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Discussion Starter #1
I have a 2006 buell blast (first bike ). Trying to get it started cleaned carb and took off air cleaner etc.. to work on it . With starter fluid can get it started (will not start without it ). And help it running if I'm revving it but it is constantly backfiring from the carb around every 3-5 seconds. Any suggestions on possible causes ? Thanks Justin
 

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You likely have a lean condition. Could be caused by an intake leak, a clogged fuel circuit in the carburetor, float issue, petcock issue, or so forth.
 

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Or, you could have valve issues, allowing combustion pressures back through the carbs. I haven't seen real backfire through the carbs in decades, but it can happen.
 

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Well, firstly get the air cleaner and airbox back on your bike - that's all figured in when the carb is designed. Lack of an air cleaner on some bikes can make them run really poorly just like it is. That itself could be the issue.

After that, like eye said check for intake leaks. Wintersol's suggestion of valve issues also should be looked into also.

It sounds like some sort of lean mixture issue - too much air or not enough fuel..

Nice bike - always been a fan of Buells!
 

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yes....how does it run with the airbox on? Could be something as simple as the air/fuel screw setting. Did u record the setting when cleaning the carbs? Was it running good before?
 

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What's that flickering light, down on the crankshaft? It seems to be timed with the back firing.
NVM - I see it is the timing reference light on the ignition module. I can't help but wonder if that module is firing at the wrong time on occasion.
 

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Discussion Starter #9
Still doing the same thing with the air box on. Recived the bike not running and disassembled (as seen) and not running from a friend for a low price. He has two more salvaged that are not running and is holding on to them if I need any parts (motor/ trans etc..). I can just take them for free.

How would I check for valve issues what would I spay to check for Intake leaks other than the boot
 

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Aerosol carb cleaner would be fine to spray around the intake and carbs.

The flashing light is a timing LED on the ignition. Speaking of, was this ever messed with, and did you verify the timing is set properly? Moreover, if it has a mechanical advance check to see that it's moving freely and returning like it should.
 

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Valve seating problems should show up with a compression test. When searching for what that flashing light was, I found a YouTube video on correctly setting the valve timing; if you have messed with that, it may be worth the time to watch it.
 

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Discussion Starter #13
Ok I have some work to do also notice carb is spitting out fuel (fine mist). When it does that back fire
 

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Ah...led timing cover. That video is dark. I though it was just added on lights (like neon) at first :)
If you find you have bad compression, you might want to do a leakdown test after.
 

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Discussion Starter #16
Ok so cleaned/ inspected every part of the carb. Had to uncover the mixture screw. Got it idiling great. But now when I rev it, it backfires and stays at a really high rpm fo way to long. (Checked throttle not sticking). Also when depress couch make a horrible noise.

When I checked that timing unit it was loose so someone was messing with it. Where would you start ahhh!!!

https://youtu.be/EyS_p692ePs
 

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Timing that is too advanced will cause the rpm to hang, as will air leaks around the carb/intake. Verify the timing first, then get a propane torch and point it around the intake (no flame, of course). Any leaks should show up as a change in rpm.
 

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Had an extremely-similar-sounding "coughing" issue with a Sportster and after chasing lots of potential demons it turned out to be the carb-to-cylinder-head gasket/seals were shot, thus too much air.
 

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Discussion Starter #19
I really wanted to set the timing but the bike will not shift to 3rd or higher tried rocking unable to get it to 5th.
 

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When you pull the clutch lever in that grinding is not good!. You need to pull the clutch cover off and investigate. Idk what that is, but If you're lucky, its just a bearing or a broken disc. Maybe something loose. Hopefully nothing expensive gear related
 
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