popping on deceleration ( low to idle)
#21
09-24-2012 | 02:08 PM
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Road Captain
Joined: Jun 2010
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From: New Jersey Somerset
Yes, popping is fumes being burned in the pipe. It is caused by unburned fuel igniting in the exhaust, however it can be a result of both lean and rich tuning. Without a dyno you really have no clue what your mixture is.
Also, the burn rate is the same no matter if it is lean or rich.
Also, the burn rate is the same no matter if it is lean or rich.
#22
09-24-2012 | 02:17 PM
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Road Captain
Joined: Jun 2010
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From: New Jersey Somerset
So 1gallon of gas contains the same volume of octane as 1quart? Hm, your pretty smart...More gas means more octane...so if I add more fuel to air, then maybe it should help the burn rate... am i right or wrong? Help me out and stop PMSing
#25
09-24-2012 | 02:23 PM
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Road Captain
Joined: Jun 2010
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From: New Jersey Somerset
By the way you talk, you seem like you know and understand what you are doing. How about you help me out? I thought this was hdforums.com not drama.com man. Talk about growing up
#26
09-24-2012 | 02:25 PM
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Road Captain
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From: New Jersey Somerset
Ding! Ding! Ding! We have a winner. A good way to look at this is not that you're too rich or lean, but that the conditions are just right for unburned fuel to ignite when it hits the hot exhaust pipes. How does unburned fuel wind up there anyway? There is some overlap between the valves closing completely and some exhaust pipes actually can cause scavenging of the combustion chamber especially under high vacuum conditions like high rev / and no or little throttle decel. Anything that changes these "just right" conditions to less than perfect will cure the popping. That can be leaning it our or richening it up. We generally don't want to lean our bikes out as they're typically set up by HD to run too lean anyway, so most of us fix the problem by adding fuel to the mix.
On an injected bike this is pretty easy, there are custom maps for decel enleanment/enrichment, but on a carb'd bike you don't have separate jets for decel only. So you wind up making it richer....
On an injected bike this is pretty easy, there are custom maps for decel enleanment/enrichment, but on a carb'd bike you don't have separate jets for decel only. So you wind up making it richer....
#28
09-24-2012 | 02:42 PM
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Joined: Feb 2007
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From: Boynton Beach, FloriDuh
How do you plan on making it richer? Playing with the mixture screw really isn't how you get rid of decel pop.
There is a procedure for adjusting the mixture screw and it has nothing to do with correcting for decel pop.
What size pilot jet is installed? You probably need a #45.
My 04 1200 with the same Bub Jug Huggers doesn't have any decel pop.
BTW, the Bub Jug Huggers use a step tuned header, they're not like drag pipes.
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There is a procedure for adjusting the mixture screw and it has nothing to do with correcting for decel pop.
What size pilot jet is installed? You probably need a #45.
My 04 1200 with the same Bub Jug Huggers doesn't have any decel pop.
BTW, the Bub Jug Huggers use a step tuned header, they're not like drag pipes.
.
I guess reading comprehension is a problem?
#29
09-24-2012 | 02:48 PM
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Joined: Aug 2009
Posts: 3,212
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From: Columbus, Ohio, USA
Ok, time for some schooling.
Burn rate. This is going to be the same for any given fuel no matter what the tune or octane rating. It is a property of chemical composition and how it reacts during combustion. Being rich or lean won't change the actual chemistry that is required to burn a given amount of fuel with a given amount of air.
Within burn rate, you can begin to discuss flame front propagation and how that effects the completeness of combustion, but this is slightly different from (albeit dependent on) burn speed. There is a ton of other stuff to discuss, but that is beyond the scope of this conversation.
Octane rating. This is a measure of how easy it is for a fuel to self-ignite. See the wikipedia article from some in depth information about it. Essentially, this makes it so that the spark plug will ignite and burn the fuel rather than the fuel spontaneously exploding. Compression ration and combustion chamber geometry are two of the largest factors that determine an engine's required octane rating.
Burn rate. This is going to be the same for any given fuel no matter what the tune or octane rating. It is a property of chemical composition and how it reacts during combustion. Being rich or lean won't change the actual chemistry that is required to burn a given amount of fuel with a given amount of air.
Within burn rate, you can begin to discuss flame front propagation and how that effects the completeness of combustion, but this is slightly different from (albeit dependent on) burn speed. There is a ton of other stuff to discuss, but that is beyond the scope of this conversation.
Octane rating. This is a measure of how easy it is for a fuel to self-ignite. See the wikipedia article from some in depth information about it. Essentially, this makes it so that the spark plug will ignite and burn the fuel rather than the fuel spontaneously exploding. Compression ration and combustion chamber geometry are two of the largest factors that determine an engine's required octane rating.
