520H4me 0 #1 Posted May 26, 2009 What should RPM's be on my 20HP Onan at full throttle? Where should vacuum be? RPM's on mine are about 3800/3900 and vacuum is about 5. Share this post Link to post Share on other sites
jaysmith801 0 #2 Posted May 26, 2009 should be around 3400 rpms Share this post Link to post Share on other sites
520H4me 0 #3 Posted May 26, 2009 Wonder why mine are so high. I thought 3800/3900 seemed high given that the tach only goes to 4000... Share this post Link to post Share on other sites
Just Piddling 0 #4 Posted May 27, 2009 From what I remember, the vacuum decal gauge was later changed to a horse power decal. Basically the higher the gauge the less load you have. Then again I may have it backwards. The max rpm and details can be found in the manual at the Toro site. Share this post Link to post Share on other sites
04fxdwgi 0 #5 Posted May 28, 2009 What should RPM's be on my 20HP Onan at full throttle? Where should vacuum be? RPM's on mine are about 3800/3900 and vacuum is about 5. per manual for my '93, 3600 max RPM, no load Share this post Link to post Share on other sites