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Backfiring in carb

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Old 10-22-2011, 05:21 PM
micg1313 micg1313 is offline
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Default Backfiring in carb

Posting for a friend. He has a 1997 Electrica Glide with only 7200 miles on it . I changed all the fluids & plugs . Front plug was fine white ash in color ,rear plug was jet black .Bike has been sitting for over 8 years .
The two problems I am in countering are the bike is backfiring through the carb as soon as you close the choke . Second is the fuel gage is showing empty when full.
Any help would be great !

THANKS IN ADVANCE .
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Old 10-22-2011, 08:29 PM
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Fuel gauge probably stuffed or wired backwards, carby farts are usually caused by the low speed jet being clogged or the wrong size. If there is anything smaller than a 48 I would go up a size or two but if that don't fix it then the inlet manifold gaskets are probably rotten.
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Old 10-22-2011, 08:31 PM
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The passages in your carb are plugged with old gas gum & altering your fuel air mixture. you can attempt to scrub your system with a full can of sea foam or you pull your carb off & clean it.
You should also pull your intake off & replace the 2 gaskets. You might have a vacuum leak there!
Look for a ground wire off for your fuel guage. Located near your filler cap if you have a dash on the tank.
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Old 10-23-2011, 03:30 PM
micg1313 micg1313 is offline
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Thanks Guys , going to pull carb off and install new jets and gaskets . Really appreciate the replys
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Old 10-23-2011, 05:38 PM
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STOP! You have an intake leak when one cylinder is running lean and one is rich. The two seals on the intake, one to each cylinder is a common air leak point and causes just the situation you explained!

Everyone wants to rip carbs apart as soon as a bike doesn't run right. You can mess up a carb in a blink and have to have a pro reassemble it to get it back together right.

Read here (use the search tools or google your issue). There's a few hundred conversations already in the archives that you can get more details from.
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Old 10-23-2011, 05:47 PM
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I'll give JonnyC a voice and wait. Mine needed a full rebuild. Not vacuum related. Did you compression test?

I have the (dreaded) old butterfly carb!

Last edited by oppirs; 10-23-2011 at 05:57 PM.
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Old 10-23-2011, 05:51 PM
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+1 .... Yep .... Sounds likes an intake leak could be your problem ... check it with a shot of carb cleaner sprayed at / near the connections to the cylinder head and / or boots ... if it increases the idle speed ... BINGO ! you just found your problem ... try and avoid the spray reaching the carb intake as this will give a "false reading". Good luck
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Old 10-23-2011, 06:06 PM
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Just my 2 cents, but it could be a sticking intake valve. That is the only thing I can think of that would cause backfiring through the carb. I would not think an air leak would cause that. I would dump about 4 ounces of Marvel Mystery oil in the gas tank, and run it for a while.
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Old 10-23-2011, 07:10 PM
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Quote:
Originally Posted by Jim Kraft View Post
Just my 2 cents, but it could be a sticking intake valve. That is the only thing I can think of that would cause backfiring through the carb. I would not think an air leak would cause that. I would dump about 4 ounces of Marvel Mystery oil in the gas tank, and run it for a while.
Its totally what an air leak does, it makes the bike run lean and they spit back through the carby when they run lean.
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Old 10-23-2011, 08:28 PM
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Yeah Spanners; That makes sense. That may also be why the rear cyl. is running rich. It might be getting some of the fuel charge that would normally go to the front cyl. Does that sound right?
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