# Carb problems



## Doc_Brown (Jun 30, 2010)

Hey guys, ok so ive searched and read for two days, and i cant find exactly what im lookin for. Ive got a 07 BF 650sra, im gettin detonation in the air box so i pulled it off and cranked it up my rear carb is backfiring, i thought that it may be the air fuel mix needs to be reset, but for some odd reason i cant seem to find the mixture screw. It only spits and sputters and back fires under very little throttle like the pilot jet may have some trash or something any it, any help would be greatly appreciated, so if some one gets a chane can they send me a pic of exactly where the air fuel mixture screw is located. Thanks fellas.


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## gpinjason (Nov 10, 2009)

there's a little brass "plug" covering the screw... you have to drill a tiny hole in it and pop it out with a pick or something... but if it just recently started and it was running fine before, I would say it's probably trash or something in the jet...


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## drtj (May 3, 2009)

here is a link with the pic of the bottom of the carbs

http://www.mudinmyblood.net/forum/showthread.php?t=4640


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## Doc_Brown (Jun 30, 2010)

thanks for the help guys, im gonna go out here and see if i can get this dang bang firing to quit, the cap was what was throwing me off.


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## Doc_Brown (Jun 30, 2010)

well thanks again for the info. i found the screws and adjusted them, still got the backfire at low rps, guess i got some trash in the pilot jet, i was hopin it was a quick fix but i guess im gonna have to pull them off and tear them down for a good cleaning. Thanks again fellas for the pics.


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## RDs Neighbor (Jun 24, 2009)

Doc_Brown said:


> well thanks again for the info. i found the screws and adjusted them, still got the backfire at low rps, guess i got some trash in the pilot jet, i was hopin it was a quick fix but i guess im gonna have to pull them off and tear them down for a good cleaning. Thanks again fellas for the pics.


Did you recently install an aftermarket cdi? If so that is your problem. Go to the next largest pilot jet or richen the air fuel mixture. I believe 
the timing advance the cdi offers is the problem. If you don't have a cdi. Back to the drawing board.


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## Doc_Brown (Jun 30, 2010)

havent put on a new cdi, i just bought the bf last summer and it has done it since ive had it, but i only put 15 miles on it during hunting season, and since i plan on riding a lot this year im trying to get it running good again. I drained the bowls earlier just to see if there was anything other than gas coming out, and you guessed it there was some trash mixed in with the gas so i guess its carb break down time.

Also do they make a lift bigger than 2" for a sra 650?


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## KMKjr (Jan 9, 2009)

Soak/fill the carbs with carb cleaner (the stuff that foams is better), Sea Foam or something designed to eat the crap in them. Put some Sea Foam in fuel tank. Leave it sit overnight or at least some time and then start. Spray cleaner in carbs and put ur hand over them to suck real hard at you rev engine. If something is stuck in them (like mine were), this shoud get it out, but if not, your gonna have to remove them.

Also check and make sure your plugs are ok, that will also cause a backfire.


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## hondarecoveryman (Feb 28, 2009)

Sounds like the carbs are out of sync . Look on the left side of the carbs between the two you will see a phillips head of a screw ,that is the carb sync set screw . Use a feeler guage to set the butterflies in the carbs to the same . And your problem should go away


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## Doc_Brown (Jun 30, 2010)

well i went and got a can of sea foam deep creep today, sprayed it and let it sit for a couple of hours then fired it up, it def. helped it so i done it again and im gonna let it set all night, hopfully this will clear up the problem cuz i really dont wanna tear the carbs down. Thanks for the help fellas.


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## DaveMK1 (Nov 8, 2009)

Let us know how you made out. Curious to see what you came up with.


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## Doc_Brown (Jun 30, 2010)

Well, i guess ill be taking the carbs off next week, all the seafoam didnt fix the problem, oh well it was worth a shot i guess.


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