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04 popping on deceleration
#551706 08/04/2014 11:51 AM
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My 04 America with TORs has always popped some on deceleration since I bought it with 30K on the odometer, but the other day on a very warm ride in traffic it backfired once or twice when I blipped the throttle at a light. I checked the SC caps and all 4 seem tight with no cracks, so I did an archive search and read to check the carb to air box rubber and remove the AI. Does an 04 even have AI? I don't see any of the tubes shown in youtube videos of AI removal on FI models.

I had previously set the idle at 1000 RPM, balanced the carbs at 3200 RPM with a home made manometer, and Gorilla taped over cracks in the air box, but haven't opened the carbs to check the jets. My exhaust pipes have a light blue/violet color about 2/3rds of the way down the bend and were that way when I bought it.

First, is the backfiring on deceleration harmful? Is bluing of the pipes an indication of anything harmful? Should I be concerned about the occasional blipping the throttle pops? I use premium 100% gas, ride conservatively, get 50 MPG, and subscribe to the "if it aint broke, don't fix it" philosophy. Any advice from the more experienced will be appreciated.

BTW, I did buy a good used replacement air box awhile back - just haven't wanted to cut into riding time taking the back end apart until bad weather.


Phil in Northwest Arkansas 04 America, Black, Corbin seat, TORs, no AI, 34K
Re: 04 popping on deceleration
philwarner #551707 08/04/2014 12:06 PM
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By the sounds of your airbox being cracked up ,I say theres a good spot to start.

Re: 04 popping on deceleration
marty #551708 08/04/2014 12:42 PM
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You're probably running stock jets with open exhaust, you're running way lean, these bikes have double sided headers so they are supposed to stay shiny, not blue.

For the popping, a temp solution is to turn out your air screws quarter turns till it stops. Check your jets.


Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken
Re: 04 popping on deceleration
MACMC #551709 08/04/2014 1:28 PM
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I unplugged the Throttle Position Sensor and the popping all but stopped on my 04 Speedmaster.


I'm built for comfort, I ain't built for speed
Re: 04 popping on deceleration
MACMC #551710 08/04/2014 3:41 PM
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Quote:

You're probably running stock jets with open exhaust, you're running way lean, these bikes have double sided headers so they are supposed to stay shiny, not blue.

For the popping, a temp solution is to turn out your air screws quarter turns till it stops. Check your jets.




By air screws do you mean what the manual calls the pilot jet screws on the bottoms of the carbs? Those look like they still have plugs in them on my carbs, and those little suckers are pretty darn deep up in there.


Phil in Northwest Arkansas 04 America, Black, Corbin seat, TORs, no AI, 34K
Re: 04 popping on deceleration
philwarner #551711 08/04/2014 4:14 PM
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Quote:

Quote:

You're probably running stock jets with open exhaust, you're running way lean, these bikes have double sided headers so they are supposed to stay shiny, not blue.

For the popping, a temp solution is to turn out your air screws quarter turns till it stops. Check your jets.




By air screws do you mean what the manual calls the pilot jet screws on the bottoms of the carbs? Those look like they still have plugs in them on my carbs, and those little suckers are pretty darn deep up in there.





BTW, I found a very good vidio at http://www.youtube.com/watch?v=Y2jaTKzK2IA on removing the AI and mine is already removed - no tubes beside the spark plug, just two plugs in the head.


Phil in Northwest Arkansas 04 America, Black, Corbin seat, TORs, no AI, 34K
Re: 04 popping on deceleration
philwarner #551712 08/04/2014 9:41 PM
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Quote:

Quote:

You're probably running stock jets with open exhaust, you're running way lean, these bikes have double sided headers so they are supposed to stay shiny, not blue.

For the popping, a temp solution is to turn out your air screws quarter turns till it stops. Check your jets.




By air screws do you mean what the manual calls the pilot jet screws on the bottoms of the carbs? Those look like they still have plugs in them on my carbs, and those little suckers are pretty darn deep up in there.




