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Discussion Starter #1
Out of curiousity I was wondering if I could get 2 of the YFZ 450R carbs and manage to put them on my YFM Raptor. I ask this because the are 39mm FCR Carbs and they would essentially be the same thing as getting aftermarket FCR carbs for the YFM; am I correct? Correct me if I am wrong. I am here to learn. Has it been done if it is possible?
 

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the problem is both carbs would have accelerator pumps so you would fight jetting it correctly, would have to build a custom intake to fit them and have a bionic thumb to operate them.
 

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So in reality it isn't worth it? I assume that it would be possible but what you are saying is that it is just best to pick up carbs. Right?
 

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yeah, just buy a set of 39s to fit it. If money is the issue you can split a set of streetbike carbs to work, use the right two carbs, its a PITA to do it but you can save some money. Most street bike FCR carbs are downdraft carbs though, in short, that means they will only work on flat ground in a rappy, you can not go up hill with them for any distance because the floats don't open on an incline.
 

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Why would having 2 accelerator pumps be a problem? I dont know much if anything about the YFZ carbs but isn't there some type of adjustment so that the dont "pump" as much fuel?
 

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I figured that if I got 2 of the carbs for dirt cheap I would try but if coalshedracing says it isn't worth it then I trust their input.
 

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I had the mikuni tm45 on my old ds650.It had an accelerator pump in it.this carb had a real small rod that ran off the throttle to activate the accelerator pump.I just rotated the throttle and slipped the rod out and re jetted accordingly this deactivated the pump.Is this the way the yfz carbs work? If so its a pretty easy fix to eliminate the pump.
 

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1fst690 said:
Why would having 2 accelerator pumps be a problem? I dont know much if anything about the YFZ carbs but isn't there some type of adjustment so that the dont "pump" as much fuel?
Its a problem because the carbs won't fit side by side inside the frame and still go into a standard intake manifold. You might be able to make a manifold and fit them but even so I would have serios doubts as to whether or not two of these carbs would even fit in the frame considering they both would have throttle plates and accelerator pumps.
 

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That is what I did was buy two separate 39 fcrs and make it work, csr you are right though it was a pita to make it all work, I had to machine the acelarator pump off one float bowl and weld it to plug the holes, I only run one carb to about 1/2 throttle first though before the second one opens when trail driving. In atv pulls I run the second one first to launch and then open the first one with the accelerator pump to make her haul ass.
 

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CoalShedRacing said:
1fst690 said:
Why would having 2 accelerator pumps be a problem? I dont know much if anything about the YFZ carbs but isn't there some type of adjustment so that the dont "pump" as much fuel?
Its a problem because the carbs won't fit side by side inside the frame and still go into a standard intake manifold. You might be able to make a manifold and fit them but even so I would have serios doubts as to whether or not two of these carbs would even fit in the frame considering they both would have throttle plates and accelerator pumps.
and also all the electrical things the carbs have
 

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CoalShedRacing said:
1fst690 said:
Why would having 2 accelerator pumps be a problem? I dont know much if anything about the YFZ carbs but isn't there some type of adjustment so that the dont "pump" as much fuel?
Its a problem because the carbs won't fit side by side inside the frame and still go into a standard intake manifold. You might be able to make a manifold and fit them but even so I would have serios doubts as to whether or not two of these carbs would even fit in the frame considering they both would have throttle plates and accelerator pumps.
Thanks! I'm having the same problems with my Lectrons right now.
 
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