Combines 1688

How many rpms does the rotor fall when the engine falls 200IJ If you push it harder, what happens, does the engine stall, or is it the rotor that stallsIJ This sounds allmost simular to the problem I have with my 1680 since I had the pump rebuilt. I just had get used to pulling the engine down further than I was used to. Once I pulled it down to 2500 from 2740, it would hold there. If your rotor keeps falling rpms, look into the spring on the driven side of the rotor belt. If its weak and colapsed, it will let the belt slip.

The rotor rpm drops comparable to the engine rpm drop. I am sure if I push it harder the engine would stall.

I have a 30' head and pushing it hard I might make 3 mph.

I don't have the manual in front of me but I believe the high idle at max. is 2440. Should I adjust it to 2520IJ

Please explain " the pump is getting two turns ". How do you adjust thisIJ

before turning the fuelpump etc. i would mount a turbo gauge to measure the pressure in the intakemanifold. I had a 1460 and the intake pressure should be 1,2-1,3 bar max with new fuel, and airfilter on that but i dont know on the 1688.

Piston, there is a cap on the back end of the injector pump, you will lose a little engine oil when you remove it. Under the cap is a lock nut that takes a 10mm wrench turn the screw in to increase fuel. I've been told that one full turn is approxamately 20 hp. I don't want to increase rpm because that increases the speed of everything on the machine including the shoe which has enough troubles at rated speed. Maybe one should check the boost pressure as stated aboveIJ I am going to try turning the screw on mine!

Our manual says 2500 to 2540, I believe. I know that when we first had it it was not set that high, and I noticed a difference when we did set it correctly. That being said, 3mph in 60 bushel wheat with a 30 foot header is probably about right. The thing with those john deeres is that if you open the concave a little bit you can really shove the crop through without a horsepower issue. However, I hope this is not YOUR crop that he is harvesting, because he is DEFINITElY throwing quite a bit of grain over. The thing about an axial flow is that if you have it set correctly, the engine HP, rotor capacity, etc. WIll NOT allow you to throw over!

to save power i would set the concave at 1 and run the rotor as slow as possible just a litle faster than the point where kernnels gets out untresched in the heads.

1688 should easily be able to keep up with a 9500 ours runs equal if not better the the 9600