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Discussion Starter #1
Hey guys!

first time poster/owner.

i just bought an 09 custom, and have a little over 350 miles on the clock so far. well, i noticed that when rev matching to downshift, every so often i get what seems to be a backfire into the intake. its a pretty noticable pop that i can hear, and feel on my right knee. i dont think it should be normal. think being the keyword.

care to share some knowledge with me and let me know if this is normal, or what the problem may be if there is one?

thanks in advance
 

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Hmmm, backfire into the intake. Don't think I've heard about that before. What do you mean by "rev matching to downshift"? What was your speed and what gear were you going to?
 

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Discussion Starter #3
just bumping the throttle to downshift. and im downshifting into fourth between 30-40, 3rd betwen 20-30, 2nd between 10-20 or so.
 

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Does this ever happen when you use the clutch to shift? I've always been afraid to shift in that manner. I paid a lot of money for it and I ride it pretty much by the book ... well I might speed a little here and there. :) Maybe that doesn't hurt the bikes at all, I don't know. But I'm far too cautious to do that. Is there a reason that you choose to not use the clutch?
 

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Discussion Starter #5
oh no no no..lol. i use the clutch. think of it like this.

clutch in, kick down a gear, bring rpms up, let clutch out. but u just kinda flick ur wrist. it saves the whole tire chirp thing if u let the clutch back out to fast. lol
 

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Ah, I see. Okay, now I don't think it's anything to worry about. You are shifting in the right range. I'd say it's just related to your break-in period. While I was breaking mine in there were several new noises, pops, crackles, and clicks that make me a little worried. But as I put more and more miles on it they went away (or I just got used to it). I've got 6,500 miles on it now and she's the smoothest bike I've ever ridden.

I've been on the forum for quite a while and I don't recall ever seeing any issues like this. You might give the forum Search tool a try just to be sure, but this is a new one on me. So long as the bike isn't handling funny, I'd give it a little more time and see if this continues.
 

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Haven't noticed mine doing that but I know Harleys often queef through the carbs. I know 4 stroke MX bikes also tend to backfire through the intake and have backfire screens to prevent the air cleaner from catching fire. Don't think its anything to worry about as long as she is still running alright.
 

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Mine does the same thing sometimes. Usually I only notice it if it's a little chilly out and it's not warmed up yet. It happens to me during rev match too. I don't think it's anything to worry about.
 

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Do a search on "marbling"
 

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I don't think it's the intake unless there's a timing problem...which is not likely. The bike runs rich and when you blip the throttle you're dumping a lot of fuel in the cylnder that won't get burned. Check exhaust pipe bolts too. They tend to vibrate loose and let fresh air in the fuel rich exhaust system resulting in backfire.
 
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