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Author Topic: Not idling!  (Read 965 times)

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Offline Sething

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Not idling!
« on: February 24, 2019, 06:06:26 PM »
Is there a way to clean the jets for idling without taking the carbs completely off for my 1977 cb750k?

I have been successful in getting it started and it throttles just fine. However, when I release the throttle it dies almost immediately. I’ve studied a lot of past posts and adjusted the idle screw to a high idle, set the lean/rich screw to 1.5 turns out from seated, and made sure the floats are working. I’ve cleaned the main jets out with a tiny wire brush, and replaced the accelerator with a repair kit.  Timing seems to be fine with new Dyna electronic ignition, plugs and wires.

I’m assuming there’s something more that needs to be cleaned in order for it to idle. It sat for a while as I restored the rest of the bike so I’m guessing something’s blocked.
Are there some more tricks before I take this completely off and start dismantling it and soaking it in carb cleaner?
Thanks







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Offline BRG-BIRD

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Re: Not idling!
« Reply #1 on: February 24, 2019, 07:48:12 PM »
Surely one of the brighter souls on this forum will chime in but I’m thinking the carbs need to come out, that’s what I would do to perform a proper clean. :)
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“You are either on something or onto something.” The Comman Man

Offline TwoTired

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Re: Not idling!
« Reply #2 on: February 25, 2019, 09:12:58 AM »
77 model has PD style carbs, where the pilot jets are pressed into the carb bodies.  When plugged, they won't deliver fuel for idle.  These jets must be pulled/yanked out cleaned and then pressed back in.

If you then have throttle response issues, the accelerator pump check valves have to be cleaned or the accel pump won't behave.
These carbs were adjusted for a very lean idle for emissions reasons.  That is why it needs a good accel pump to get off idle under power.

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Sething

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Re: Not idling!
« Reply #3 on: February 25, 2019, 09:28:36 AM »
I was afraid of that. Looks like I’m pulling the carbs off. I think I saw some past posts about ways to get these out the right way without damaging them. Thank you for the response.



Honda 1977 CB750K
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Offline Sething

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Re: Not idling!
« Reply #4 on: March 17, 2019, 06:09:08 PM »
I wanted to come back to this thread and give an update. I pulled the carbs, took out the idle jets and cleaned them thoroughly. (They are pressed in and take a very slight amount of wiggling and pulling to remove them very carefully)  I re-installed the carbs back on the bike and it’s idling beautifully. So grateful for those of you who took the time to respond and to this forum in general.


Honda 1977 CB750K
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Offline BRG-BIRD

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Re: Not idling!
« Reply #5 on: March 17, 2019, 08:12:42 PM »
Excellent! Thank you for the update!
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“You are either on something or onto something.” The Comman Man
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