# 05 BF750 Carb problem



## extreme750 (Jun 22, 2009)

I have an 05 BF750 and when I remove the air box lid it won't take any throttle just choke out when i hit the gas, but with the lid on it will take throttle and rev all the way out but I'm getting a popping sound at idle and part way to mid range. any ideas what it could be, and is there a air/fuel mixture screw? How could i access the screw?


----------



## ApexerER (Jul 7, 2009)

My chokes were stuck open and it did the same thing. I would take the carbs off and remove the chokes, clean up the plungers and lube them. I had mud behind the o-ring somehow. The airfuel screw is right there when you remove the carbs. I believe you turn it all the way in and then back it out 2 1/4 turns but i would have to look it up to be certain.


----------



## phreebsd (Dec 16, 2004)

i thought you had to drill out the little covers over the A/F screws?


----------



## FABMAN (Dec 18, 2008)

I have pics of how to find and drill the covers to assess the A/F screws. if you'd like


----------



## drtyTshrt (May 27, 2009)

FABMAN said:


> I have pics of how to find and drill the covers to assess the A/F screws. if you'd like


 how about pm them pics to me please or just post them. I think that I saw mine exposed when I had my carbs off.


----------



## RDWD (May 11, 2009)

I had a somewhat similar problem. I didn't mess with the air box lid but it was popping at idle and through mid range. I contemplated rejeting but I decided to try a little peice of duct tape covering about half of my air intake on the snorkle. It runs better than ever now I guess I was getting to much air. I didn't even know one could have to much air but a little peice of duct tape did the trick and was a lot easier than rejeting. Good luck.


----------



## wood butcher (May 11, 2009)

u can get reducing bushings at lowes or homedepot to put into the end of snorkle . try different sizes to find the best one


----------



## FABMAN (Dec 18, 2008)

hear are a few


----------



## SWAMPMAFIA (Apr 9, 2009)

I see where he said you turn the A/F screws all the way in then out for adjustment? Is that correct, thought you turned them out then in for this purpose.


----------



## SWAMPMAFIA (Apr 9, 2009)

sorry guys nevermind, just had a small brain fart, later


----------



## RDWD (May 11, 2009)

wood butcher said:


> u can get reducing bushings at lowes or homedepot to put into the end of snorkle . try different sizes to find the best one


Thanks I will try this and let yall know how it goes.


----------



## drtyTshrt (May 27, 2009)

Thanks for the pics Fabman My screws are already exposed so no need for me to drill. I did not mess with them while I had the carbs off but I might should have. remember I was tell about putting the extra UNI filter under my K&N. It popped at low end before I did that,but with the UNI under the K&N in it just GOES. But this morning I took it back out to test it after I did the choke to see what it does. If it still pops I might just try the Air fuel mixture screws. I said I was not going to take it back apart but it seems like there will always be something.


----------



## extreme750 (Jun 22, 2009)

there no way of adjusting the air/fuel screw with out removeing the carbs?


----------



## drtyTshrt (May 27, 2009)

I thought about that yesterday after posting and when I raced karts we had what was called a remote A/F cable. It is just like the idle cable that is on the bike now the one right above the pull start. Anyhow I am thinking about getting two of those and tack welding them to the screws under the carbs and mounting them on the handel bars or something like that. just a thought I had.


----------



## Muddy Brute Force (Dec 17, 2008)

Try adjusting the air/fuel mixture screws 2 to 2 1/2 turns out. If that doesn't help, then try shimming the needle's 0.40 thousands (2 #4 brass washers on each needle). If that is no help, you may have to change the pilot jet to the #40 pilot jet. Hope this helps.


----------



## SWAMPMAFIA (Apr 9, 2009)

I got so frustrated taking the carbs on and off i took two bits from a tool kit and jb welded them to the A/F screws. Now you can reach in through the right side and adjust them alot easier.


----------



## IBBruin (Feb 10, 2009)

SWAMPMAFIA said:


> I got so frustrated taking the carbs on and off i took two bits from a tool kit and jb welded them to the A/F screws. Now you can reach in through the right side and adjust them alot easier.


Any chance you took pictures of that?


----------



## FABMAN (Dec 18, 2008)

all i do is take a 1/4" 1/4 drive socket and tape a standard bit to it and go at it with that. however i do remember stogi had found something like drtyt is saying but no welding. hear it is at https://www.ktm-parts.com/mm5/merch...ore_Code=K&Product_Code=59-1002&Category_Code=









if you type (*R&D Flex Jet Remote Fuel Screw)* in on e-bay you can find it for $29


----------



## drtyTshrt (May 27, 2009)

Thats the one. Actualy that one is for our specific application R&D is a great company I but allot of stuff from them for my sons dirt bike.


----------

