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2000 YZ426F Jetting

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Ok so Im new to the whole jetting so please bear with me.

Im 1,117 ft. above sea level in Phoenix, AZ so it gets pretty hot and dry here.

My bike FMF exhaust is the only mod I can think of that will affect the jetting.

The bike has stock jets all the way around as far as I can tell.

The bike is damn near impossible to start, it also has a little trouble idling as well as back firing when decelerating.

What are my options as far as aftermarket parts/kits to fit these problems?

What jet sizes should I go with all the way around?

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As for jetting, what they came with from the factory was workable, may not have been prime but very workable. The YZ being a "race bike" to start with did not come with a choked up muffler so if the aftermarket muffer had any effect on how it ran from stock it would be a very minor refinment.

So if your have running issues its not likly the jets that are screwed into it but some mechanical issue. Your carb is what I call a "Generation I" of the FCR.

The carbs of that era where built for the gas that was used then, about that time the petrolium companies started adding more alcohol and that rots the rubber used in all the seals. So somewhere in 2001 Kehien started to change into a "viton" brand synthetic rubber that will deal with the modern gas. Then is 2002 they completly redseigned the carb (what I call a "Generation II)

I have a few Viton rubber parts for those Gen I carbs but the cost for them was stagering, frankly you are better off to find a used carb from a yamaha of the 03-05 era

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