I've had a somewhat similar experience with my GRT 4000 with a G3i electronic ignition. When I first installed the ignition, I got apparently correct tach readings up to about 2200 or so, then wildly ...
Thanks - I appreciate the replies to my question.
Just after posting the question, I inadvertently unsubscribed from the list so just read a couple of the replies today, thus the delay in acknowle ...