I've got my 24hp Honda set at 3500 rpm's my 27hp Kohler at 3550 w/out blades engaged. Both mowers 60 inchers. Any suggestions on the perfect rpm's?
Best RPM setting for my Super Z or any ZTR?
HenryB
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I don't know about the Honda but the Kohler can safely be run at 3600 RPM with the blades engaged.
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I think you might check your engine manual. Mine says to run the engine at full throttle whenever you're mowing as this ensures adequate cooling for the
engine and probably for the hydros too especially if fan equipped.
engine and probably for the hydros too especially if fan equipped.
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He is talking about governed engine speeds guys. Always run your mowers with the throttle lever all the way up when your blades are engaged.
Both mowers should be set at no load 3600 rpms or up to 3650. Once the blades are engaged rpms will usually be about 100 lower.
Both mowers should be set at no load 3600 rpms or up to 3650. Once the blades are engaged rpms will usually be about 100 lower.
None of the mower's I own incorporate a big Honda engine, only the small 5.5 HP engine.So I'm ignorant to where the rpm should be on a 24hp Honda.Both, Kawi and Kohler V-Twins are rated at 3800.The Kawi's on our last Exmarks were set to 3750, and Toro TurboForce Z-masters, 3830 right from the factory.We have set our Kohler's and Kawi's at 3800 since the introduction on the V-Twin engines.
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Same here... 3750-3800 RPM.6'7 330 said:
No idea on the Honda.
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You are absolutely correct the air cooled engines should be run at their recommended rpm's at all times for the cooling system of the engine and hydraulics to perform to their optimal capabilities. That is why you keep the temperature lower on the engine and pumps by running the engine at full throttle.Scotts' Yard Care said:
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I've heard this also but I've also heard that you should lower the rpm's after mowing for a few minutes to cool the engine down. As in put it to half throttle on the way to the trailer, load it and leave it running for a minute to cool off. Sounds like a contrdiction, but not sure which is right. I must admit I'm guilty of running my mowers at 2/3 throttle sometimes in tight areas or where I don't want to throw clippings as far. I think most of my yards are small enough that heat shouldn't be problem. I've also heard you should lower rpms in wet lush grass for clumping which has rarely ever been a problem for me exept on a Grasshopper.puppypaws said:
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You let a diesel idle to cool down the tubo charger, I always let my tractors run for about 5 minutes before I switch them off but your air cooled engines and hydraulic pumps are cooling best when they are running their recommended rpm's. the fans are moving more air when turning faster. When you are even in a water cooled vehicle it cools better when the fan is turning good and you are moving air faster over the radiator, some vehicles in very hot weather when they are sitting at a stop light the temperature will rise but if you put your foot on the throttle and increase the engine speed it makes the fan turn faster, you can see the temperature drop a little. You should never run your mower at lower than recommended rpm's it is hard on the components, that is not to say you can't do it for a short time and not hurt anything such as a short distance you don't want to through the clippings very far but for cool down it will actually stay warmer at half throttle and cool more at full throttle.tacoma200 said:
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Henry,
3500rpm no load is too low no matter what brand (speaking modern ZTR engines here).
You NEED to be cutting grass at no less than 3600rpm. SO....if that means setting the free load to 3800, then so be it. Whatever it takes to mow at 3600.
I believe DC was cranking their 24 Honda's at 3800. Do a search for Evan528, he had a 24 Honda DC a few years back.
3500rpm no load is too low no matter what brand (speaking modern ZTR engines here).
You NEED to be cutting grass at no less than 3600rpm. SO....if that means setting the free load to 3800, then so be it. Whatever it takes to mow at 3600.
I believe DC was cranking their 24 Honda's at 3800. Do a search for Evan528, he had a 24 Honda DC a few years back.
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Bob Stakes with Chesapeake Engines said to always run the air cooled engines at full throttle and make sure the rpm's are adjusted to the manufactures specifications. He said they would also switch off better from full throttle because it would burn the gas and fumes out so it would not try to backfire. It is designed for the fans to cool the engine and hydraulics best at full throttle, he said drive on the trailer at full throttle and switch it off. This is what I already new but I verified it with the engine rep because it sounds more official.
