Idle mixture and idle speed screw un responsive

[yomumsbum]

Gday everyone, I have a 1979 troopy with a 2f. Im trying to give her a tune up using the lean drop method however, ive run into a couple of issues.
So i unscrew the mixture scew 1 1/2 turns out from fully in. And screw in the speed screw so its making contact and gives me a bit of room to loosen it.
When i start up the car my multimetre says its idling around 1400 rpm, i try to lower it by loosening the idle speed screw but absolutely no change in RPM, however it does respond to being screwed in. There mixture screw also makes no difference, screwing it in or out the revs only fluctuate by 50-100 revs.
What is going on?
Thank you

 

[B y r o n]

Maybe this information will help.

 

[Pighead]

There is probably a Fast Idle Screw as well, attached somewhere on the choke linkage.
Find it, back it off a bit.

 

[yomumsbum]

Maybe this information will help.

No unfortunately not.

 

[yomumsbum]

There is probably a Fast Idle Screw as well, attached somewhere on the choke linkage.
Find it, back it off a bit.

yes there is, ive done that, but shouldnt this only have an effect with the choke on/ pulled out.

 

[Pighead]

yes there is, ive done that, but shouldnt this only have an effect with the choke on/ pulled out.

Not if that screw is still reacting with the other linkages. Back the screw out until it's not touching anything, you can turn it back in later.

 

[yomumsbum]

Not if that screw is still reacting with the other linkages. Back the screw out until it's not touching anything, you can turn it back in later.

Yeah, its no where near touching

 

[Pighead]

Ok, can you lower the idle by retarding the timing?

 

[yomumsbum]

Ok, can you lower the idle by retarding the timing?

thanks ill give that a crack, i was trying to get the correct rpm first the manual says to do the timing at 650 odd rpm. but ill give it a shot

 

[yomumsbum]

Not if that screw is still reacting with the other linkages. Back the screw out until it's not touching anything, you can turn it back in later.

yeah that got the revs down but i dont understand how that solves my problem sorry.

 

[yomumsbum]

Ok, can you lower the idle by retarding the timing?

i got it down to 900, the idle speed screw still did nothing and same with mixture screw

 

[middlecalf]

Is your throttle plate closed when not running? If not then your bypassing all the idle adjustment effects.

 

[trainbufftony]

Got slack in the cable or linkage?

 

[charliemeyer007]

Count the turns as you remove the screws, then use the p tube on a can of carb cleaner to flush out the passage. Inspect the nose of the screw for damage from someone really cranking it down which also can damage the seat.

 

[mattressking]

First make sure the primary and secondary butterfly are completely closed like @middlecalf said.

Also make sure you're using the correct screws. There are 3 for a '79 without A/C. Make sure your throttle positioner isn't holding up the primary throttle shaft, so back that off completely.

 

[roadstr6]

I've had a situation before where a paper carb gasket was interfering with the secondary butterfly and not allowing it to fully close. That allowed the carb to pull fuel from the secondary and bypassed the idle circuit. First things first...check that your idle solenoid is working properly and that it clicks when 12v is applied. Once you determine that, look real closely at the butterflies and make 100 percent sure they are closed. I think those checks are a good place to start.

 

[yomumsbum]

So my accelerator cable doesnt return all the way unless i push it by hand, however i cant make out what is holding it up, both idle speed and fast idle screws are loose to the point they are about to come out

 

[yomumsbum]

looking in the carb both the butterflies are closed

 

[yomumsbum]

my dwell angle is 39 degrees if that matters

 

[charliemeyer007]

Maybe the cable is fraying inside. I have a Yamaha cable luber from the 70's. The p tube from a can of WD40 will plug in and you can flush the cable housing, then use cable lube.

Amoron has a knock off for $12

https://www.amazon.com/Universal-Motorcycle-Lubricator-Throttle-Clutch/dp/B071RRY18Q