idles really high. Can't even adjust black idle knob to resolve it

If it's broken or just needs tweaked

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Folsoml
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby Folsoml » Tue Feb 20, 2018 9:59 am

That vent should not be lower than the carbs. It should go over the top and lay across the top of the airbox.

You keep mentioning the floats. They are not doing anything to effect your idle.
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juntjoo
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Tue Feb 20, 2018 10:29 am

82" cb650 Nighthawk

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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Tue Feb 20, 2018 10:37 am

Folsoml wrote:That vent should not be lower than the carbs. It should go over the top and lay across the top of the airbox.

You keep mentioning the floats. They are not doing anything to effect your idle.


well now ya tell me! If any of them isn't working right wouldn't it cause too much fuel to enter causing the rise is rpms or no? Is that completely wrong as far as what too much fuel does? What would it do? Cause it to drown and just stall?

and sorry if I'm repeating myself but although the idle is high, with the choke in use it revs to 6krpms. so that wouldn't be due to extra fuel?

oh and thanks for the tip on the vent tube. makes sense. I rearranged for feng shui purpose. I'll undo that
82" cb650 Nighthawk

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Folsoml
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby Folsoml » Tue Feb 20, 2018 1:35 pm

It would cause it to stall.
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GeorgeSweety
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby GeorgeSweety » Tue Feb 20, 2018 2:32 pm

"sorry if I'm repeating myself but although the idle is high, with the choke in use it revs to 6krpms. so that wouldn't be due to extra fuel?"
That's what the choke does jj, it enriches the fuel to air mixture, less air means more fuel getting into the engine so it will rev higher when the engine is already warm. You should only use the choke to start and warm up the engine.

juntjoo
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Tue Feb 20, 2018 2:54 pm

I think I got it. 92.65% sure I do. But feel free to guess before I reveal. Gotta fix it first tho...
82" cb650 Nighthawk

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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Tue Feb 20, 2018 3:18 pm

okay, i dont want to kill anyone with suspense so here it is:

it's the fast speed idle linkage, the one bendable arm, if adjusted too close to the throttle it will open it too much. I adjusted mine to the book, stupid book. it was probably fine as it was.... and in reality the PO wasn't as much of a POS as I gave him credit for and this bike in the end(just about there) it didn't need new charging or ignition system components or messing with the head. Just a carb tune up, I only needed a couple o-rings from the whole kit, replace rubber from MC to calipers, pads still new from the 80's, and replace a few bolts.
82" cb650 Nighthawk

juntjoo
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Tue Feb 20, 2018 6:29 pm

oops https://imgur.com/a/fit3h

well I could've sworn before I put them. back on last time I had adjusted it correctly to whatever it was 2mm or less. hmm
82" cb650 Nighthawk

juntjoo
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Tue Feb 20, 2018 6:33 pm

actually they're only touching because of the idle knob
82" cb650 Nighthawk

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GeorgeSweety
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby GeorgeSweety » Wed Feb 21, 2018 2:29 am

juntjoo wrote:You have my bike! Is that the 650? Take her back out and fix her up and we can be best friends! Well, we can see...


:lol: You do realize that when your bike is running you will have more experience with a 650 Nighthawk than I do? Then it'll be your turn to give advice :D I have had my bike running but the starter clutch was shot, while I had the sump off to get at the starter clutch I checked if my cam chain tensioner was in the bottom slot :roll: it wasn't, so the head had to come off. Torquing the head bolts down saw two of them strip out way before the lowest values, so my only option was to take the top end off and helicoil the threads in the crank case and that's where it came to a halt about eight months ago :cry: I have never worked on the CV carbs for these bikes but I have worked on other CV type carbs :)

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Folsoml
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby Folsoml » Wed Feb 21, 2018 6:40 am

GeorgeSweety wrote:while I had the sump off to get at the starter clutch I checked if my cam chain tensioner was in the bottom slot :roll: it wasn't, so the head had to come off.


Two things I dislike about the CB650. :x On the DOHC Honda's the starter clutch is easy to get to and the cam tensioners are right there as well.
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GeorgeSweety
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby GeorgeSweety » Wed Feb 21, 2018 6:49 am

Folsoml wrote:Two things I dislike about the CB650. :x On the DOHC Honda's the starter clutch is easy to get to and the cam tensioners are right there as well.


Well I haven't had a DOHC 650 Honda yet, but I wouldn't rule anything out. Maybe the design faults are why SOHC 650's are relatively cheap..............as well as usually not working :lol:

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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Wed Feb 21, 2018 5:22 pm

GeorgeSweety wrote:
Folsoml wrote:Two things I dislike about the CB650. :x On the DOHC Honda's the starter clutch is easy to get to and the cam tensioners are right there as well.


Well I haven't had a DOHC 650 Honda yet, but I wouldn't rule anything out. Maybe the design faults are why SOHC 650's are relatively cheap..............as well as usually not working :lol:


hey! don't insult my new Betty. granted she comes with a couple moles one has a hair but anyway the adjustment is so dang fussy and the book is too low. I'm about to redo it to higher than 1mm, like 1.4. I show the slight difference in a tiny wiggle of the throttle, in case anyone else is as amazed as I am how these things work, in the video. trying to get something out of all this pain. but I'm really good at taking these things out now lol. anyway, unless there might be something else I am pretty sure it just needs to be adjusted a bit again. i can hear those japanese engineers snickering, or it was just the last guy to sign it off he removed the brilliant little 1.5 inch vertical handle to that adjustment arm that would have prevented thousands of domestic abuse cases from happening

https://youtu.be/0Ie_O0shVEo
82" cb650 Nighthawk

juntjoo
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Re: idles really high. Can't even adjust black idle knob to resolve it

Postby juntjoo » Wed Feb 21, 2018 6:07 pm

actually, what confuses me is the gradual climb. Is that normal choke function? If not then maybe I'm chasing the wrong guy?

And keep in mind when I simulate a good amount of throttle movement (with the throttle, not choke) I'm doing it without even using the choke. so I'm not quite sure on this one
82" cb650 Nighthawk


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