Combines Straw in the bin of my F

I would make 3 guesses on this. First how dry is grainIJ If overly dry it will be nearly impossible to keep straw out. Redcoat was bad about straw in tank if grain under 12%. Next, cylinder clearances maybe to tight, third cylinder speed maybe to high. I would start with slowing down cylinder speed, then open up if moisture was in 13%+ range. We find 15-17% is our cleanest point with an F. Drying charges maybe make it more cost effective to have some dirt in tank as opposed to paying shrink.

Dumb question, but never over-look the obvious -- are you using the small grain chaffer or a corn chafferIJ We were told that the corn chaffer would work in oats and tried it once on our FKS. It put a lot of staw in the bin. We went back to the drudgery of changing the chaffer each year. Now it is much less of a chore on our M2...

just a little side comment.after years of fighting changing top chaffers on e-to g combines we discovered it is alot easier to get the old out and other in if the shoe is all the way to the rear of it's stroke. thank the gleaner engineer who figured out the chaffer track on all new combines since 1972.(first l's) we always thought it was worth the time running a grain chaffer and a lot easier to adjust

I didn't mention that I have all my screens in place. However I do have a air foil chaffer. I was getting straw in the bin befour I changed to the air foil chaffer. Thank You. John