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Author Topic: Rebuilt a carb for my 73 500K2, and there be dragons  (Read 1041 times)

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Offline cshanek

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Rebuilt a carb for my 73 500K2, and there be dragons
« on: June 28, 2018, 08:42:42 pm »
Good evening,

I have a 1973 CB500K2 that recently had a pretty serious leak coming from my stock carb #2. I bought a carb-rebuild kit, and assembled and installed everything, and the fuel leak stop. Since then I have had difficulty getting her to run consistently. Below are the symptoms.

  • She will only start and run/idle with the choke on all the way
  • With the exception of one time, the second I shut the choke off she dies
  • Light white smoke coming out of pipes
  • Though both pipes are warm the port side pipe seems significantly hotter (carb #1 and carb #2 side)
  • I have tried to adjust the fuel-air mixture screws and any adjustment in any direction seems to make things worse
  • She will cough and sputter a bit at times, almost like a muted backfire. This does not occur regularly
  • I have not played with the throttle screw yet (I read that this sometimes makes a difference even when not at idle?)


Other than bad fuel and a vac leak, what should I be looking at?

Thanks,
Shane
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Offline HondaMan

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Re: Rebuilt a carb for my 73 500K2, and there be dragons
« Reply #1 on: June 28, 2018, 08:51:44 pm »
Start with the sparkplugs? They should be NGK D7E or ND X22ES-U types. It sounds a lot like they are fouled.
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Offline TwoTired

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Re: Rebuilt a carb for my 73 500K2, and there be dragons
« Reply #2 on: June 28, 2018, 09:00:25 pm »
Because this issue came up before, I must ask how you operate the choke.  You know that lever up is choke on and lever down is choke off, right? 

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
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Offline cshanek

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Re: Rebuilt a carb for my 73 500K2, and there be dragons
« Reply #3 on: June 28, 2018, 09:01:22 pm »
Correct. Normal operation = choke down, she currently only runs with lever up.
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Offline TwoTired

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Re: Rebuilt a carb for my 73 500K2, and there be dragons
« Reply #4 on: June 28, 2018, 09:06:23 pm »
Quote from: cshanek on June 28, 2018, 09:01:22 pm
Correct. Normal operation = choke down, she currently only runs with lever up.

I'd be suspicious of the pilot circuits, or low fuel level with the selector on normal feed.  Have you tried reserve?

There is a main idle screw on the carbs.  Tried that?  The screw under the grip is just a twist tension adjuster.

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 cshanek

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Re: Rebuilt a carb for my 73 500K2, and there be dragons
« Reply #5 on: June 28, 2018, 09:08:30 pm »
I have tried the main idle screw, have not tried the reserve, will look at the pilot circuits.
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Offline cshanek

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Re: Rebuilt a carb for my 73 500K2, and there be dragons
« Reply #6 on: June 28, 2018, 09:08:50 pm »
Oh and thanks for the input.
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Offline cshanek

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Re: Rebuilt a carb for my 73 500K2, and there be dragons
« Reply #7 on: June 28, 2018, 09:09:40 pm »
Thanks for the feedback, I will check the plugs. They were in good shape before the carb rebuild, who knows now.
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