Carb swap help **fcr carbs**

i have a 98 yz 400 and i need a new carb i was wondering can i put a carb from a 03 wr 450 that my buddy has?? i need to know asap!!! thanks in advance... i just bought the yz 400 and cant wait to get it goin. let me know if its possible and if i need to modify anything or if all or any fcr carbs will work



anyone know if i can use any fcr carb

The '03 carb is not an FCR, it's an FCR-MX, as are are all the '01 and later models. They will all fit the 400, but you'll find you need to stretch the air boot a bit because the overall length is shorter. The carb also has a cable operated internal hot start, so you'll need that whole set up, along with blocking off the original 400 hot start port at the head.

The YZF carbs work best, and the the '05 and later ones are the best of those. A WR carb will work, but they can be more difficult to tune.

so am i better off not buying this 03 wr450 card off my friend? is it not worth the time and money? and and what do i need to do to block off this port at the head? has any one done this? and any pic would be great so i get an idea on what i need to do i just want this thing to run thats all thanks for the help so far


The WR carb could go on and work perfectly, but (not sure on the '03) most of them have a cap pressed in the float bowl over the pilot screw, and a needle with a single groove in it. Even so, it will almost certainly work better than what you have with a little fiddling.

The hot start on your bike is connected to a tap on the head below the intake port. Get a vacuum cap at an auto parts store for the head, and plug the fitting going to the air boot.

ok thanks guys im gonna get the carb andpretty sure that this thread isnt dead cause im sure ill be back with more questions

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