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Ironhead Sportster Motorcycle Talk (1957-1985) For all those that wanna talk about Ironhead Sportster Motorcycles

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  #1  
Old 30th July 2012
73Sporte 73Sporte is offline
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Default Runs Poor

Help I have a 73 xlh at steady speeds only it lugs like a miss.
and after 50 miles or so the rear spark plug won,t fire.
but if i pull the plug wire off about 1/2 inch it will fire.
New Coil ,Plug wires ,spark plug, points and condenser.
Replaced Points and condenser ingiton system witl Mallory E-Spark Ingition system.
Rebuilt Carb.Bendex Tryed all the jets for Carb.
Ck Compresion 120psi after 4 strokes.
Did cylinder leakage test .Rear cylinder Exhaust valve slight leak
Had valve job both heads. Still have same problem.
Any advice would be aperciated.
Thanks 73 sporte
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  #2  
Old 30th July 2012
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nikki nikki is offline
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Quote:
Originally Posted by 73Sporte View Post
Help I have a 73 xlh at steady speeds only it lugs like a miss.
and after 50 miles or so the rear spark plug won,t fire.
but if i pull the plug wire off about 1/2 inch it will fire.
New Coil ,Plug wires ,spark plug, points and condenser.
Replaced Points and condenser ingiton system witl Mallory E-Spark Ingition system.
Rebuilt Carb.Bendex Tryed all the jets for Carb.
Ck Compresion 120psi after 4 strokes.
Did cylinder leakage test .Rear cylinder Exhaust valve slight leak
Had valve job both heads. Still have same problem.
Any advice would be aperciated.
Thanks 73 sporte
check the push rod adjustment , run a compression test with the bike fully warmed up like after a ride . Nikki
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  #3  
Old 30th July 2012
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Monkeywrencher Monkeywrencher is offline
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Sounds to me all the symptoms of running rich, then eventually fouling a plug.
Over jetted posibly. When I was still running my Bendix, my idle tube was flooding the engine. I couldnt do much with it so I converted to a CV. Look at your tube running verticle from the air cleaner side while its running. See if you see fuel dripping from around the top of this tube.
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  #4  
Old 30th July 2012
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CaptCaveman CaptCaveman is offline
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I'll go with running rich. When you pull the plug is it a nice light tan or a sooty black?
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  #5  
Old 30th July 2012
ultra...good ultra...good is offline
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Quote:
Originally Posted by 73Sporte View Post
after 50 miles or so the rear spark plug won,t fire.
but if i pull the plug wire off about 1/2 inch it will fire.
New Coil ,Plug wires ,spark plug, points and condenser.
Replaced Points and condenser ingiton system witl Mallory E-Spark Ingition system.
Are you using compatible coil, wires, and plugs. Certain type of this, does not work with certain type of that.
Beyond that, and I would verify the ignition first, I had a similar problem and like already mentioned, the carb was way too rich.
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Old 30th July 2012
XLFREAK XLFREAK is offline
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Mixtures that are too lean don't fire good.

50 miles is about one gallon of gas. Do you have an extra filter in the gas line? The tank level drops and not enough pressure to push gas through the extra filter. Take the filter out of the line.

Or, possibly clogged gas tank vent. Next time it happens, just twist the cap open enough to let air in.

You could ruin your electronic ignition pulling that wire off the plug.
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  #7  
Old 1st August 2012
73Sporte 73Sporte is offline
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Thanks for the suggestions I will check the out .And let you know.

Thanks 73sporte
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