50 hp 4 stroke will not idle under 1000 rpm

[50hpmercury]

I have a 1999 merc(yamaha power head) 4 stroke tiller.It has never idle-ed under 1000 rpm.carbs rebuilt and sync,and no luck.runs great getting 6000 rpm at wot.It will not troll down.I have heard that they are getting these motors down to 600 rpms.Is there an update on timming or what?It would be nice to get under 2.3 mph when trolling.Any people know whats up?
Thanks

 

[ret1sgrja]

Re: 50 hp 4 stroke will not idle under 1000 rpm

There is an idle rpm screw located on the bottom carburetor, turning it out should reduce your idle rpm. Which should be around 725 in forward gear. If this does not work you should probably have your carbs sync with vacuum gauges. You said they were cleaned, but by whom?

 

[50hpmercury]

Re: 50 hp 4 stroke will not idle under 1000 rpm

well, they were cleaned by me.I used an ultrasinic/with heat at my work.I took them all apart jets ect all came out.I put in new needles also.I used an vacume gage an got them all the same.it idles down to about 900 rpm but anything lower it will start to miss and die after a while.I know it says 725 rpm on the cover it should be set to but there is no way this motor would do that!could it be timing?
Thanks for the reply,any other ideas

 

[verado7]

Re: 50 hp 4 stroke will not idle under 1000 rpm

check compression - might be off .