bike backfires on take off

1576 Views 10 Replies 5 Participants Last post by charlieb, Jul 24, 2014

irishfan4ya

Discussion Starter · Jul 23, 2014

I have a 2004 Fat Boy with 6800 miles on it that i bought jan of last year in florida. Since then we have moved to alaska. Since moving up here it has developed a back fire issue. It has vance and hines pipes on it. I dont know if po had it re-jetted or not. It backfires during take off and keeps back firing until it warms up, once it warms up it goes away. SO far I have drained the tank and ran seefoam through it. I have taken the carb off and cleaned. I have changed the plugs on it as well. Last weekend I replaced the intake gaskets on it to. What else could I do to make this go away? Any suggestions would be greatly appreciated.

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Dave63

· #2 · Jul 23, 2014

Sounds like the accelerator pump is leaking and needs to be replace. To he honest.....its 10 years old with little mileage. You may want to go through carb and clean it as well, make sure AFR screw is uncapped and all is fresh.

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2stangs8689

· #3 · Jul 23, 2014

Any elevation change??

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irishfan4ya

Discussion Starter · #4 · Jul 23, 2014

Stang not really any to be concerned with. I have asked around bout that to. If there is a big difference could that play a part in it?

Dave thanks for the advice on this. How hard is it to change those and is the AFR screw what is that and where would it be located at? Cleaned the carb out bout a month or so ago. Should I reclean it and let it soak before I put it back together? Would rejetting the carb be a good idea as well? i not sure what was done to the bike before I bought it last year.

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2stangs8689

· #5 · Jul 23, 2014

Dave is the king around here, I figured he would reply, guess I was typing when he was. I would take his advice first, elevation popped into my head, moving from Florida to Alaska.

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Dave63

· #6 · Jul 23, 2014

irishfan4ya said:
Stang not really any to be concerned with. I have asked around bout that to. If there is a big difference could that play a part in it?

Dave thanks for the advice on this. How hard is it to change those and is the AFR screw what is that and where would it be located at? Cleaned the carb out bout a month or so ago. Should I reclean it and let it soak before I put it back together? Would rejetting the carb be a good idea as well? i not sure what was done to the bike before I bought it last year.

Accel diaphragm is the 3,screws on bottom by the linkage cam. Watch for o-rings. Afr scree should be uncapped on a 10,her old bike but who knows. Its behind the float bowl, midway in the back.

Some seafoam in the tank wouldn't hurt.

Jetting on stock cam TC engine: 45 pilot, 190 main and 2,turns out on afr screw. Start there.....

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irishfan4ya

Discussion Starter · #7 · Jul 24, 2014

Dave63 said:
Accel diaphragm is the 3,screws on bottom by the linkage cam. Watch for o-rings. Afr scree should be uncapped on a 10,her old bike but who knows. Its behind the float bowl, midway in the back.

Some seafoam in the tank wouldn't hurt.

Jetting on stock cam TC engine: 45 pilot, 190 main and 2,turns out on afr screw. Start there.....

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Dave what do you mean by uncapped on a 10? Bout the jetting is the 45 piolt and the 190 main is that what i need to put in it? sorry for all the questions just wana make sure i get it right before I start ordering parts for it.Thanks for all the help Dave.

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Dave63

· #8 · Jul 24, 2014

It should be uncapped on a 10 year old bike.

Jetting should be 45/190. If not....change it. You won't know what jets you have until you pull float bowl though.

As well......you'll need to know if jets are HD or Dynojet. HD jets don't fit in a Dynojet emulsion tubes and likewise.

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irishfan4ya

Discussion Starter · #9 · Jul 24, 2014

Thanks Dave ill check it out and see what i can do or find on this.

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Illinios Willie

· #10 · Jul 24, 2014

Hey Irish, go to the carb section and view the sticky on cleaning the CV carb that Dave did, it will give you answers to a lot of what he is talking about.
Its a great reference!!

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charlieb

· #11 · Jul 24, 2014

i have to ask why a rider moves from florida (11-12 month riding season) to alaska (2-4 month riding season) just curios thats all.... think i would be buying skidoos not sure how accurate i am on those riding seasons but there must be a difference between them

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