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muz123

Best running RPM for a 60" deck

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I run 3000 RPM full throttle when mowing with my 60". The Onan p220 handles it fine. I would like to know if thats to low of an RPM to run the 60" or if its ok.

Thanks, Dave

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This is what my gauge read. Around 3000. Time for carb adjusting? 

IMG_2415.PNG.82e26ff04dfd25f39aa14be382ae04ed.PNG

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My max rpm now at full throttle is 3000. I will adjust it to 3400. 

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You want it at 3600 with the deck running, + or - 50rpm.   Running under this rpm risks overheating the engine.  They are designed to be run this way, one to make rated torque and two, to move enough air to cool them.  Basic small air cooled engine 101.  You definatly do not want to overheat an Onan, that gets expensive quickly as bad things happen.  When I set RPMs on a small engine, I shoot for about 3700ish no load.  While this is a bit overspeed, its ok.  I want to see it fall back and maintain at the 3600 range I typed above with the deck running in the shop.  Then the Gov will maintain that, or should, when the deck is working in the grass.  This will keep the engine, doesn't matter the brand or model of air cooled engine, in its power band and at proper cooling temps.   Also, do not rely on that dash gauge, get a proper tach to set engine rpms.  They sell them just for that, look like a pocket calculator or you have the Tiny Tach that B&S sells in ther parts selection.  I would use that till I know that dash tach is correct when compared to a known accurate tach.  

   Mike

Should just be a throttle stop or cable adjustment on the Onan to get her back to full power.   If you haven't done a cylinder head decarbon and valve lifter adjustment,  you need to research that ASAP, very important to the life of the Onan twin.   Mike   30+ years of small engine work

Edited by artfull dodger
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Not true. Wheel Horse wants 3400 rpm on my 1996 312-8 with M12. All the engine RPM literature I have seen is for no load RPM. Kohler and Onan both clearly defer to the equipment manufactures for engine rpm in all the literature I have seen. The last 2 Wheel Horse tractors I got were set to high. You really do not know how many RPM's you are running now. You only know what a 20+ year old lawn tractor tach shows. You need to buy a tachometer. Do not trust that 20+ year old 520 tach. Find the correct manual and read what Wheel Horse wanted for RPM. 

Edited by Searcher60
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Thanks for the help everyone!! With a little help from a digital tach the 520 is back up to 3550 rpm!! Shes got 1100 hours and is smooth. The Gov spring was on the first slot so i moved it to the 4th last hole and its great now. Believe it or not the 20+ year old tac on my 520 was pretty accurate lol. 

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Edited by muz123
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