The Forestry Forum

Any suggestions on what the idle rpm and high rpm should be on a 24hp/3600rpm engine?

Not knowing the brand of engine and relying on my memory, low idle should be 1100-1200 rpm. Wide open throttle with no load 3,600 to 3750 rpm. 

Thanks. It is an Onan

If I'm thinking correctly, the book for the ONAN that was original on the LT40HD that I had, stated that a LOW RPM of 1800 and HI RPM of 3600 is the standard setting!

Chuck, thanks! I tried every combination of governor spring, throttle solenoid adjustments etc. and the optimal numbers I got were the numbers you referenced. 

Chuck is correct. Stationary air cooled engine carburetors don't have a power valve or accelerator pump and will stall when the throttle is suddenly opened if the idle is set too low.

Quote from: sawguy21 on April 18, 2024, 12:20:40 AMChuck is correct. Stationary air cooled engine carburetors don't have a power valve or accelerator pump and will stall when the throttle is suddenly opened if the idle is set too low. Idle speed isn't a factor as the engine is running at rated max when the clutch is engaged.

I've seen later Onan twins using a carb with accelerator pump.  When manufacturing was moved to Canada all the engines featured lean burn and accelerator pumps.  I prefer the older style carb with richer jetting and no accelerator pump, but the fuel efficiency difference is noticeable.

Idle speed isn't a factor in acceleration-load as the engine is operating at max rated speed when the clutch is engaged.