Double barrel pipe
Mar 14, 2000 | 03:23 PM
#2
Pro Rider
Joined: Nov 1999
Posts: 1,538
Likes: 0
Alot of the four strokes I have seen with cam work or heavy mods do backfire a bit when letting off the throttle after hard runs... But it is not normal to be shooting serious flames out the back end.
I would check with the manufacturer of the pipe to see if your close with your jetting.How does the plug read? Black?
If the jetting is OK , then I would start looking into timing..(valves,etc.)....Unless the exhaust system you bought does not have a spark arrestor... If it is a strait through pipe...It is possible that it is normal(at least the flames)....But there should not be alot of backfiring.
I would check with the manufacturer of the pipe to see if your close with your jetting.How does the plug read? Black?
If the jetting is OK , then I would start looking into timing..(valves,etc.)....Unless the exhaust system you bought does not have a spark arrestor... If it is a strait through pipe...It is possible that it is normal(at least the flames)....But there should not be alot of backfiring.
Apr 12, 2000 | 08:51 AM
#4
Range Rover
Joined: Jul 1999
Posts: 195
Likes: 0
Richen up your air screw by turning out in 1/4 turn increments. Your running lean on that circuit. If you get more than 4 turns out and the problem is still there, then go up 1 size on your pilot jet and start the same process again.
Apr 12, 2000 | 11:37 PM
#6
Pro Rider
Joined: Aug 1999
Posts: 1,484
Likes: 0
No, no, no folks.....
Lean jetting does not cause backfire and flames on deceleration, period.
It is caused by a rich condition. A lean condition WILL cause backfire on ACCELERATION, which is a very bad condition and should be taken care of immediately.
Think about this..... Modern fuel injected cars have a deceleration routine that cuts the injector pulsewidth on deceleration for mileage and emissions reasons, which causes a lean enough condition to actually cause the engine to "die". They refire the engine at a predetermined point, or when the throttle is touched, with a little extra rich mixture so that it goes un-noticed by the operator.
With this in mind, what was the last vehicle on the road you heard backfire on deceleration, the brand new Lexus, or the old Ford pickup with a Holley, glasspacks, and reeking of unburnt fuel? Also, how would a lean condition cause flames to shoot out the exhaust???? Fire is caused by extra fuel not the lack thereof.....
If you would like a little more explanation, check out this link on: Dejanews
Lean jetting does not cause backfire and flames on deceleration, period.
It is caused by a rich condition. A lean condition WILL cause backfire on ACCELERATION, which is a very bad condition and should be taken care of immediately.
Think about this..... Modern fuel injected cars have a deceleration routine that cuts the injector pulsewidth on deceleration for mileage and emissions reasons, which causes a lean enough condition to actually cause the engine to "die". They refire the engine at a predetermined point, or when the throttle is touched, with a little extra rich mixture so that it goes un-noticed by the operator.
With this in mind, what was the last vehicle on the road you heard backfire on deceleration, the brand new Lexus, or the old Ford pickup with a Holley, glasspacks, and reeking of unburnt fuel? Also, how would a lean condition cause flames to shoot out the exhaust???? Fire is caused by extra fuel not the lack thereof.....
If you would like a little more explanation, check out this link on: Dejanews
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