Dom,
I'm sure the most common cause for this is a change in ignition timing. I assume the mechanic left the Lightspeed system alone, but did the normal routine of resetting the timing of the mag. If the two timings are exactly the same you will likely get the same drop on each, or maybe a little less drop on the Lightspeed. I've observed that most annuals include resetting the timing, but rarely will the mechanic state what it was before the change, which would be very useful information. I'll bet he advanced the timing of the mag by maybe 2 degrees. Just a guess :-)
Gary
Um – er - (headscratch) – fellow LMLer’s – since the annual performed by maintenance outfit (not necessarily significant) I notice I get a drop around 80 RPM on the Lightspeed ignition during run-up, whereas before it was barely noticeable.
Been wondering why. Changed my iridium plugs two days
ago just as a starting point but no difference.
So thought I would ask the experts herein.
Thanks
Dom Crain