where can I find tech information for a 1985 yamaha tri moto?

Answer 1

For future reference, always give year, make, "engine size", and "model #" when asking questions. We need all of that info to give an informed answer.
http://www.3wheelerworld.com/1985yamahaspecpage.shtml
If this isn't what you're looking for, purchase a shop manual before they go out of print.
http://www.motocom.com/motorcycles/

Answer 2

http://www.clymer.com

find the info at clymer.com. They offer a wide variety of shop manuals that offer all kids of info....