After i go on long straightaways on WOT, it starts poping and backfiring. it takes a few seconds to go back to normal after i get off WOT still poping. seems to me that theres not enough gas in the carbs. the float level is good. i got 167.5 and 172.5 main jets an 25 pilots. 2-1/4 turns out on both carbs, i am running GYTR needles. like in the instruction manual for the exhaust Fatboy 4.

 

The popping is from a lean condition on the pilot circuit. Whats happening is your going from wide open where your engine is pulling strong, but then when you let off the pilot circuit takes over and it can't keep up with the high RPM's so it leans out. Even tho you have let off the gas the RPM's are still up and until they come back to normal it's going to pop, which is why you experience this happening.

Try turning in the air screws a bit and if that dosn't seem to help you might need to step up the pilot one size.

 

I just read my post and i notice i didnt explained that it kept just making the poping while on WOT. this only happens when im on WOT for a min or more( from 1/2 a mile or more ). If i dont have teh THrottle Wide OPen and i have it 3/4 of the way it works fine, but then my buddy passes me.

 

too lean on the main then, go up a size on the main and see what happens

 

it seems to be that the carb runs out of gas because it runs good on full throttle just not after a while. and its after like 1/2 a mile. it was hapening at the end of a straight away at a track and thats the only place i was having a problem.

im going to have to change my jets again.

anyone else has run into this problem??

 

anyone else have any suggestions?

 

You say the floats are set right? Are you using a in-line fuel filter, someitmes they restrict flow if your using one thats too small and the carb can't keep up.

 

sounds like your floats need to be checked and possibly adjusted

be sure your needle valve/float connection is operating smoothly,,,,and that the needle is opening fully and that it is unobstructed


you are running the bowl dry,,,,,fuel isnt getting in there fast enough

just gotta figure out why

 

do a clear tube check on your float level,,,,,,,,(sixsixt method)(searchable)

at that point you will also be able to recognize any slow flow coming from one or both carbs,,,,,if you watch them drain for a bit

you could even measure what the flow rate is on each carb if you want to get creative with a measuring cup and wristwatch

Raptor carbs can be a royal pain if they are off

 

right now i have the levels at the mating surface. its supposed to be lil less but i left tit there trying to compensate fo rthe biger jets.

Now, I do have an in-line filter. could that really be the problem??

i was thinking of buying some fcrs or the edelbrock to stop messing wth the carbs. its such a pain to keep messing with the damn carbs.

and i had the feeling that it was something like teh carbs not having enought gas because the damn plug is nice and tan/ brown color not white or black.