Idle

I have a 1981 jx 550 that when I start it the idle rpm is about 1500. When I take down the road and stop it wants to idle 2500 to 3000. I have the idle adjustment screw backed off and I put on new intake boots, between carbs and head. I have cleaned the carbs and still same results. Any ideas?

 

Hi there and welcome. You might need to give some more background information on what you've already done. Did you start by checking/adjusting your valves? When you cleaned the carbs, how thorough was it? Was it 'church of clean' and 'clunk test' clean? (search this site for excellent how-to's) Did you break them down, replace the rubber seals & bits? Bench sync, running sync, float levels? Have you vacuum checked since installing the new boots. (Propane or starting fluid will create an increase in rpms if there is a vacuum leak.)

Also, how many miles and where you live; someone might be near you and willing to help.

 

Valve clearances? have you checked the valves? My bike used to idle around 1300 RPMs, got my valves in speck now it is idling around 1050. In fact after I got the valves in speck I had to adjust my idle adjustment screw cuz the bike was idling too low and dying.

How is the vacuum line going from the petcock to the carbs? Is it in good shape?

 

-Valves in spec. (Before Vac sync.)
-Carbs clean, and slides go "clunk."
-Float levels verified using fuel and clear tube method.
-Bench sync.
-vacuum sync.

IN ORDER, leave nothing out. Otherwise you'll be at it for a while. The Mikunis on the 550s are especially finicky about their float levels.

 

Hey Nealcuda1, did you ever get this problem fixed? I am going through very similar situation now, thanks.

 

See my reply above. It applies to your issue as well.