idle adjustment screw, need help

hi, i need help with 1980 bat m-48, encarwi -25 mph carb.-idle adjustment screw wont slow down the rear wheel from spinninng to fast.

before my complete overhaul: new points/cond.i cleaned the carb. with it off the engine, i rmember turning the screw out this means the throtle valve was not inside. when i put the carb back together was the throttle valve supposed to go into place like it did or was the idle screw suppossed to be comletly turned in clockwise before installing the throttle valve? does this idle screw controll the amount off air intake only or does it work in conjunction with the throttle valve greatful to all who comment. -tim

Re: idle adjustment screw, need help

Just a couple of thoughts..

- Is the throttle cable improperly installed or adjusted, and keeping the slide from settling in the fully closed position?

- Is it possible that you installed the carb slide backwards? This is very easy to do, unless the design of the carb prevents it. This will make it run at a very high "idle".

- Is there a vacuum leak at either the carb/manifold joint, or the manifold/cylinder joint?

If it was OK before you worked on it, it's likely one of these.

Re: idle adjustment screw, need help

– Is the throttle cable improperly installed or adjusted, and keeping the slide from settling in the fully closed position?

the cable is operating fine i can still rev. while running and go back to idle (too high) when i let go of the throtle

– Is it possible that you installed the carb slide backwards? This is very easy to do, unless the design of the carb prevents it. This will make it run at a very high "idle".

it had a key way that made it go in only one way and i believe it whent all the way down, very good, i will check on this.

– Is there a vacuum leak at either the carb/manifold joint, or the manifold/cylinder joint?

the only thing i can say is the main part of the carb slides onto the port that leads to the reed valve and it has room for being pushed on further or moved back further, and i can tighten a screw to keep it in the desired spot.

i kept it in the position that apeared to be the least stress point on the throttle and choke cables.

maybe the idle screw only controls air intake, but i'm not sure. thanks -tim

Re: idle adjustment screw, need help

Don Pflueger /

sounds like you have the cable too tight.

Re: idle adjustment screw, need help

Don Pflueger /

i still say your throttle cable is adjusted too tight. sometimes the slightest bend in the cable routing can cause it to pull up on the slide. the slide only fits in one way on an encarwi, but check it anyway just for grins.

Re: idle adjustment screw, need help

maybe i did tighten the dial nut? on the throtle cable onto where it goes into the carb to tight, only becuase i thought it would loosen, with vibration of the engine. let me back it out

Re: idle adjustment screw, need help

Tim,

Attached is an exploded diagram of your Encarwi carb for reference.

From what I see, the idle screw sets the lower stop for the throttle slide; this is typical of most designs. Position of the screw should have little effect on assembly of the carb.

With the screw full-in, the throttle slide should be held slightly open. As you back the screw out, you should see the slide slowly closing. Eventually, the slide will come to rest on the carb body, and the screw will no longer have any effect. A few more turns out, and the screw will come loose and fall out, with its spring.

I do not see an "idle air screw" (mixture) on this carb; just the idle speed screw.

Also, while I don't have and Encarwi in my hands, I don't see anything in the diagram that would prevent the slide being installed backwards. This might just be a lack of detail in the diagram. Note the orientation of the slide: cutaway portion faces the intake side of the carb, not the engine side.

Hope some of this is helpful.

1114093808_encarwicarburetor.jpg

Re: idle adjustment screw, need help

Don Pflueger /

backing it out will increase idle speed.

i think we are both talking about the brass screw on the top of the carb that the throttle cable passes thru right? there is also another adjuster up on the throttle itself if i remember correctly. either way, the farther you turn them out, the faster the idle will become. it works kinda like the idle screw on the side of the carb. but you dont want to control your idle with the cable. you want the cable to be just slightly slack at idle.

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