250x/300ex fcr carb, anybody using one??

[wishmasstir]

picked up a 37mm fcr carb to use on a 350x motor in a 250x frame, basically it will fit in the manifold okay but will need a spacer for the rear tube but thats not the problem at all. the petcock from the tank is hitting the choke lever on the carb. we cant sit the tank down all the way because of this. i was planning on actually on cutting out the fitting on the gas tank and welding it on an inch or so forward on the tank so that the choke would clear. i was just wondering if anyone else ran into this problem or has done some modifications to make one of these carbs work on a 250x/300ex/350x motor.

[bwamos]

Perhaps you could make an aluminum spacer plate (dont forget to use a 2nd o-ring for the seal, may need to dremel a groove in the spacer) between the insulator boot and the engine to move the carb back about a half inch. Might fix your intake boot problem at the same time. ;)

[wishmasstir]

yea...i was already thinking about that but just wanted to see what everybody else has done

[dork]

i'd use a fcr39 400ex kit. its the right length and doesn't have a choke to get in the way. i have one of those 37s off a yz250f and its longer and shorter than the 400ex 39. just use a 300ex manifold and a 350x or 400ex airboot. mine fits fine and nothing hits. i clearanced under the tank a little over the slide cover to be safe though.
http://i8.photobucket.com/albums/a18/strato-streak/000_0234.jpg

[wishmasstir]

are you saying that your 37mm fit fine using the 300ex manifold and 350x/400ex intake tube??? or just the 39mm 400ex fcr kit

[dork]

no, i'm saying use the fcr39 for the 400ex. it saves alot of headaches. i think 2muchquad on here used a 39 off a yz and he had to make an extension, not sure about the choke though. your motor will handle that 39 fine. also use the 300ex manifold instead of the 350x. the 300 has a larger spigot that fits the fcr and 400ex carb better. also i ran the 400ex airboot in the stock 300 box. it flows the best but you need to make a small extension bracket since its shorter. and if you're running a thumb throttle, a stock yfz450 cable fits nice in the honda housing.