gsinal 1 #1 Posted November 10, 2012 On my 520 hc i know you are supose to run them at full throtle but with mine when i throtler it up and it will go to about 4000 rpm then it will back off gradualy to about 3400rpm. is this normal or is is it ok at 3400rpmis is wearing out? Any opinions? Share this post Link to post Share on other sites
JackC 616 #2 Posted November 10, 2012 Not certain but 3,400 or anything over 3,000 should be fine. Maybe it is backing down from 4,000 to 3,400 due to the load on the engine? When does it go from 4,000 to 3,400 and what is the load on the engine, does it happen while you are mowing? Share this post Link to post Share on other sites
Foozerush 40 #3 Posted November 10, 2012 If the throttle lever won't stay up causing the rpm's to drop, you need to squeeze the rivit the throttle lever pivots on with vice grips, my 416-8 was doing that, squeezed rivit and solved my throttle from dropping rpm's..... Hope this fixes your problem... Super easy fix. Share this post Link to post Share on other sites
can whlvr 991 #4 Posted November 10, 2012 it shoulnt rev to 4000,maybe your governor spring is weak Share this post Link to post Share on other sites
stevebo-(Moderator) 8,060 #5 Posted November 10, 2012 I think that engine should run around 3600 wot. It does sound to me like you have a mechanical issue with the throttle and not the engine. Pull it out, drill the rivet (pivot point) out and replace it with a 1/4 inch bolt, washers and lock nut. This will allow you to adjust if needed. Good luck- Share this post Link to post Share on other sites
