James, Welcome!!!!!
The Voyager 1200 or XII is very easy to work on. Like yourself I've never torn an engine apart but I've done lots of wrenching (shade tree mechanics) and working on the Voyager is a breeze, seriously. Not only did Kawasaki build a bullet proof engine but there are a lot of skilled and knowledgeable folks on this forum. As for the mileage, if the bike runs don't sweat it as there are many XII's with over 100K, several with 200K and even a few with over 300,00 miles on them. When changing the oil don't look at the sight glass, use Shell Rotella 15w40 with filter and put 3qts 22oz (no more and no less). \
These bikes have a certain/special whine to them similar to George Jetson's space car, this is due to the square cut gears (as I've read, never checked myself but trust others).
Give the bike a good once over, change fluids (brakes, clutch, oil), check tires for proper air, check the rear end fluids and read read read!!!!
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There is tons of information on here and the search engine works great. If you have a question and can't find the answer just ask!!!
Rest assured others have wondered the same things you might think of.
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Again WELCOME to the AVA