08 Blast backfiring under acceleration

[jet pilot]

I tried the new TPS. Still cant get the voltage to .5. The idle screw is backed out all the way and there are no obstructions stopping the throttle plate from closing. I can only twist the TPS to .947v.

Tried a NEW ignition module---no Different.

I brought the bike to the HD Dealer who is well versed in the Blast as they still use them as trainers. Time (and $$) will tell, I hope. Keep the ideas coming though if you figure this out..

[two_fry]

Just out of curiosity (and in part because i had similar issues, and was going to try a few of the things from this thread before i figured it out)

when you take the carb apart, and you take the larger jet out, theres that little silver tube that sits on top of the jet, and into the throat of the carb. if that one little peice is in upside down, it will cause issues pretty close to what you are having. when it is in the right way, it sticks out into the throat of the carb more than the other way.

[jetlee]

1 - 48 pilot is too rich for your modifications and elevation, put in a 45.

2 - Put the stock needle back in, shim it. Your mods don't require an N65 and coupled with your rich pilot could flood your chamber. An N65 has a different taper, it's not the same as shimming the stock needle.

3 - This sounds like a classic case of upside-down needle-jet (the silver thingy).

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This is why we tell everyone to NEVER "clean" the carb. You don't need to, especially if the bike runs. I don't care if it sat for a year, try running it first.

EVERYONE always screws up when "cleaning" their carb.

All that a "cleaning" should entail is:
1. Remove fuel bowl
2. Spray carb cleaner through all orifices until it flows nice and clean
3. Put fuel bowl back on.

THAT'S IT!

http://buellridersonline.com/forum/s...ead.php?t=8291