Hmmmm...that is why most construction equipment is designed to idle when not being used...The ones that dont will not last as long. They have plenty of cooling air at idle with no load. Heck, they must have plenty of cooling air at any RPM under load as well otherwise generators with eco throttle would not be working very well.
The engines will produce less heat at lower RPM especially with no load on them such as when you are just driving around with the blades off.
Do any of you that are going on and on about this have a temp guage with real results to back any of it up?
The engines will produce less heat at lower RPM especially with no load on them such as when you are just driving around with the blades off.
Do any of you that are going on and on about this have a temp guage with real results to back any of it up?
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ive never heard of the turning off at wide open throttle, ive never done that for any equipment, and mine backfire at just half throttle turn offs so i cant image a full throttle turn off, i always pull mine in, idle for a few seconds then turn them off.
i cut 50% of my yards at 60-75% throttle, theyre just too small to run full throttle and burn up all that gas, i only run wide open 100% on a couple large lawns.
i cut 50% of my yards at 60-75% throttle, theyre just too small to run full throttle and burn up all that gas, i only run wide open 100% on a couple large lawns.
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I thought just like you do I had never cut a engine off at full throttle either and I had two 27 hp Kohler engines on Hustler Super Z's and they would back fire no matter what I did. I called Kohler and they said "switch the power off between 3/4 and full throttle, it still backfired at 3/4 throttle so I tried full throttle and it has never backfired again. I had to know why this worked so I called them back and they told me when I switched it off at full throttle it burned all of the gas and fumes left in the carburetor and that is why yours is backfiring because it can't if all the gas and fumes are gone. The 28 efi I have now switches off and cranks perfectly in any position the throttle lever is placed. These boys will tell you should never operate hydrostatic below recommended rpm's it is hard on your pump and motors, that is what the speed control levers are for to speed up and slow down not to use the throttle to reduce the rpm's you are only shortening the life of the pump and motors.Ramairfreak98ss said:
The 1/2+ throttle shutoff is really only for Kohlers. Their anti backfire solenoid really only works on the high speed circuit of the carb. If you are running low speed and shut off it will continue sucking fuel through the low speed circuit because it does not get blocked after you cut power to the solenoid.
Most Briggs and Kawasaki carbs have the fuel solenoid located such that it cuts fuel to all passages. I honestly do not know why Kohler uses such overly complex carbs on their V-twin engines...
Most Briggs and Kawasaki carbs have the fuel solenoid located such that it cuts fuel to all passages. I honestly do not know why Kohler uses such overly complex carbs on their V-twin engines...
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It blew my mind also but Kohler explained it and once they said it did not effect the engine at all to switch it off at full throttle I left it at that because as long as it cuts off without backfiring I really don't care. I never keep one till it runs out of warranty anyway I just didn't like to hear the noise, the 28 efi is the best engine I have owned out of the Kawasaki's, Brigg's and Kohler's it cranks, cuts off, has good power, is more responsive and has a lot better fuel economy. I just wish they could get a 35 efi on the Super Z's.pugs said:
You need to set your engine at the manufacturer's recommended no load setting.......PERIOD.
If you alter that and there is failure from overheating, or bearing failure......that's on you.
As far as shutting an engine down at WOT.......no way!!!!
You kill the spark to the engine and the engine is running so fast it still continues to draw in fuel which washes lubrication off the cylinder walls........and or the fuel mix hit's hot spots and back fires.
If it's a Kohler 25, no matter what you do it will backfire!!!. Nature of that beast. Been listening to customer's complaints for years
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Good general advice. But explain to me why one ZTR manufacturer will spec an otherwise identical engine at 3600 and another at 3850? I won't even get into what the RPM's are set at when you drive it off the showroom floor.tallimeca said:
My point being, if your mowing at less than 3600, your not utilizing your optimal BTS and cooling effectiveness.
If an engine differs in speed from free load to mowing by 2-300rpm, setting at manufacturers recommended RPM may not be enough.
That would have to be proven. And, as I stated above, with the wide variances in delivered RPM settings, this could NEVER be proven.tallimeca said:
Follow my suggestion a couple posts above this....it DOES work.tallimeca said:If it's a Kohler 25, no matter what you do it will backfire!!!. Nature of that beast. Been listening to customer's complaints for years
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