need help with backfiring

[dave07ex]

My 08 Ex (mods in sig) is backfiring when the throttle is opened at all and will only idle for a minute or so before it dies. When idling, if the throttle is opened even just a tiny bit, the engine dies. I have done a total cleaning of the carb since the gas in the tank was old. By a total cleaning i mean jets and a/f screw removed and cleared using carb cleaner. New 93 octane (same as always) is now in tank, after a good flushing. I started at 2 turns out on a/f screw, went as far as 3 turns and it still backfires when the throttle is opened. Any suggestions on what to do next?

[Stickman400]

What position is your needle in? I had a similar problem when my needle was in the bottom notch. Put it in the 3rd notch down from the top and see what that does.

[dave07ex]

Its at the 3rd notch from the top. At this point im fairly certain that its not a carb issue. Fuel pumps out just fine when the throttle is opened. Pilot jet and pilot circuit adjustment are clean. Main and needle were removed and cleaned as well as all related holes and orafices. I'm getting really bummed now.

[Pipeless416]

Originally posted by dave07ex
Its at the 3rd notch from the top. At this point im fairly certain that its not a carb issue. Fuel pumps out just fine when the throttle is opened. Pilot jet and pilot circuit adjustment are clean. Main and needle were removed and cleaned as well as all related holes and orafices. I'm getting really bummed now.

got any air leaks around the intake boot?

[CJM]

Change the plug, see what happens.

Take carb apart, clean all jets, orifices and make sure the the float and float needled are clean and good.

[dave07ex]

None that i can find. Double checked clamps and hose connections. It has trouble firing up, which it never had before. When it does fire up, i have the backfiring when i crack the throttle, if it stays idling for long enough.

[dave07ex]

Originally posted by CJM
Change the plug, see what happens.

Take carb apart, clean all jets, orifices and make sure the the float and float needled are clean and good.
Disassembled and cleaned the carb twice, i sure its clean. I can pull the plug but cant change it cuz i dont have a replacement.

[Pipeless416]

i would just get right to it and start checking valve lashes.

[DragonGunner]

Hard starting an backfiring = lean condition.

If carb is all clean an you have turned air mixture screw out 3 turns, try another turn out an keep going until it backfiring disappears...also you can go up on the pilot jet a size or two, then start back at about 2 turns out on the air mixture screw an work your way out until it starts easy an doesn't backfire.

[dave07ex]

Originally posted by DragonGunner
Hard starting an backfiring = lean condition.

If carb is all clean an you have turned air mixture screw out 3 turns, try another turn out an keep going until it backfiring disappears...also you can go up on the pilot jet a size or two, then start back at about 2 turns out on the air mixture screw an work your way out until it starts easy an doesn't backfire.

Im using a 42 pilot and it ran very well last year without any changes other than sitting for a while with gas that was getting old. Before flushing the tank i did try to start it but no dice, figured it was just bas gas (damn you ethanol).

[JOHNDOE83]

sometimes when old gas is in the carb, no matter how many times you clean it, it just wont work right.

I suggest using a air compressor with a spray nozzle, take all jets out and take the float out along with the ceet. Soak the carb or use lots of carb cleaner then spray out every hole in the carb with air making sure that the air is coming out other holes in the carb.

Then take a tooth brush to the pilot jet and spray out all the jets with the air hose.

If that dont work you may need new pilot jets.

Backfiring is deffinetly a lean condition, along with poor starting which leads me to believe the pilot circuit is still clogged.

[dave07ex]

Well i suppose that i'll have to do another tear-down and use a couple cans of carb cleaner soaking the parts. I'll update the thread later in the week with my results. Thanks to everyone who replied so quickly.