240D RPM's

[jimjumper]

I finally hooked up my mower (5') and drove to around for a bit to check for problems. According to the manual the mower should be running at 540 rpm's with the engine operating in the neighborhood of 2200 rpm's. In driving it around the engine was running at about 1900-2000 rpm's and everything seemed to be fine. However, the engine and throttle control maxes out at about 2000 rpm's. What is the actual max running rpm the engine should be able to achieve and is that max with or without the PTO engaged and under load? Is it possible that I just need to adjust the throttle linkage a bit to get a little more throttle throw?

 

[Neat 1500]

Possibly just needs adjustment. I can wind mine up to about 2300 with no problem.

 

[winston1]

Operation manual states full throttle speed at full load should be 2400rpm. Fast idle speed should be 2600rpm. Slow idle speed 800rpm. Working speed 1800 to 2400rpm.

Are you confident you tachometer is reading correctly? Might want to check it with something like this. Digital Photo Sensor Tachometer

 

[California]

My YM240 conforms to Winston's specs.

I have an Old School small engine mechanical tach that I've had for years.

Briggs & Stratton 19200 tachometer

You turn the dial to extend the wire out of it - similar to a tape measure.
The wire flaiils around until you have enough wire out to match the resonant frequency of the engine, then the wire becomes stable.
At that point read the rpm marks on the dial.

I've verified the tachs on three Yanmars I've owned at various times. All tested as accurate.

I like this all-mechanical device better than an electronic tach that is larger, more delicate, and has batteries that can run down or corrode. For something I might pull out of the toolbox only once in several years this is sufficient, and elegantly simple.


Added: random thought, way off-topic: Long ago I saw an old diesel truck tach that worked on this resonant frequency principle. It was mounted on the dashboard and looked like a comb with blades of various lengths. It would be easy to glance over and see you had reached the next shift point. Simple, accurate, no maintenance needed.

 

[normde2001]

Are you referring to a rotary cutter, (bush hog type mower)? If so a 5' is overloading your tractor. How many RPM with no mower attached?

 

[jimjumper]

Are you referring to a rotary cutter, (bush hog type mower)? If so a 5' is overloading your tractor. How many RPM with no mower attached?

Yeah, I know the mower is a bit big but it picks it up just fine and I'm not mowing anything heavy like grass, mostly just weeds that grow up when it rains. SoCal doesn't have much in the way of grass. i may have figured it out anyway. I went to adjust the linkage to see if i could get anymore but when I started up the tach wasn't working anyway. Took the cable off and discovered that the internal cable was broken about 3" from the end that goes into the tach. So I'll check again when I get the new cable.