Hoosier here. Welcome Butch. Sounds like you walked into some great deals.
Change oil frequently. Every ride or two. 10w40 is what Kawasaki recommends. I use valvoline, but the site expert, Stewart, would say Royal Purple is what you want. Its a little more, but well worth it, I'm sure.
NGK plugs, B8ES they can be bought from Oreilly's for 2 dollars a plug. Keep an eye on their color, until you get the bikes dialed in. Dark Brown is a good tuned motor. Black is rich / white or green is lean.
Use premium gas with the highest octane and quality you trust and stick with that fuel. I like Amoco Gold. I also use Camm II to race (110octane). Its found at some Speedway Gas Stations. Use a high quality name brand synthetic two stroke oil at a ratio of 44:1. I use Klotz Super Techniplate or R50. Smells good and works good. Lots of personal preferences come into play here, but the important thing is to be consistent. Its hard to tune if you have too many variables.
Attica, the Badlands, is out west on I-74 almost to Illinois.750 acres of Sand Dunes and Wooded Trails. $20/day
Dugger OHV Park is 1200 acres of dense wooded trails. registration with the State required. $10/day
Haspin Acres, Laurel Indiana, Lots of jeep trails and sippy holes, super Dusty, with 2 Motox Tracks $15/day
Lake Waveland has a Loop Trail, but I have not been there.
Also, there is supposed to be another OHV place called Silverlake, but I do not know if that one is open yet.