Yep, running at full throttle, i.e. 3600 RPM. Almost guaranteed to wear out the engine in short order. Good for business.
Shortly after the warranty expires, so will the engine.
There is no reason to operate a mower at full throttle, well unless you are cutting hay. With the HP and torque of these new engines, cutting 3" high grass should be a walk in the park. If blade speed is an issue, they should just change the engine to blade ratio.
Let me ask a question, has anyone had an issue with power when cutting grass? I doubt it. You got to remember, the tractor manufactures make money selling new tractors. If you can make a tractor last 20 years, what's in it for the manufacture?
Richard
Full throttle would actually be 3350 +/- 100 rpm on the JD X500 series. They limit it but don't forget he is asking on how to fix the cut with his FACTORY setup. I had problems with my cut quality with the FACTORY setup until I ran it at almost full throttle because my mid PTO doesn't spin fast enough with the factory blades to create the lift required to pull all the grass and weeds into the blades. It isn't about power it is about lift with the crappy factory mulching blades. To reduce rpm required on my machine I scrapped the factory blades and switched to a better mulching blade that had a higher lift than the factory blades so I could run at lower rpm without missing strips and only topping weeds. I didn't like running my rpm's up near the 3000 range to get a good cut so now my optimal cutting rpm with the new blades is right around 2700 rpm but this is on my JD2305 and not a lawn tractor.
Now, if we want to turn this into an rpm engine wear discussion so the OP can understand where you are coming from in case the OP doesn't already know, we certainly can. While
I absolutely agree with Richard001 that running at 3600 rpm all the time is not a good idea for your engine that is not actually what I'm telling you to do. Let's talk about the current x500 series engine and then some engine rpm's. The X500 series engine is rated for a high idle of 3600 rpm but JD limits the rpm down to around 3350. It varies because some people have reported much lower. I've seen as low as 3180 rpm and as high as 3420 rpm reported in forums from the factory but the few results I've seen actually posted were mostly below 3350 rpm mark. This is obviously lower than the 3600 rpm high idle rating of the engine (
http://www.kawasakienginesusa.com/sites/default/files/manuals/99920-2290-01_fs651v-691v-730v_en_es_1.pdf). In other words, the X500 engine was designed to operate on the high end at 3600 rpm so the "red line" is above those rpm. You aren't "redlining" the engine when when you push it up to full throttle you are actually a good ways away from the "red line" because JD sets the high idle several hundred rpm below the max high idle rpm (not to be confused with red line which is higher than 3600 rpm). The engine is actually designed to be run at speeds up to 3600 rpm on a regular basis but you are limited to rpm's below that number. Will constantly running your engine in the 3350 rpm range shorten its life? It might but by how much or how little totally depends on how well you keep up with maintenance, make sure the oil is good, and limit the cold starts. Yes, the more actual revolutions the engine turns the more wear and tear put on it but how many revolutions does it take to cause enough wear for something to break? Well, that depends on how well the engine is built (materials used, tolerances, clearances, fit of parts,....) so who knows. There are also other things that damage engines but that discussion is better left for the experts.
Now if running things at high rpm's guarantee an early engine death then motorcycle engines and small engines would be in big trouble. Those engines run at much higher rpm than car, tractor, and mower engines. Depending on the engine type the high ilde can range from 7000 rpm up to near 15,000 rpm (Yamaha R6 14,500 rpm). I know, I know, someone is going to chime in with how many of those things last 20 years. Well, I have several items that I'm still using that were bought in the 80's without the engine being rebuilt and so does my dad. Lots of modern engines are designed to run at high rpm's and can still last a long time. Most engine damage actually occurs on cold starts and running up to high rpm's before the oil has heated up. In a well built modern engine, once the oil gets hot and everything gets lubricated, the amount of engine wear drops significantly. Now of course in older tractors/mowers they were typically set to run right up to the max rated rpm for the engine in them so you certainly wanted to avoid max throttle whenever possible. Is it better to run an engine in the sweet spot somewhere in the middle of the rpm range? Of course, but you cannot always do that. Take mine for example, to get 540 rpm on the rear pto and 2100 rpm on the mid pto I have to run the engine up to 2900 rpm. I'd love to be able to get 540 rpm on the rear pto at a much lower rpm like most of the big boy tractors but I can't. Am I worried about running my engine at 2900 rpm all the time instead of 2300 rpm? Nope, not at all because I maintain my equipment can change the fluids more often than recommended. Do I run my tractor in the 3000 rpm range? Absolutely, when I'm traveling over to my parents place I run her WOT which is 3170 rpm on a 3600 rpm rated engine. With all this said, I certainly wouldn't recommend running full throttle all the time on older equipment unless the high idle has been reduced well below engine max idle. The best practice is always to dip in and dip out as needed but back to the point. With FACTORY blades and setup, try full or near full throttle and see if that helps. If you don't like running it at full throttle then you can switch out blades.
I've already typed out too much so I'm not going to be long winded about advantages of making tractors last 20 years. Did you ever stop to wonder why they raise the prices on parts for old tractors at a steady rate or why they discontinue parts for old tractors? They do make the tractors to last so that is why they make it expensive or hard to maintain the old ones. That is how they try to price you into a new model of the same brand. I've watched the prices almost double for some of the parts on my tractor and it is only 9 years old. If my rear PTO fails I already know the tractor will get scrapped and I'll buy a new one and John Deere knows it too. :laughing:
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