Re: Tachometer problems...
"I'd assume the tach's probably just shot, but I'm pondering other possibilities also."
You know, strangely enough I have not heard of a Tach being shot.. I've heard of problems in other areas making the tach appear to be wacko though.
One that come to mind is a sticky kickstand switch (Though usually hand-in-hand with this is that bike just stalls when you put it in gear.
I'd check out the coils and see if the problem could be there. Chances are with an 85 you are still looking at the originals..
I'd go with jm1515 on the checking out coils and igniter
Patriot Guard Rider
2000 VN750 Sere (Serendipity)
1990 GL1500 (Ole Blue)
1986 VN750 EVie (project bike, heavy custom)
VROC # 11628 / 25000-H
ARVROC # 12 Coordinator and Crowd Control
OKVROC # 18 (H)
TNVROC # 45 (H)