?Deceleration Backfiring? is the most common backfiring that occurs when you change down and throttle off. This extract from the Virago Site explains it succinctly.
?In general, backfiring on deceleration (as opposed to acceleration) is generally caused by a lean condition in the pilot circuit. What happens is that the mixture leans out enough to where is fails to ignite consistently. This, in turn allows some un-burnt fuel to get into the exhaust pipes. Then when the engine does fire, these un-burnt gasses are ignited in the exhaust pipe, causing the backfire.
1. Idle Screw ? Can be Adjusted ?
Some folks cure backfiring by turning up the idle slightly. This is the brass knob on the end of the black flexible thing hanging out the bottom of the carb set. If you just have mild backfiring, you can try this.
2. Idle Mixture ? Can be Adjusted ?
No this is NOT the same thing as the IDLE. The Idle Screw just limits the minimum throttle when you take your hand off the throttle. The Idle Mix Screws. This actually controls the Gas/Air Mixture at Idle. For the location of the Idle Mix Screws and useful tools to turn them.
Most riders find that enriching the idle mixture by backing off the screws by 1/8 to 1/2 a turn will eliminate the popping. Enrichen as little as necessary, work in small increments, and test the results before backing out the screws another 1/8 turn.
3. Exhaust Gaskets ? Can be Replaced
These seem to be one of the most frequent cause of Backfiring Problems and an item that has been seen to fail quite often.
?Recently went to replace gasket where header pipe meets cylinder head. After pulling left header pipe I found culprit of noise, blown out header pipe to collector gasket. This was a corrugated sleeve that failed under the clamp. Replacement gasket is no longer corrugated. Added bonus was the commonly reported backfiring problem, I thought I had to live with, is now completely gone. Try this $11.00 fix if your bike is backfiring.?
VERY often you can fix the problem by simply tightening the Exhaust Header/Cylinder Clamp Nuts. Here is the RHS Upper One, RHS Lower one, LHS Lower One. You can also try tightening the Exhaust/Collector Clamp.
HERE IS A LINK WITH HEAPS OF INFO ABOUT BACKFIRING
http://www.google.com.au/search?hl=en&q=causes+of+motorbike+backfiring&btnG=Google+Search&meta=
?In general, backfiring on deceleration (as opposed to acceleration) is generally caused by a lean condition in the pilot circuit. What happens is that the mixture leans out enough to where is fails to ignite consistently. This, in turn allows some un-burnt fuel to get into the exhaust pipes. Then when the engine does fire, these un-burnt gasses are ignited in the exhaust pipe, causing the backfire.
1. Idle Screw ? Can be Adjusted ?
Some folks cure backfiring by turning up the idle slightly. This is the brass knob on the end of the black flexible thing hanging out the bottom of the carb set. If you just have mild backfiring, you can try this.
2. Idle Mixture ? Can be Adjusted ?
No this is NOT the same thing as the IDLE. The Idle Screw just limits the minimum throttle when you take your hand off the throttle. The Idle Mix Screws. This actually controls the Gas/Air Mixture at Idle. For the location of the Idle Mix Screws and useful tools to turn them.
Most riders find that enriching the idle mixture by backing off the screws by 1/8 to 1/2 a turn will eliminate the popping. Enrichen as little as necessary, work in small increments, and test the results before backing out the screws another 1/8 turn.
3. Exhaust Gaskets ? Can be Replaced
These seem to be one of the most frequent cause of Backfiring Problems and an item that has been seen to fail quite often.
?Recently went to replace gasket where header pipe meets cylinder head. After pulling left header pipe I found culprit of noise, blown out header pipe to collector gasket. This was a corrugated sleeve that failed under the clamp. Replacement gasket is no longer corrugated. Added bonus was the commonly reported backfiring problem, I thought I had to live with, is now completely gone. Try this $11.00 fix if your bike is backfiring.?
VERY often you can fix the problem by simply tightening the Exhaust Header/Cylinder Clamp Nuts. Here is the RHS Upper One, RHS Lower one, LHS Lower One. You can also try tightening the Exhaust/Collector Clamp.
HERE IS A LINK WITH HEAPS OF INFO ABOUT BACKFIRING
http://www.google.com.au/search?hl=en&q=causes+of+motorbike+backfiring&btnG=Google+Search&meta=
