I have a SP 12a /with a DCOE 45. I can't for the life of me get it to idle smoothly. Un-even idle that goes between 750-950 RPM.

Anything more than 1/4 throttle and it runs great. Also great on the freeway, but I cant get it to idle well. I'm using 65f9 jets but I've also tried 55f9 and 70f8. All seem to do that same thing.

I've checked plugs, dizzy, fuel pressure, trimming etc. Out of ideas! Please help.

 

I think Wacky will be able to give the definitive answer here but its probably just the
adjustment of the idle air jets screws. Also you may need to up the idle a bit as a
ported motor is going to be a bit lumpy at low rpms anyway.

I have my Dell on a stock port 12a idling @900 rpm because its gets too lumpy any
lower.

 

I've played with the idle screws quite a bit; Even at 1300 idle its lumpy.

 

is it idleing on the idle circuit? the throttle stop screw (its NOT the idle speed screw!) should be about 1/2 turn in, other wise you will be idling on the 1st transition hole, which makes the idle mixture screws useless.

http://www.tjwakeman.net/TR/WeberDCOEinfo.htm#idle

 

Not the idle speed adjust screw. I'm referring to the idle air mixture adjustment
screws. I have a Dell so I don't know the weber terminology or their exact location
to advise you.

Earth to Wacky, are you there?

 

The throttle stop screw is just about 1/2 turn in but I will check when I get home.

 

I'd also take the mixture screws out and make sure they're still intact. Some gorilla used to own my DCOE and screwed them in so tight the tip broke and was lodged in the hole.

 

I've replaced both mixture screws; They were slightly deformed by tightening too much.

 

well, have you made any headway with your idle quality since replacing them?
this is just funny.

 

I did all that before I posted here. I did check the idle speed screw, it was at 0.3 a turn. A 0.5 turn was idling at 1300-1500 RPM