Topic: '82 cb650 idles around 4500-5500 rpms

[Phylyn51]

Hey all. Finally got the bike to fire with all 4 cylinders thanks and all to this valuable forum.

So it starts right up on comand when I pull the trigger, put then it starts Idling like it wants to get away. The last thing I did to it was I cleaned the carbs and put new plugs in. This is the first time I have had it up on all fours and Idling since I bought it 3 months ago. There are 2 things it could be:

1. When I cleaned the slowjets(removable on the '82 CB650) I just lightly seated them and did not screw them in all the way.
2. The throttle adjusting screw(I swear I did not mess with this while cleaning)

Help would be great, you fellas got me this far.

[Phylyn51]

Forgot to mention. Because I pulled the carbs off about 3 or 4 times, I just left the air box off the last few times to make the process easier. Would that make it Idle so high?

[Pinhead]

Leaving the airbox off would make it run pretty lean. I don't know if that would lead to your high RPM idle, but it definately isn't good unless you've jetted up quite a bit.

[dusterdude]

does it idle high when cold or after warm up or both?

[jabbadeznuts]

Pretty obvious, and it got me when I was working on my 550 this morning. How is the idle screw set? Maybe you can drop idle with it?

[Phylyn51]

Well first when I was messing with it I screwed them in all the way cause thats what it said in the clymer book I have. In that case, It would not start. The carbs were getting fuel so I guessed that the fuel was not getting to the cylinders. So I unscrewed the slow jet and screwed it back in until it lightly seated. Then I found a "Secret" section in my book just for the 1982 model. And it says after it lightly seats, turn it another 3/4th of a turn. Well, 3/4th of a turn is all the way closed.

After that last adjustment. When it's cold, I start it and it Idles around 2000-2500RPM then about 5 seconds later, 4500-5500RPM. Guess my messin' around isn't over yet huh?

[Ibsen]

If the idle speed is rising to 3500-4000 after you have started it cold, and it is running with the choke on, it is not uncommon. The choke mechanism have got a fast idle mechanism and If you push down the choke lever you can lower the idle rpm. But if the idle speed is as high as 4000 with a warm engine, you should adjust the idle speed screw (not the idle mixture screws) to lower the idle speed, and if that doesn't help, check that you have got some freeplay in the trottle cables. And since you have cleaned the carbs, you should also synchronize them.

[lrayvick]

Maybe your pos throttle cable is too tight i.e. keeping the throttle open.  You can adjust it at the handle bars.