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[jenks]

Why do both my singles backfire on the over run.
Jenks

[Mark M]

Are you sure it's the bikes' exhaust?

REgards, Mark

[papasmurf]

Do you mean backfire or just crackle a bit? My Electra X pops and crackles a bit on the overrun, but is has backfired once because I refused to pull the clutch in when the engine died, when the plug cleared that caused a backfire that judging by the way the car following me backed off must have scorched the bonnet of his car. (My bike has an upswept exhaust.)

[jenks]

Definately exhaust,and is aloud bang rather than a crackle
Cheers

[Adrian]

Strangely enough this has been covered quite recently.



http://www.hitchcocksmotorcycles.com/vi ... orumorder=



Hope this helps.



A.

[Paulk]

Usual cause is air leak between cylinder head and exhaust pipe.

[Paulk]

Usual cause is air leak between cylinder head and exhaust pipe.

[Presto]

‘Deceleration Backfiring’ is the most common type of backfiring, occurring when the throttle is rolled-off. Backfiring on deceleration (as opposed to acceleration) may be caused by a lean fuel mixture in the pilot circuit. The mixture weakens to such a degree that it either fails to ignite consistently or burns slower. When the fuel charge burns more slowly un-burnt or partly burnt fuel charge enters the exhaust port and silencer. This un-burnt charge is then combusted by a subsequent combustion event or explodes spontaneously in the hot exhaust pipe, causing the ‘backfire’. The remedy may be to correct carburettor settings – adjust the pilot jet and air screw setting to run richer. One frequent cause nowadays is an ethanol residue build-up in the very narrow pilot jet, reducing fuel flow and resulting in a weak pilot mixture. The use of a solvent spray carb cleaner may clean the residue from the jet. Aftermarket pipes may increase backfiring if the carburetion has not been modified to compensate for the freer flow of air. If backfiring occurs during gear shifting a possible cause is a faulty exhaust gasket or seal, allowing air leaks into the exhaust system.

[devon john]

same problem ,,,, it was a bad fitting exhaust to head joint ,,,,,(loose fitting) took off got some exhaust past ,,, refitted problem solved