jmdavidh09 33 #1 Posted October 7, 2015 I recently picked up a 1990 520-h. 755hrs, generally runs good.....but i do have an oddity to figure out:After mowing with it for two hours...Once its warm, it seems to over rev...like over 4000rpm per tach so i adjusted the throttle stop and got her down to about 3800rpm max when it over revs....but its still over revving periodically...seems to do it mostly when warm and under load, like mowing with a 60" deck.so, any thoughts? Share this post Link to post Share on other sites
Ed Kennell 35,904 #2 Posted October 7, 2015 Do a search on ONAN Governor. You should find a post or file explaining the throttle / governor set up procedure. Share this post Link to post Share on other sites
jmdavidh09 33 #3 Posted October 7, 2015 Thanks; i figured it may be governor related but i have not been into that yet. Share this post Link to post Share on other sites
boomers_influence 106 #4 Posted October 7, 2015 jmthe onan engines from about early 1986used a plastic flyball spacer. ( they probably saved about 20 cents )these are known to get loose and or break.when this happens they over rev.the original ones were steel.i do have the steel ones ava. if you end up needing oneboomers_influence@yahoo.comor call 651 437 2826 M-F 10-7 S-S 12-6 cent time.thank you. boomer ( the used onan engine parts guy,also NOS and new ) 2 Share this post Link to post Share on other sites
