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Buell Forum » Knowledge Vault (tech, parts, apparel, & accessories topics) » Troubleshooting (Poor Starting/Running/Handling/Ride Issues) » Archive through August 17, 2013 » 03 Blast Power Loss / Backfire « Previous Next »

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Maddoc
Posted on Wednesday, February 20, 2013 - 06:02 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hey guys, I've been following these threads for the past two years when I got my blast but only just now got an account made, so I'd like to give an official hello and thankyou to all of your contributions that have helped me thus far.

So I have a 2003 buell blast that has somewhere between 11-12k miles on it. In the last six months I've put new top end gaskets on it for everything above the cylinder, replaced das boot, new spark plug, new stator, new intake gasket, new clutch cable, and a new battery.

Two weeks ago I was having an issue where the bike wouldn't idle - it only wanted to run at higher RPM so I had to rev the engine to keep it alive if I was at a stop. Thinking it was an intake leak (I could spray some brake cleaner at the intake manifold and the RPM would fly up) I replaced the intake gasket, as mentioned above.

After getting this done, however, the problem flip flopped. The bike now idles GREAT but if it's cold it won't take any throttle at all, it just chokes out. Thinking I may have knocked some dirt loose in the carb I took it apart and ran cleaner through both jets and all the ports (a move I'm sure most of you would not recommend to do first), but the carb was shinier than baby's bald head inside. I also checked the petcock on the fuel tank and gas pours out just fine - the fuel line to the carb is perfectly fine as well.

After I put the bike back together I was able to at least ride it around, but I would have really bad random spots where I would just lose power when I throttled up, and I either had to hold the throttle full open and wait for the engine RPM to spike up, or pull the clutch in and let it idle for a minute before I could put a load back on the engine. It also back fires fairly often (which it was doing before I changed the intake gasket).

I've seen a few posts similar to this where you guys recommended changing the ignition module but I wanted to make a post for myself so I could get direct opinions.

Just for some background information, I'm 22 and have a fairly good mechanical background - I can take pretty much anything apart and put it back together if I know what I'm trying to fix, but this problem's been stumping me for a few days now. Oh! I also noticed some fuel being pushed back into the airbox from the carb. I'm not sure if that's a result of the backfiring pushing fuel backwards through the carb or if the carb is flooding and I have too much gas in my combustion chamber.

Sorry for the SUPER long post, but any ideas are more than welcome!
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Sparky
Posted on Thursday, February 21, 2013 - 01:07 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I would check the condition of the carb diaphragm and make sure the slide moves up and down freely. Also check that the air filter is clean and not blocked if you haven't done so already.

One more thing to check is that the fuel tank vent valve is not plugged and its hose is not kinked. If either of these conditions exist then fuel starvation at higher speeds can happen resulting in a sudden loss of power. A quick check for this though can be made by opening the gas tank filler cap slightly at speed and noting if there is a quick air sucking sound followed by a resumption of power.
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Maddoc
Posted on Friday, February 22, 2013 - 12:04 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

So I'm starting to think my problem isn't that the cylinder isn't getting enough fuel, but that it's getting too much. When the bike is cold and I start it I either have to let it idle or crank it full throttle - anywhere in between causes it to die. When it's sitting there warming up (as well as when I pull up in my driveway) I can see clouds of white smoke drifting up in front of my headlight - I assume it's gas vaporizing in the exhaust manifold. I can also see an occasional burst of white smoke shoot out of my tail pipe if I let it idle then crank the throttle open

Everything in the carb looks fine - the diaphragm seems to be in good shape and the needle appears to be able to slide freely

Thoughts?
(oh also, are the auto enricher and the automatic choke the same device on the blasts?)
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Andersonhdj
Posted on Sunday, February 24, 2013 - 09:41 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

If it's running as rich as you think then your sparkplug should be fouling fairly regularly if not within a few hours.
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Sparky
Posted on Sunday, February 24, 2013 - 02:55 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

If it's too rich, there will be black smoke out the exhaust not white smoke and the need to open the throttle more to give the engine more air otherwise it'll die.

You might try replacing the fuel in the gas tank. The gas in there might be contaminated with water which could explain the white "smoke" you're seeing in which case it's likely "steam". Also since water doesn't burn, it can cause misfiring and the need to crank the throttle to keep it running.
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