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Old 03-24-2012, 08:39 AM
sharpshooter08 sharpshooter08 is offline
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Default exhaust popping and backfiring

i just bought a '02 dyna super glide carbureted with screamin eagle pipes. the bike came from Colorado but i live in Ohio and was wondering if the difference in elevation would cause the bike to pop or backfire on decelleration? do i need to rejet? thanks in advance.
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Old 03-24-2012, 10:02 AM
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Old 03-24-2012, 10:52 AM
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Originally Posted by sharpshooter08 View Post
i just bought a '02 dyna super glide carbureted with screamin eagle pipes. the bike came from Colorado but i live in Ohio and was wondering if the difference in elevation would cause the bike to pop or backfire on decelleration? do i need to rejet? thanks in advance.
First thing to do is check for exhaust leaks. Change exhasut gaskets to SE stainless steel, retorque exhaust flange nuts and pull mufflers and reinstall with some hi-temp RTV sealant. Your are about 4000 feet below in elevation. As you go lower the air is MORE dense therefore MORE fuel is required. Adjust the air bleed first and if not sufficient then you will required LARGER jets. It is possible to calculate the density effcts and determine the required percentage change, but a lot of math involved. Focus on the A/F adjustment and the pilot which control idle up to about 60mph. You might need a larger main but that's a WFO test and you need to get the A/F and pilot right first.

The stock CV carb generally "immune" or self adjusting due to the effect of air density on the movment on the slide.

Last edited by djl; 03-24-2012 at 11:03 AM..
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Old 03-24-2012, 11:47 AM
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I lived in Colorado for a few months, my carbed cars would show the effects of the mile high city air or lack of. I agree, check the other stuff then you may well have to change your jetting.
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Old 03-24-2012, 06:22 PM
sharpshooter08 sharpshooter08 is offline
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thanks everyone for your quick response. big help. i changed both jets and it runs so much better. still a little popping every now and than but i heard thats normal but still backfires now and than.
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Old 03-25-2012, 12:05 PM
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I had continuous issue with what you are describing with my 94 EVO and stock CV carb. I sent it to Killer Motorcycle and it came back with large changes--at least I thought--in jetting. From a 165 main to a 190, and 42 to 48 idle/slow jet. Plus, for $189 Dale rebuilt it entirely. The bike runs better than it ever has, and all backfiring/popping is gone.

Just to mention, BEFORE I did this, I had changed out intake seal, changed out exhaust seals, made sure everything was tight. But the leaning out of the bike and backfiring/popping on deceleration continued. You can change these jets out yourself. Piece of cake.

Lastely, since I got the carb back from Dale, I've gone to Wiseco 10.1 pistons, Andrews EV27 cam, and the bike still runs super, plugs look perfect, and I'm getter BETTER gas mileage.
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Old 03-25-2012, 02:30 PM
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Originally Posted by sharpshooter08 View Post
thanks everyone for your quick response. big help. i changed both jets and it runs so much better. still a little popping every now and than but i heard thats normal but still backfires now and than.
We set up a friends bike that came from Ft Collins this winter. It required re-jetting, along with a good tune to run well at sea level. If you're still backfiring through the exhaust, you've likely got an exhaust leak somewhere. Check the header to flange, and the header to muffler junctions. I like to use a hi-temp copper sealant at the header to muffler joint to ensure a good seal. I don't think any backfiring or loud popping should be considered normal.
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Old 03-25-2012, 02:30 PM
 
 
 
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alot, backfire, backfires, backfiring, causing, changed, exhaust, gasket, harley, intake, leak, panhead, popping, shovelhead, vrsc


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