Yes


Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken
Re: 04 popping on deceleration
Scottb1966 #551713 08/05/2014 1:24 AM
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Quote:

I unplugged the Throttle Position Sensor and the popping all but stopped on my 04 Speedmaster.



Me too.


Live to love, love to live.
Re: 04 popping on deceleration
Keith #551714 08/05/2014 6:42 PM
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You normally get rid of popping on deceleration by richening things up a bit.

You stated that you have TORS on your bike. My 03 had TORS and no mods to the intake. It popped like crazy on decel. I removed the AI so it would have been just like your 04. I'm assuming the snorkels are still in place under the seat. If you leave those in place, I'd increase the main jet size from 120 (usually stock on an 03/04) to 125. If you want to remove the snorkels in the intake box, you will need at least a 132 to 135. I ran 135 main jets. I then added 2 shims to the needles and eventually switched them out to needles out of an early Thunderbird which got rid of a mid range hesitation/flat spot. Next, pull the idle adjustment screw caps and open the screws up a quarter turn at a time. You will be amazed at the increase in performance. These mods will help with decel popping. You could start with the easiest first by just adjusting the idle mixture screws but you would be missing out on the fun factor.

The second way to get rid of popping is to disconnect the Throttle Position Sensor (TPS). It is a bast--d to unplug. Do not unscrew it from the carb but unplug the three pin connector. The cable comes from the right hand carb. This change will not noticeably affect the performance of the bike but virtually get rid of the popping. If you perform a search at least 5 years ago, you will find the proof that it works.


12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
Re: 04 popping on deceleration
Gregger #551715 08/06/2014 12:53 PM
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Quote:

You normally get rid of popping on deceleration by richening things up a bit.

You stated that you have TORS on your bike. My 03 had TORS and no mods to the intake. It popped like crazy on decel. I removed the AI so it would have been just like your 04. I'm assuming the snorkels are still in place under the seat. If you leave those in place, I'd increase the main jet size from 120 (usually stock on an 03/04) to 125. If you want to remove the snorkels in the intake box, you will need at least a 132 to 135. I ran 135 main jets. I then added 2 shims to the needles and eventually switched them out to needles out of an early Thunderbird which got rid of a mid range hesitation/flat spot. Next, pull the idle adjustment screw caps and open the screws up a quarter turn at a time. You will be amazed at the increase in performance. These mods will help with decel popping. You could start with the easiest first by just adjusting the idle mixture screws but you would be missing out on the fun factor.

The second way to get rid of popping is to disconnect the Throttle Position Sensor (TPS). It is a bast--d to unplug. Do not unscrew it from the carb but unplug the three pin connector. The cable comes from the right hand carb. This change will not noticeably affect the performance of the bike but virtually get rid of the popping. If you perform a search at least 5 years ago, you will find the proof that it works.




Thanks for the reply. I do have some 125 jets I bought awhile back but haven't installed yet - perhaps it is time. I also bought an idle mixture D tool at the same time, but I'll have to look again at what I thought were the pilot screws under the carbs because the threaded recesses I saw in my mirror did not look big enough for this tool. If they are, what is the best way to get the plugs out? A drill turned by hand? Or am I looking at the wrong little threaded hole under there?

Guess I should try the TPS disconnect first; no down side to disconnecting it? Is it just an emissions thing? I can understand a value for one on an FI bike, but can't figure what it does on a carbed engine?


Phil in Northwest Arkansas 04 America, Black, Corbin seat, TORs, no AI, 34K
Re: 04 popping on deceleration
philwarner #551716 08/06/2014 5:28 PM
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I'll have to look again at what I thought were the pilot screws under the carbs because the threaded recesses I saw in my mirror did not look big enough for this tool. If they are, what is the best way to get the plugs out? A drill turned by hand? Or am I looking at the wrong little threaded hole under there?

Guess I should try the TPS disconnect first; no down side to disconnecting it? Is it just an emissions thing? I can understand a value for one on an FI bike, but can't figure what it does on a carbed engine?




