I'm pretty sure #1 speed is 540 rpm and #4 is 1000 rpm, both at a given engine speed of around 2400 RPMs. The other two are in between somewhere, not for sure what though. I've used both #1 and #2 speeds with my Yanmar tiller (tractor: TS1610F). Anything faster is not necessary or desirable.[/QUOTE
Thank you for your answer. I was guessing that #1 was 540 as it seems about that speed. #2 works well with my brush cutter for mowing down weeds and tall grass when I run at 2,000 RPM in 3rd gear M (of the H,M,L shifter). If the going gets tough, branches and the like, I shift to #1 and shift to a lower forward gear. I'm not sure what I would ever use #3 and #4 for since they are faster and most implements are rated for 540 PTO speed.
Jim