Topic: Fast Idle adjustment - screw or nut?

[Faol]

Okay - I tend to compensate for my ignorance by taking things very, very literally. Not always a good idea. My 1979 650 is doing this kind of weird thing where I turn it on with the choke out and it sounds perfect for about four seconds, after which it begins to rev quickly up to at least 5000 rpm, at which point I shut it off because I'm freaked out. I'm thinking it might be the fast idle, and I've been trying to adjust that by the method described here and in the manuals. Herein lies the rub.

Everyone I've read talks about turning the "screw" to adjust it. On my bike there is a 7 mm nut where it seems like the fast idle adjust should be. I have trouble seeing into it, but the last time I looked it appeared that there might be a small slotted screwhead inside of the nut - is that what I should be tweaking? It may be that somewhere between 1979 and now someone just replaced the screw with a nut, although that seems kind of complicated - I mean, the logical choice would be a bolt, right? Or it may be that people are using "screw" to mean "little twisty thing that you turn either clockwise or counterclockwise", which in this case translates to "nut". Or, it may be that I've been turning the wrong thing. 

Any thoughts?

Thanks,
cb

[keiths]

I can't speak for the 650 but on my bike its a screw that goes through the linkage and rests on a flat spot. Turning the screw in should increase the idle speed.
Your bike should rev up as it warms up. Gradually back off on the choke to keep the rpm reasonable until the bike runs without the choke. When it is totally warm, adjust the idle screw. If it doesn't run off choke when its warm you may have to increase the idle or you have something else wrong.

[78_SaltLick]

is the throttle cable possibly bound up? possibly its not releasing all the way, so when you start your bike it revs way up.....

[byidesign]

If you have turned the Idle screw in too far, it will just race away with
    choke on /or off.
         back off the Idle speed screw {count the turns} about 1 turn at a time
     till you have to hold the throttle for it to start and idle. then while holding the
      throttle turn it in until it adjusts the speed.where you want it.
           If two or three turns out have made no difference,{still races away}
               return it to original position{that's why counting turns}
             check your choke/throttle/ fast idle linkages for being rusted/ or stuck.
                  Also the rubber carb booties next to engine for loosenes and/or cracks
                 a Vac leak will do that too...
                       Hope it helps
                                Bruce
                
            

[Faol]

Thanks, guys. I'll try out these suggestions when I get a chance (hopefully tonight) and let you know what I find out

[KB02]

You should be looking for a screw, not a nut. The Idle adjust screw's head looks like somekind of wierd flower, or mushroom.

Try this:
Twist the throttle while kneeling beside the bike so you can see where the throttle cables connect to the carbs. This big mushroom screw should be touching the linkage that you see. as you adjust it (in for increased idle, out for decreased) you should see the linkage move a little as well.
Once you're sure you've got it, follow the suggestions the others have outlines for you.

(I hope this isn't too remedial... I have some friends that really need that "Take me by the hand" approach, so I kinda get into it allot.)

[Faol]

Not too remedial AT ALL . . . I got home last night kind of late, thought about diving into the bike and realized that I still didn't know whether I was turning the right thing. I should get out of my office at a decent time tonight, so I'm planning to print these out and give it a shot.

Remedial GOOD!