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backfires on deceleration

I am gonna put new intake and exhaust seals on it this weekend along with a new stock filter. I will keep you posted.. Thanks for all your help so far. BTW it seems to run a little bit better with the choke out about 1/3. Which tells me also that its a lean condition.
 
hi ,im kinda having same problems..but heres the deal with mine.got an 05 fatboy.mods as follows.....k&n high air flo;hooker pipes long evens(no baffles);s&s510g gear cams.stage 1 download from harley(fuel inj)..............still get decelration backfire and popping between shifts,also flat power on 4th gear roll out....any suggestions.Also have NO DFO installed at this time.had a rev tech (edit ,:newsmile055:) and then a cobra neither of which did the job
 
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The stage 1 download is still very lean for your setup and without the baffles you are loosing even more. Put some baffles in it and your 4th gear roll on will be improved as well as other areas too.
 
My 07 FXST only has SEII slipons and has been retuned by the dealer but crackles and pops on decel constantly. Never had this problem before with any other HD I've owned. My 03 Ultra had a stage 1 upgrade and never a problem.

Don't know where to go from here. These new engines have all sorts of sensors and valves everywhere. I'm thinking of installing V&H bigshots to get my traditional HD sound back.
 
I had the same popping problem on my stock 08 FLSTN. I understand that this is a fairly common issue with newer HD's. After my bike's first 1000 mile service I decided to install a Zip kit from Zippers Performance. The ThunderMax tuner that comes with the Zip kit addresses this decel popping issue. The tuner has settings that you adjust to cut out the fuel on decel at specific RPM's where the popping occurs. This has 100% cured the problem. I have put 5000 + miles on the bike since I changed the ECM and I have had no problems . I am also running my bike in a closed loop with wide band oxygen sensors.
 
Hi, have an 07 fxstc with the exact same poppin and bangin. Got SE11,s fuelpac KnN filter. You will not stop these later bikes poppin at lower rpm. Friend of mine has 09 rocker c with force winder, dynojet fueller, v+h pipes and still pops identical to mine. If you want to stop the poppin buy a carb bike or dont modify the efi bike. Just live with it and enjoy the ride.
 
I have a 2006 XL1200C Sportster that runs beautifully with a rejetted carb and vance and hines short shots. It's smooth on both acceleration and deceleration.

I wanted a bigger bike, so I just bought a 2006 FXDL Lowrider with only 3,000 miles on it. It has Vance and Hines Big Shots and a Screamin Eagle air filter. It runs smooth on acceleration but vibrates horribly on deceleration and pops and backfires.

I checked all the forums I could find on the subject and have checked the motor mounts, alignment, belt tension, and just removed the primary cover and checked the primary chain. I can't find anything wrong! However, the only way to decelerate is to pull in the clutch and then the vibration disappears. It's not just a vibration in the pegs, the whole bike seems to vibrate and shudder in any gear when you back off the throttle. Could it be the EFI???? It feels like a mechanical issue.
 
chips said:
My 07 FXST only has SEII slipons and has been retuned by the dealer but crackles and pops on decel constantly. Never had this problem before with any other HD I've owned. My 03 Ultra had a stage 1 upgrade and never a problem.

Don't know where to go from here. These new engines have all sorts of sensors and valves everywhere. I'm thinking of installing V&H bigshots to get my traditional HD sound back.
Click to expand...

G'day Chips
This is my first ever forum post so here goes ...
I also have a 2007 FXST which I took delivery of in Dec 2006. This was to replace a 1990 FXSTC that I bought in 1992 and had done 227,000 kms anyway ...
I decided to run the new FXST for a while prior to doing anything to it to get to 'know' it prior to any mods. Then after 10,000 kms I had a breather kit fitted and pipes changed. I decided on the Arlen Ness Big Sucker and a set of S&S slip-on tapered shorty pipes. I also had the exhaust valve removed from the rear header pipe.
These mods made quite a difference but the bike did crackle & pop on deceleration.
Then, just before a ride from Adelaide to Perth and back, I had the 16,000 km service done and had a chat with Blair Freeth, service manager at Peter Stevens. What was happening was that the bike was running too lean. The range of self learning of the ECU for the standard factory map had been exceeded. The concern was that the engine would run too hot on the 6,000 km trip. After some discussion I decided to go with the HD EFI Race Tune Kit. This allowed the factory ECU to be remapped with one totally suited to the mods that I had done. So tune #159AE004 was loaded and the bike really did run a lot better with no deceleration issues and on the Adelaide to Perth and back road trip it ran really well. I am still currently running tune #159AE004 (but slightly modified). I have now done 45,000 kms and the bike really is running great. But you still can't ride under our radar. :s

Hope this is of some use ...

GeeJay
 
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