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Popping on decceleration
- Archiddeon
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21 Aug 2012 23:56 #544004
by Archiddeon
1983 GPz 550
1985 Honda CH150 Scooter
1995 Suzuki GS500E
Popping on decceleration was created by Archiddeon
Hi all,
When deccelerating in gear my bike makes a bit of a muffled popping / pffft'ing sound. Otherwise she runs well, idles smoothly and good throttle response.
Is this normal (I know some cars are supposed to make these sounds, but not sure about bikes)? Is it bad? Would it be due to carbs being unbalanced or perhaps too rich (too much unburnt fuel entering the exhaust)?
Thanks!
When deccelerating in gear my bike makes a bit of a muffled popping / pffft'ing sound. Otherwise she runs well, idles smoothly and good throttle response.
Is this normal (I know some cars are supposed to make these sounds, but not sure about bikes)? Is it bad? Would it be due to carbs being unbalanced or perhaps too rich (too much unburnt fuel entering the exhaust)?
Thanks!
1983 GPz 550
1985 Honda CH150 Scooter
1995 Suzuki GS500E
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- MFolks
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22 Aug 2012 00:26 #544008
by MFolks
1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
Replied by MFolks on topic Popping on decceleration
I'd look for vacuum leaks:
1.The carb boots(the rubber ducting from the air filter to the carbs).
2.The carb holders(between the engine and carbs).
3.The rubber sync plugs on the carb holders,looking for cracks
4.If you have the vacuum operated petcock,inspect the rubber diaphram for holes,and tears. Check all related rubber lines for cracks.
Also watch this:
(Using An UNLIT Propane Torch For Vacuum Leaks)
If no rubber cracks found,how's the valve clearances look? Too tight of a clearance will expand when hot, possibly causing your noise.
1.The carb boots(the rubber ducting from the air filter to the carbs).
2.The carb holders(between the engine and carbs).
3.The rubber sync plugs on the carb holders,looking for cracks
4.If you have the vacuum operated petcock,inspect the rubber diaphram for holes,and tears. Check all related rubber lines for cracks.
Also watch this:
(Using An UNLIT Propane Torch For Vacuum Leaks)
If no rubber cracks found,how's the valve clearances look? Too tight of a clearance will expand when hot, possibly causing your noise.
1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
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- Polar_Bus
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22 Aug 2012 09:52 - 22 Aug 2012 09:54 #544055
by Polar_Bus
Bikes:
'84 GPz1100
'06 HD Fatboy
Replied by Polar_Bus on topic Popping on decceleration
Also you might have an exhaust leak. The header flanges, or a small rust hole can cause the exhaust to suck some air on decell and cause some poping. Could also be simply your pilot jets are a tad lean. If you have stock pilot jets and you have an aftermarket 4-1 exhaust and or pods this might be the issue.
Bikes:
'84 GPz1100
'06 HD Fatboy
Last edit: 22 Aug 2012 09:54 by Polar_Bus.
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- damarble
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22 Aug 2012 11:47 #544076
by damarble
I had ridiculous popping and discovered the vacuum line on the petcock had fallen off! (Hence why it would only run in "Prime".)
Go green, buy a Kawasaki!
82 KZ750M CSR Build Thread
89 ZX600C Streetfighter
Replied by damarble on topic Popping on decceleration
MFolks wrote: I'd look for vacuum leaks:
4.If you have the vacuum operated petcock,inspect the rubber diaphram for holes,and tears. Check all related rubber lines for cracks.
I had ridiculous popping and discovered the vacuum line on the petcock had fallen off! (Hence why it would only run in "Prime".)
Go green, buy a Kawasaki!
82 KZ750M CSR Build Thread
89 ZX600C Streetfighter
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- Archiddeon
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23 Aug 2012 03:18 #544247
by Archiddeon
1983 GPz 550
1985 Honda CH150 Scooter
1995 Suzuki GS500E
Replied by Archiddeon on topic Popping on decceleration
I just replaced the carb holders with brand new ones, so hopefully they aren't the problem. Also did the spray-it-down-with-carb-cleaner-and-listen leak test around the holders and boots. Will try again with the unlit propane torch. Will also check around the vacuum line. The previous owner connected it with a hose clamp, so that may indicate a prior leaking condition.
The exhaust is near-mint, very very little rust. The header flange bolts were a little loose, so tightened those up nicely. Running stock jets, exhaust and filter.
I'm planning on pulling the gas tank to sync the carbs with my newly constructed manometer, so will pull and strip the petcock at the same time I guess.
Thanks for all the suggestions
The exhaust is near-mint, very very little rust. The header flange bolts were a little loose, so tightened those up nicely. Running stock jets, exhaust and filter.
I'm planning on pulling the gas tank to sync the carbs with my newly constructed manometer, so will pull and strip the petcock at the same time I guess.
Thanks for all the suggestions
1983 GPz 550
1985 Honda CH150 Scooter
1995 Suzuki GS500E
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- Powerstroke_fan
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24 Aug 2012 17:06 - 24 Aug 2012 17:10 #544552
by Powerstroke_fan
1980 kz1000B4 LTD- 1327cc 9-1 comp
Ported J model head
Psp-3x cams
RS 36s
Welded MK11 crank
Back-cut MK11 trans
MTC 2 stage lock up
Stretched 4-6 over running Hayabusa rear rim with 190 rear tire
Complete frame brace kit installed
And Much Much more- SOLD
2014- ZX14R all stock for now
Replied by Powerstroke_fan on topic Popping on decceleration
Are you running pod filters?? Are you running Vaccum operated carbs? Could be emisssion ports need blocked?
1980 kz1000B4 LTD- 1327cc 9-1 comp
Ported J model head
Psp-3x cams
RS 36s
Welded MK11 crank
Back-cut MK11 trans
MTC 2 stage lock up
Stretched 4-6 over running Hayabusa rear rim with 190 rear tire
Complete frame brace kit installed
And Much Much more- SOLD
2014- ZX14R all stock for now
Last edit: 24 Aug 2012 17:10 by Powerstroke_fan.
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- Archiddeon
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24 Aug 2012 17:26 #544560
by Archiddeon
1983 GPz 550
1985 Honda CH150 Scooter
1995 Suzuki GS500E
Replied by Archiddeon on topic Popping on decceleration
Nope, no pod filters but I do have a vacuum petcock.
I pulled the tank yesterday and did a full vacuum leak test with both carb cleaner and an unlit propane torch ... no leaks found.
While I had the tank off I also synced the carbs with my homemade manometer.
Didn't notice any popping on my morning commute and bike sounds much better! Less noise and less vibration, better throttle response, faster idle (had to adjust the idle screw half way to work 'cause the bike was idling fast) and faster settling of the revs.
I wonder if the carbs being way out of sync was causing misfires or something during decceleration?
Going for a good ride tomorrow, so should be able to see if the problem is gone.
I pulled the tank yesterday and did a full vacuum leak test with both carb cleaner and an unlit propane torch ... no leaks found.
While I had the tank off I also synced the carbs with my homemade manometer.
Didn't notice any popping on my morning commute and bike sounds much better! Less noise and less vibration, better throttle response, faster idle (had to adjust the idle screw half way to work 'cause the bike was idling fast) and faster settling of the revs.
I wonder if the carbs being way out of sync was causing misfires or something during decceleration?
Going for a good ride tomorrow, so should be able to see if the problem is gone.
1983 GPz 550
1985 Honda CH150 Scooter
1995 Suzuki GS500E
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