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Author Topic: *POP* from the carbs on acceleration  (Read 1340 times)

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Offline Industrial Cafe

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*POP* from the carbs on acceleration
« on: April 15, 2009, 11:23:36 AM »
every once in a while. I get a little POP from the carbs when I start off from the light.
I assume it's ignition timing, but I want some opinions.
    It's a cb750K8, I have dyna ignition and the plate is turned all the way clockwise. I'm unsure if thats advanced or retarded. there's no markings to tell me.
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Offline torrinh

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Re: *POP* from the carbs on acceleration
« Reply #1 on: April 15, 2009, 11:27:44 AM »
Why don't you just get a timing light and get it tuned? All the way clockwise is probably not correct. I have a dyna-s with plenty of room to adjust either way.
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Offline Industrial Cafe

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Re: *POP* from the carbs on acceleration
« Reply #2 on: April 15, 2009, 11:53:54 AM »
my timing light is broken, I'll have to borrow one. still i need to know which way is advance.
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Offline TwoTired

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Re: *POP* from the carbs on acceleration
« Reply #3 on: April 15, 2009, 12:13:49 PM »
Popping in the intake is either advanced ignition timing, lean mixture, or leaking intake valves.  Which would you prefer to investigate first?
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Offline Industrial Cafe

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Re: *POP* from the carbs on acceleration
« Reply #4 on: April 15, 2009, 12:16:20 PM »
I'll take ign. timing, then mixture, then the intake valve.
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Offline Frankenkit

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Re: *POP* from the carbs on acceleration
« Reply #5 on: April 15, 2009, 12:17:59 PM »
dunno about your carbs but on mine (the PD 50s) the air cutoff valve was used to reduce/eliminate lean popping on deceleration... dunno if it'd be the same issue.
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Offline TwoTired

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Re: *POP* from the carbs on acceleration
« Reply #6 on: April 15, 2009, 12:23:38 PM »
Quote from: Kit on April 15, 2009, 12:17:59 PM
dunno about your carbs but on mine (the PD 50s) the air cutoff valve was used to reduce/eliminate lean popping on deceleration... dunno if it'd be the same issue.
No, the air cutoff circuit is to prevent the >exhaust< lean popping on deceleration.  It cuts off the oxygen needed to sustain fuel burn in the exhaust.

Cheers,
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Offline timdhawk

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Re: *POP* from the carbs on acceleration
« Reply #7 on: April 15, 2009, 03:35:56 PM »
IC, do you not have the instructions for the Dyna? On mine you use a electronics tester light, not a designated timing light...and mine is also not all the way forward, FWIW.
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Offline Industrial Cafe

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Re: *POP* from the carbs on acceleration
« Reply #8 on: April 15, 2009, 04:09:09 PM »
I do not have the instructions. it was on the bike when i got it.
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everything I say is pure speculation and
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Offline eurban

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Re: *POP* from the carbs on acceleration
« Reply #9 on: April 15, 2009, 04:45:20 PM »
Dyna recommends setting the timing at full advance and using the advance timing marks.  Do it correctly; get a timing light.  Probably not wise to ride much until you do.
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Offline Industrial Cafe

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Re: *POP* from the carbs on acceleration
« Reply #10 on: April 15, 2009, 05:07:37 PM »
AH-HAAA! fixed it! there was a tight intake valve on cylinder 2!
thanks for all the help.

thanks TwoTired!
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everything I say is pure speculation and
I have no idea what I'm talking about  ._.

                                    Marla              .:71CB750:.CAFE
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