine to just cut out instantly, or could it also cause the “runs fine for 30 minutes, then dies” type of symptom I’m seeing?