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Discussion Starter · #1 ·
2014 model 750. Our first year with Claas, came form a JD 9670


We've plugged 2 corn bin sumps and a bean bin. Not many happy campers around here. Luckily only one small bin of bins, the bean bin plugged the center sump. On the corn, we're plugging the side sumps which have a bar across them that trash is getting caught up on.

At first we were definitely running the top chaffer too far open.

Now in corn, we're running 11 on top chaffer and fan at 1200. Bottom sieve is open to 8. We're not returning any clean grain. Still getting sticks in sample and broken cob tips. Any suggestions?

We're running the standard frogmouth sieves.
 

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We struggled with the same issues with our 760 . I even bought a set of rounbar aps grates thinking that would help but no noticeable difference. Most of our corn was hailed on and the ear size varies greatly so I thought that was most of the trouble.
 

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2014 model 750. Our first year with Claas, came form a JD 9670


We've plugged 2 corn bin sumps and a bean bin. Not many happy campers around here. Luckily only one small bin of bins, the bean bin plugged the center sump. On the corn, we're plugging the side sumps which have a bar across them that trash is getting caught up on.

At first we were definitely running the top chaffer too far open.

Now in corn, we're running 11 on top chaffer and fan at 1200. Bottom sieve is open to 8. We're not returning any clean grain. Still getting sticks in sample and broken cob tips. Any suggestions?

We're running the standard frogmouth sieves.
This really confuses me because I had a terrible time this year getting our corn through the bottom sieve at 20 and I've never ran it more closed than 15.

Are you choking out the air through the top sieve by having the bottom too closed? I close the top sieve till losses start to appear and then open it up 1mm. Cylinder at 350-380 rotors 400-420 concave 22-25.
 

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Discussion Starter · #4 ·
We had bottom wide open, didn't make any difference. I guess I will open it again tomorrow and confirm it again. I know I was surprised when I started closing it down, I had it down to 5 to get substantial corn returning. Funny thing is the difference in grain returned from 7 to 8 is pretty significant. At 8 no clean grain is returned, expect when going through the occasional draw, in which case its only returning for a few seconds.
 

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I'm pretty sure the 2014 model combines have the same long finger sieve in the bottom like on top. If so, at a minimum you need to set it the same as the top sieve. Once I got the part number for them I put them in my 750TT. They really let me run tight, clean the sample without overloading returns with grain. Run them on 1-2 in beans, nothing but trash in returns. 8-9 is the tightest I can go in corn before loading returns up with clean corn. That is about 40% tighter than with previous sieve.
 

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I have 750 as well and corn is 21 percent and have found running top at 12, bottom at 9 or 10 and fan cranked up to 1450 got rid of all sticks and very minimum cob pieces. I am also running the round bar from HHS which is supposed to help a lot with cob pieces not sure about stalks. I would say crank up the air because I personally find it very hard to lose grain out the back of a Lexion.
 

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I had a lot of sticks this year too, I run my shoe at a 35 to 45 degree angle, wide open is not good, close your chaffer a little at a time. I never adjust my shoe during the season only the chaffer and wind speed. I have done this for decades on my red combines good luck..........
 

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The fingers at the front of the chaffer (upper sieve) just overlap the front of the sieve. They do not cover any area wider than the rest of the sieve, or any area going directly to the clean grain cross auger without passing through both upper and lower sieves.

The sticks are always going to be around, especially in dry stalks, no matter what combine. They come from the top part of the stalk and are a result of threshing action and really do not increase or decrease with threshing speed. The key to getting rid of them is to not let them pass through the upper sieve. The jetstream cleaning system in the lexion allows you to run a tighter upper sieve at lower fan speeds without reduction in capacity. The new deep-tooth lower sieve further helps this out by letting ample air pass through even when tight.
 

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Remember you can open your sieves to far and the fingers then become problematic.
Get out and look at them with your eyes.... The pitch might be to great...

All the technology in the world and grandpa still does it best.
 

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Have you tried reducing cylinder speed and / or opening your concave some so you are not making little sticks? I have had success with this in the past. It surprises me sometime how slow and open the concave can be and still remove the corn from the cob.
 

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Cylinder is at 280 rpm and 33mm
33 seems awfully wide to me... If you aren't seeing rotor loss at that I wouldn't worry, but I have never run mine over 28-29.

What type of grain flow are you running? I have been running mine pretty wide open lately and other than some bits of cob it looks really good... In this variety lol.

My settings tonight where both sieves at 24, cylinder 280, concave 27, rotors 420, fan 1400. Was running 4,500 bph give or take in 21% corn.

But I have also had some trouble with stalks bits in certain varieties this year... I just don't have the balls to close my sieves that much lol!
 

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Discussion Starter · #16 ·
33 is getting the job done. I check nearly every time when I wait for the grain cart. We're running 3500-4500 bph without losses. Ground speed is 5-6 mph depending on field conditions, all our fields are rough from lots of rain this year. Wish we had tracks.
 
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