« previous next »
Pages: [1]   Go Down

Author Topic: *POP* from the carbs on acceleration  (Read 1338 times)

0 Members and 1 Guest are viewing this topic.

Offline Industrial Cafe

  • Like a well oiled
  • Really Old Timer ...
  • *******
  • Posts: 6,372
  • [Brian] I've got something to say about that!
    • Undead Asphalt
*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.
Logged
everything I say is pure speculation and
I have no idea what I'm talking about  ._.

                                    Marla              .:71CB750:.CAFE

Offline torrinh

  • If you don't ride in the rain, you don't ride.
  • Enthusiast
  • **
  • Posts: 129
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.
Logged
1983 Kawasaki GPZ 750
1978 Honda CB750K w/ 1976 CB750F1 motor
1979 Suzuki GS550L

Offline Industrial Cafe

  • Like a well oiled
  • Really Old Timer ...
  • *******
  • Posts: 6,372
  • [Brian] I've got something to say about that!
    • Undead Asphalt
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.
Logged
everything I say is pure speculation and
I have no idea what I'm talking about  ._.

                                    Marla              .:71CB750:.CAFE

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
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?
Logged
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 Industrial Cafe

  • Like a well oiled
  • Really Old Timer ...
  • *******
  • Posts: 6,372
  • [Brian] I've got something to say about that!
    • Undead Asphalt
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.
Logged
everything I say is pure speculation and
I have no idea what I'm talking about  ._.

                                    Marla              .:71CB750:.CAFE

Offline Frankenkit

  • Industrial Strength
  • Really Old Timer ...
  • *******
  • Posts: 6,525
  • 2012 CBR250R, 72 CL350, Member #4600
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.
Logged
"Moderation in all things - especially moderation. Too much moderation is excessive. The occasional excess is all part of living the moderate life."
2012 CBR250R "Black Betty"
1980 CB650c- (sold) Delilah
1973 CL350- Lola?
Quote from: The_Crippler on July 19, 2010, 07:58:02 PM
Sweet, bubbly, Buddha - Say it ain't so!!!
Stuff for sale

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
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,
Logged
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 timdhawk

  • Hot Shot
  • ***
  • Posts: 377
  • 1978 CB750K
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.
Logged
In deeper than I should be...

Offline Industrial Cafe

  • Like a well oiled
  • Really Old Timer ...
  • *******
  • Posts: 6,372
  • [Brian] I've got something to say about that!
    • Undead Asphalt
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.
Logged
everything I say is pure speculation and
I have no idea what I'm talking about  ._.

                                    Marla              .:71CB750:.CAFE

Offline eurban

  • Master
  • *****
  • Posts: 1,625
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.
Logged

Offline Industrial Cafe

  • Like a well oiled
  • Really Old Timer ...
  • *******
  • Posts: 6,372
  • [Brian] I've got something to say about that!
    • Undead Asphalt
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!
Logged
everything I say is pure speculation and
I have no idea what I'm talking about  ._.

                                    Marla              .:71CB750:.CAFE
Pages: [1]   Go Up
« previous next »