Subaru 211cc Throttle Position

[rgamble]

Last year I purchased an Ariens/Gravely splitter (model 917004 -- "34 ton" with a 2-stage 13 GPM pump) with a Subaru 211cc motor to supplement a 15 year old splitter with a non adjustable throttle.

The manual specifies running at full throttle (3750 rpm) whereas it gets the job done at about 75% even with really large pieces requiring vertical operation.

If any of you have any experience and/or insight regarding throttle setting I'd be really interested in learning more.

Thanks -- Rick

 

[Jere39]

I do not know anything about your specific application, but, in general, most small engines are designed to run at WOT, wide-open-throttle. Their design relies on the cooling, oil distribution, and hydro pump efficiency that results at that speed. As you have observed, your engine, and most lawn tractor engines for instance can function at lower throttle setting. I'd run it up to the design spec.

 

[CaseyForrest]

All you are doing by running part throttle is lowering the psi the pump will produce. You are also taking the engine outside it's optimum power band.

 

[greenskeeper]

FWIW I've always run my circa 2000 Huskee log splitter just above idle (about 25% throttle) for the majority of my splits. Once in a while I'll bump it up but I've had no problems with anything on the splitter going on 15+ years.

 

[nathon918]

All you are doing by running part throttle is lowering the psi the pump will produce. You are also taking the engine outside it's optimum power band.

lower RPM's will only decrease the flow of the pump, not the pressure...it may take a second longer to build the pressure but it will build it...
as for power band...the max rpm isn't typically where it make the most HP or torque...I would bet the splitter manufacturer suggests the full throttle speed to get the rated cycle speed out of the machine, not for getting max HP out of the engine...

to the OP...it really doesn't matter what speed you run it at...its air cooled, and the flywheel is always blowing air across the cylinder, (lower rpm=less air, but also= less heat), oiling...splash type oiling still moves plenty of oil around at idle, if its pressurized oiling its even better... it really doesn't matter what speed you run it at, most speed recommendations are from the equipment manufacturer, not the engine manufacturer.
many old small engines without an adjustable throttle came with a governor rod/lever that had a series of holes and each hole for a different rpm, and the equipment manufacture would put the spring/linkage in the hole that would set the desired rpm for whatever the engine was running... heres a pic of the setting chart for those

 

[rgamble]

Thanks all for the tips. My thinking on this sprang from two sources. One, being wear & tear based on higher RPM. And second, I use non-ethanol fuel which is more expensive than pump gas.