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Discussion Starter · #1 ·
My new to me 03 DL1000 with 35,000 miles is backfiring under deceleration. It sounds as if its coming out of the exhaust and not the airbox. It idles fine and runs strong and has no skip or miss anywhere up thru the rev range. It has a PC III with unknown to me map, and stock exhaust. Im new to the world of the Vee and it almost sounds as if it may have an exhaust leak but im not sure.
 

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Check your boots from your throttle bodies... they can come loose. There's a number of posts with this type of issue where they just needed the clamps/hoses reseated and tightened.
 

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Discussion Starter · #4 ·
Check your boots from your throttle bodies... they can come loose. There's a number of posts with this type of issue where they just needed the clamps/hoses reseated and tightened.
I have seen that but all those post I read seemed to have had a poor running bike as part of the condition which I do not.
 

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Could be normal; I understand the bike is running pretty lean from the factory, but god knows what the previous owner did to the fuel map...
Does it only happen when the bike is hot or all the time?
Can you bring the bike back to stock (i.e.: remove the pc3)?
Exhaust leaks are pretty easy to find: listen around with a garden hose or a piece of vacuum tubing...
 

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I thought backfires were caused by one cylinder still receiving fuel during deceleration. Check your boots and do a TBS.
 

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I removed my pair valve, That stopped my back firing and my boot from poping off
Not sure the 03 has one, It just injects air into the pipes to burn any extra gas
mike
 

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Discussion Starter · #9 ·
I removed my pair valve, That stopped my back firing and my boot from poping off
Not sure the 03 has one, It just injects air into the pipes to burn any extra gas
mike
What did you do with the hoses when you removed it? just block them with a bolt and hose clamp?
 

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Discussion Starter · #10 ·

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Discussion Starter · #11 ·
Could be normal; I understand the bike is running pretty lean from the factory, but god knows what the previous owner did to the fuel map...
Does it only happen when the bike is hot or all the time?
Can you bring the bike back to stock (i.e.: remove the pc3)?
Exhaust leaks are pretty easy to find: listen around with a garden hose or a piece of vacuum tubing...
I think I would like to keep the PC3 but it does seem to do it when the bike is fully up to temp.
 

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If you are only having the "backfire" on deceleration you are ahead of most owners. You probably have "afterfire" ( exhaust side ). I don't think there is a need to worry about any mechanical problems. Having backfires on light acceleration is very common, and usually they can be helped with the Power Commander. Check the throttle body boots carefully for good measure and make sure the throttle bodies are in synch ( good idea anyway ) and maybe even check the throttle position sensor. Do these things before worrying about changing the map in the Power Commander.
 

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Discussion Starter · #13 ·
If you are only having the "backfire" on deceleration you are ahead of most owners. You probably have "afterfire" ( exhaust side ). I don't think there is a need to worry about any mechanical problems. Having backfires on light acceleration is very common, and usually they can be helped with the Power Commander. Check the throttle body boots carefully for good measure and make sure the throttle bodies are in synch ( good idea anyway ) and maybe even check the throttle position sensor. Do these things before worrying about changing the map in the Power Commander.
Thanks, and yes it is under deceleration only and runs fine other than that. It does not however seem to pull as hard at the higher end of the revs as I think it should. It seems to fall off at about 6500, is this normal? I'm guessing its not, I would assume as with most bikes it should pull pretty hard till at least within 500rpm's of redline. Could that be a map issue? I have no experience with a PC3 or how to remap it if I need to.
 

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you have an Air leak.
Your bike is 03 - I had the same problem. Checked the throttle body boots were seated - Yes Ok ,Checked all of the vacuum lines -Yes all seated.
went to put the manometer on to check balance and what do you know...... one of the little rubber covers on the Vacuum pipes was cracked/ perished and was letting in a little fresh air and lean(ing) the rear cylinder off. Went to the car wreckers and got a couple of near new ones. No popping. Mines K6 and Zuk rubber near heat does not last.
 

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Could be an exhaust leak. Check around the rear cylinder pipe where it goes into the exhaust system. Part number 8. Haven't heard much of this on the DLs, but TLS, TLR, and SVs are notorious for this failure.



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+1. That's exactly what failed on mine, and it caused backfiring on deceleration. The good news is you don't have to pull the manifold bolts from the head to replace this part, just drop the exhaust away from the short piece to fit the new seal.

Stick your ear up near the rear exhaust by the pipe, or use your hand around the joint to find the leak. It should be pretty noisy if it's failed.
 

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Discussion Starter · #17 ·
+1. That's exactly what failed on mine, and it caused backfiring on deceleration. The good news is you don't have to pull the manifold bolts from the head to replace this part, just drop the exhaust away from the short piece to fit the new seal.

Stick your ear up near the rear exhaust by the pipe, or use your hand around the joint to find the leak. It should be pretty noisy if it's failed.
This could very well be it as I have removed the tank to check the boots and they are fine, but it needs an air filter so im glad I checked it. The PO gave me a bag of misc. spare parts and it just happens to have 2 #8 exhaust seals :confused:
 

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If you are only having the "backfire" on deceleration you are ahead of most owners. You probably have "afterfire" ( exhaust side ).

My bike has never backfired, rumbling during decel with the Leo Vinces, that's it.
I was reading up on backfiring. It occurs in the exhaust pipes and can damage the exhaust and valves from the back side.
 

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Discussion Starter · #19 ·
My bike has never backfired, rumbling during decel with the Leo Vinces, that's it.
I was reading up on backfiring. It occurs in the exhaust pipes and can damage the exhaust and valves from the back side.
I think he was refering to DL1000 owners who are having trouble not all DL1000's.
 
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