I've run a 7720 II since 2000. Some things I've done for corn and soybeans. Added a fixed air foil chaffer and really increased the machine's capacity. New rasp bars and a hi capacity concave helped too. I have grain extensions for 200bu capacity and use duals for muck ground. As with any machine, keep the engine compartment clean of grain dust.
An important lesson I learned last year is how to properly grease the intermediate cylinder drive belt (lower sheive). Slow cyl down all the way, take breather plug out of lower sheive, grease zerk in back of shieve until grease comes out of breather hole (do not use the zerk in front), install breather plug, run cyl. speed up and down a couple of times and refill grease in the same previously described manner.
7720 II are good machines. With the airfoil chaffer, I run 4+mph in 180bu corn and 643 head, and I use a 920 head in beans and wheat. Good luck with the machine, you'll like the capacity over your previous setup.
An important lesson I learned last year is how to properly grease the intermediate cylinder drive belt (lower sheive). Slow cyl down all the way, take breather plug out of lower sheive, grease zerk in back of shieve until grease comes out of breather hole (do not use the zerk in front), install breather plug, run cyl. speed up and down a couple of times and refill grease in the same previously described manner.
7720 II are good machines. With the airfoil chaffer, I run 4+mph in 180bu corn and 643 head, and I use a 920 head in beans and wheat. Good luck with the machine, you'll like the capacity over your previous setup.
