Dang cough
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Road Captain
Joined: May 2012
Posts: 603
Likes: 8
From: Ct
Dang cough
Well almost dropped the bike last night because I get a cough sometimes starting from a stand still. At a red light and had to make a right a tight right and went to take off and it coughed and damn near dropped it. good thing my right leg didn't give out, had to take like 2-3 steps to keep it upright. That was a close one. What causes the bike to cough when taking off?
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
lean fuel mixture
advanced ignition timing
valve not closing fully ( bent valve, burned/worn seat, cam timing, lifter, pushrod adjustment) this is far less likely
you don't say which year bike you have.
the CV carb did this for the 18 years it was available...a quick and easy mod would solve it
if you have EFI and a "tuner", then you may be able to adjust fuel/spark timing
the twin cam doesn't have much of a flywheel, there is little forward momentum stored- so you may need to get in the habit of more throttle when you take off
mike
advanced ignition timing
valve not closing fully ( bent valve, burned/worn seat, cam timing, lifter, pushrod adjustment) this is far less likely
you don't say which year bike you have.
the CV carb did this for the 18 years it was available...a quick and easy mod would solve it
if you have EFI and a "tuner", then you may be able to adjust fuel/spark timing
the twin cam doesn't have much of a flywheel, there is little forward momentum stored- so you may need to get in the habit of more throttle when you take off
mike
Outstanding HDF Member
Joined: May 2008
Posts: 2,543
Likes: 19
From: Ashland Ohio
Has it always done this? Then it's most likely tune related. Has the bike been tuned? PC3?
If you used the SERT to tune it? Try Lowering the AE, coff from start is actually too rich most of the time with EFI. Bike gets dialed in, and the changing AE to match is forgotten.
What MK said if you have a FuelPak.
Or... did this coff thing start recently? What was done to the bike just prior to it doing this? Anything at all? Hmmmmm.... 2006... if it just started, you may wish to look at the wires that go to the injectors. Are they really tight, with NO wiggle room? Could be getting a short when the weight transfer hits the bike and rocks the engine? Worth a look. If they are really tight, pull the tank and cut back the loom a bit to loosen those wires up and tape all the newly exposed wires, too. (fix a possible short).
As always, when dealing with older EFI... clean the IAC first and eliminate that as an issue. Stuck IAC would lean it out for sure.
If you used the SERT to tune it? Try Lowering the AE, coff from start is actually too rich most of the time with EFI. Bike gets dialed in, and the changing AE to match is forgotten.
What MK said if you have a FuelPak.
Or... did this coff thing start recently? What was done to the bike just prior to it doing this? Anything at all? Hmmmmm.... 2006... if it just started, you may wish to look at the wires that go to the injectors. Are they really tight, with NO wiggle room? Could be getting a short when the weight transfer hits the bike and rocks the engine? Worth a look. If they are really tight, pull the tank and cut back the loom a bit to loosen those wires up and tape all the newly exposed wires, too. (fix a possible short).
As always, when dealing with older EFI... clean the IAC first and eliminate that as an issue. Stuck IAC would lean it out for sure.
Last edited by wurk_truk; Jun 9, 2014 at 01:50 PM.
Thread Starter
|
Road Captain
Joined: May 2012
Posts: 603
Likes: 8
From: Ct
Has it always done this? Then it's most likely tune related. Has the bike been tuned? PC3?
If you used the SERT to tune it? Try Lowering the AE, coff from start is actually too rich most of the time with EFI. Bike gets dialed in, and the changing AE to match is forgotten.
What MK said if you have a FuelPak.
Or... did this coff thing start recently? What was done to the bike just prior to it doing this? Anything at all? Hmmmmm.... 2006... if it just started, you may wish to look at the wires that go to the injectors. Are they really tight, with NO wiggle room? Could be getting a short when the weight transfer hits the bike and rocks the engine? Worth a look. If they are really tight, pull the tank and cut back the loom a bit to loosen those wires up and tape all the newly exposed wires, too. (fix a possible short).
As always, when dealing with older EFI... clean the IAC first and eliminate that as an issue. Stuck IAC would lean it out for sure.
If you used the SERT to tune it? Try Lowering the AE, coff from start is actually too rich most of the time with EFI. Bike gets dialed in, and the changing AE to match is forgotten.
What MK said if you have a FuelPak.
Or... did this coff thing start recently? What was done to the bike just prior to it doing this? Anything at all? Hmmmmm.... 2006... if it just started, you may wish to look at the wires that go to the injectors. Are they really tight, with NO wiggle room? Could be getting a short when the weight transfer hits the bike and rocks the engine? Worth a look. If they are really tight, pull the tank and cut back the loom a bit to loosen those wires up and tape all the newly exposed wires, too. (fix a possible short).
As always, when dealing with older EFI... clean the IAC first and eliminate that as an issue. Stuck IAC would lean it out for sure.
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Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
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From: Phoenix '53, '88, '09 Big Twins
it can alter fuel delivery and spark timing- which is pertinent to the discussion- I think it falls into the category of "tuner"
please elaborate.
mike
please elaborate.
mike
Last edited by mkguitar; Jun 10, 2014 at 08:04 PM.