Missing in rain
One possible solution will be using black hi/temp silicone on plug caps. Put a light coating where rubber meets plastic on top and bottom of plug cap, then put a heavier coating where plug wire meets plug cap. See if that does not help. Good Luck and Ride Safe.
Rule #1 Watch out for Number 1.
Rule #2 Remember your Number.
There is nothing wrong with a little shooting, as long as the right people get shot.