Question about Harley Davidson XL 1200 C Sportster Custom Motorcycles

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Xl12002002intakegasketssolveswhatproblem downshifting popping back 12 year old bike has drag pipes but never had popping until now was told intake gaskets.

Posted by Anonymous on


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Hi Anonymous, popping is usually caused by air getting sucked in combustion chamber do bad intake seals leaking. Leaking exhaust gaskets can also be suspect. Remove air cleaner and backing plate, while engine is idling spray WD-40 or Brake Kleen around intake manifold to head area, if RPM's increase you have an intake leak and seals need to be replaced, also spark plugs will be burning whiter than normal. Good luck

Btw, I’m available to help over the phone in case u need at

Posted on May 12, 2015


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Posted on Jan 02, 2017



  • 2336 Answers

SOURCE: Engine skipping & popping

sounds like a lean out condition... pull plugs and look at them if there white and sooty its to lean.... jet it up or replace baffles..i think your on the right track with backpressure theory!

Posted on Nov 20, 2008



  • 3 Answers

SOURCE: Honda NTV 650 Deauville Head Gasket

Leaking from the black o/flow pipe in traffic,.....check your fan switch/radiator fins(clogged?) hope this helps....dave

Posted on Apr 23, 2009


  • 1 Answer

SOURCE: i put drag pipes on,now crank position sensor

Check out the:
They have answers regarding the Crank position sensors. THey do fail. the symptoms are poor off idle performance and sputtering. Valves have nothing to do wih it.

Posted on Mar 16, 2010



  • 4565 Answers

SOURCE: when i let off the gas to slow down a little then

It sounds like the typical "lean from the factory" problems but let's check one other thing first. Take ht air filter off the bike leaving only the backing plate on it. With the engine OFF, crank the throttle wide open. When you do this, you should see a shot of fuel squirt from the brass nozzle in the mouth of the carb. This is the accelerator pump. If you don't see a shot of fuel squirt into the carb, the pump diaphragm is bad or there's trash plugging the hole that lets the fuel get to the pump.

If you do see the shot of fuel, you may simply have a carb set too lean. I'd go with a #48 or #50 slow jet in the carb. Maybe add a 0.020 inch thick washer under the needle to raise it up just that little bit enrichening the mid-range.

Good Luck

Posted on May 13, 2011



  • 4565 Answers

SOURCE: bike runs but back fires

You didn't say what year or model bike it is but I would guess, and that's all this is, that the rear cylinder is running lean for some reason. You may have an intake vacuum leak sucking air into the rear cylinder. That's my best guess.

Good Luck

Posted on Jun 02, 2011

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Leaking from the black o/flow pipe in traffic,.....check your fan switch/radiator fins(clogged?) hope this helps....dave

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