17 replies to this topic

[day101]

when ever i start my car or run it, it ticks over at 1,500 rpm i dont understand ive turned it down but dont change a thing and when i blip the throttle it goes down for a second or two and thats it.

[tino]

You changed the right screw? I was stupid and changed the fast idle instead of the idle at first.

Can't offer any more help than that im afraid.

[day101]

is there more than one idle on the carb, also i got 1 1/4 carb i think not a hiff 44, could the carb be f**ked

[Jimmyarm]

Assuming its a HS carb, its the large slightly recessed screw that faces 'up', at the front on the right iirc.

Make sure you adjust the idle when the engine is up to temperature as well, doing it when cold will mean you get a higher tickover once its warmed up

Edited by Jimmyarm, 21 June 2007 - 01:24 PM.

[day101]

yeah i have adjusted it when warm and it does till that rpm and thats it

[supermotolee]

sounds like an air leak check the vac advance pipe and any other holes in the inlet side of the carb...

[Jimmyarm]

yeah i have adjusted it when warm and it does till that rpm and thats it

Check the choke is set correctly too then, the idle screw should have quite a lot of effect upwards and downwards though.....

[dklawson]

Jimmyarm beat me to it.

If you're working with HS carbs, make sure each idle screw is adjusted AND when the idle won't go down any lower, be sure to check that your fast idle screw on the choke linkage isn't holding the throttle partly open. It's VERY easy to forget that the fast idle screw can hold the RPM up even with the choke off if it isn't set correctly.

[Gr4h4m]

cables not sticking is it?

[not so mini dan]

As Lee said its probably an air leak, best bet is to check the gaskets on the manifold for holes.

[day101]

deffo not a leak on it ill have a look at adjusting the idle

[dklawson]

Before leaving this subject of air leaks... why do you guys say that will raise the RPM? When I've had vacuum leaks it has caused the mixture to lean out so badly the only way to get the car to run requires full choke and even then the RPM have been low.

Do the later cars have a vacuum retard on the distributor that kicks in at idle? I can see that causing your RPM to go up if the leak is in the line to the distributor.

[Surfbluegarage]

i know this is gonna sound stupid but have you checked the tenstion on the throttle cable and that its not too tight pulling the butterfly open. ive got twin 1 1/4 sus on mine and wen i put them on i pulled the cable through the throttle linkage and tightened it up but pulled too much through and car idled at bout 1,500 then if i pull the throttle pedal up inside the car it slowed down. the weight of the peadl was pulling on the cable.. try it see it if does slow down

[supermotolee]

my old 1380 used to spit off the vac advance tube quite regularly (poor fitting hose dizzy end) and probably due to poor mixture/ignition set up it used to idle alittle higher like 2k rpm

[Jimmyarm]

Air leaks on the intake tract will normally manifest themselves as an uneven idle (i.e. going up and down) rather than just raising it, although this depends where they are (they would have to be in front of the jet/needle for it to do what the OP described).