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450R carb on a 450X settings

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I'm building a new motor for my 450x and I picked up a 450R carb cheap. Any suggestions on how to set it up for a 450x with a 478 big bore kit. All the typical mods will be done.

I had a good idea of where to start with the X carb but I'm not sure what a larger carb would do.

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Start with the same jetting you ran in the X carb. You may have to run a size larger main jet, may be not. Really depends on how perfect it was before. You need to first properly set up the fuel screw for a perfect hot (after being ridden for at leas 15 minutesd, not just idling in the garage) idle. Then do tests on the needle,using various throttle openings all under load. Then the main jet. Then you finish up testing and setting up the AP.

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I'm building a new motor for my 450x and I picked up a 450R carb cheap. Any suggestions on how to set it up for a 450x with a 478 big bore kit. All the typical mods will be done.

I had a good idea of where to start with the X carb but I'm not sure what a larger carb would do.

You didn't say which year R carb.

The R jetting should be just fine, IF you have fully uncorked the X motor, with a R cam, and free-flowing exhaust.

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