Ok, my bad. I was looking the wrong thing; I see the D shaped pilot needle ends now next to the connections for the carb heaters. The other is just a threaded boss for something else.

So... the TPS connector. Looks like two "tamper proof" torx screws holding the connector on. Just remove these and pull it off?


Phil in Northwest Arkansas 04 America, Black, Corbin seat, TORs, no AI, 34K
Re: 04 popping on deceleration
philwarner #551717 08/06/2014 5:34 PM
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No, leave that in place and disconnect the plugs behind the carbs, follow the wires.

Re: 04 popping on deceleration
Gregger #551718 08/06/2014 6:41 PM
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Quote:

.... Do not unscrew it from the carb but unplug the three pin connector. The cable comes from the right hand carb.




As I already stated, do not remove from the carb but unplug the connector..... It is a pain to unplug but you can do it.

If you unscrew and remove the TPS sensor from the carb without unplugging it the bike will run like crap. CDI will think the throttle is closed and not advance the timing as needed. Unplugging the TPS puts the CDI in a full throttle mode (from what I've been told) with the appropriate advance curve being used. Popping disappears.


12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
Re: 04 popping on deceleration
Gregger #551719 08/07/2014 11:05 PM
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Quote:

Quote:

.... Do not unscrew it from the carb but unplug the three pin connector. The cable comes from the right hand carb.




As I already stated, do not remove from the carb but unplug the connector..... It is a pain to unplug but you can do it.

If you unscrew and remove the TPS sensor from the carb without unplugging it the bike will run like crap. CDI will think the throttle is closed and not advance the timing as needed. Unplugging the TPS puts the CDI in a full throttle mode (from what I've been told) with the appropriate advance curve being used. Popping disappears.



Sorry, I misunderstood the unscrew and thought the TPS must be screwed in underneath the black plastic part which I took to be a connector. Got the picture now.

So if the CDI thinks the throttle is wide open all the time it won't pop on decel? Is it changing the timing to cause the popping if it thinks the throttle is closed? I had thought the popping indicated it was too rich on decel, but is it just the opposite - too lean?

I adjusted the pilot screws 2 turns out today to see what that does. My manual says 1 1/2 turns, but I think somewhere here I read 3 turns, so I tried in between to begin with. Not sure how many turns they were before, so next ride I will see if it is any different before I try the next step.

Thanks for the advice.


Phil in Northwest Arkansas 04 America, Black, Corbin seat, TORs, no AI, 34K
Re: 04 popping on deceleration
philwarner #551720 08/08/2014 2:23 AM
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Phil, give this thread a read. I am not technical at all but I do know unplugging the TPS fixed my decel popping issue without any negative repercussions. It's a good read... http://www.bonnevilleamerica.com/forums/...part=1&vc=1


Live to love, love to live.
Re: 04 popping on deceleration
Keith #551721 08/08/2014 6:18 PM
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Quote:

Phil, give this thread a read. I am not technical at all but I do know unplugging the TPS fixed my decel popping issue without any negative repercussions. It's a good read... http://www.bonnevilleamerica.com/forums/...part=1&vc=1




Thanks, Keith. That was a very good read. I printed out the TPS adjustment at http://www.triumphtwinpower.com/tps_adjustment.php It describes the locking tab on the TPS connector and gives the spec resistance readings at closed and open throttle. If I can get mine disconnected I'll check the settings just for fun.

Interesting that some folks found a big improvement with it disconnected while a couple felt no change at all; perhaps it depends on whether the TPS was set to spec in the first place, although there were various other mods on the bikes involved.

I was also reminded seeing comments from FriarJohn just how much he is missed here; that little green bulldog and the good Friar live on in the archives and in our hearts and minds.


Phil in Northwest Arkansas 04 America, Black, Corbin seat, TORs, no AI, 34K
Re: 04 popping on deceleration
philwarner #551722 08/08/2014 11:31 PM
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John... how I miss that guy.


Live to love, love to live.

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