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pnut420
08-13-2003, 04:47 PM
my brother bought a 400 ex and the guy put some sort of aftermarker carb on it. It is i Mikuni and I think its off a XR400, seemed better than a stock EX carb, but I cant believe how much difference the FCR made. Right now Im running a 165/52 and it seems to be running a little bit rich. I think the jetting is good, so should I just bump up the needle up a couple notches? It rips on the mid to top but bogs a little on the lower RPM.
K_Fulk
08-13-2003, 04:52 PM
Try dropping the needle down that should help you. I have the needle on mine all the way down (top clip) but it might be a diffrent needle than you have.
pnut420
08-13-2003, 05:17 PM
Ill give that I try tomarrow thanks
JD400exrider
08-13-2003, 06:39 PM
pnut,

Try adjusting the fuel screw. We are about the same elevation. I am in sacramento. I bought mine from C&D and colby jetted it 165 and 52. It seemed to run nice, however i bumped the main up to a 168. Thought i may be running a little lean.

Mine bogged a little on the low end. (with the 165) Turned the fuel screw out 1/4 - 1/2 turn. That did the trick. She rips. :D I am going to take in to the dyno this weekend and have it hooked up to the sensor to see how the jetting is. The dyno has a sniffer that goes in the pipe to read the air / fuel.

Norcalatver lives around the corner and he is running his 493 with the fcr 39 at a 160 main jet. Was running a 170 something before it was checked on the sniffer. Dropped down to a 160 main.
pnut420
08-14-2003, 10:43 AM
It smells like their is unburnt gas coming from the exhaust, so I will mess with the fuell screw and move the clip which way? I dont even know what the clip looks like I know its on the top of the carb thats it
K_Fulk
08-14-2003, 04:43 PM
I had an oc-emr needle all the way down(top clip), Today i got the oc-emr needle from c&d racing (the one that sparks recomends). And i have that 3rd clip from the top.

Check and see what needle you have in yours.
pnut420
08-15-2003, 11:49 AM
Originally posted by K_Fulk
I had an oc-emr needle all the way down(top clip), Today i got the oc-emr needle from c&d racing (the one that sparks recomends). And i have that 3rd clip from the top.

Check and see what needle you have in yours.

I pulled the puld and it was fouled from the other plug, then I changed the jets and it is pretty close to dialed in, this carb was easy to work with
K_Fulk
08-18-2003, 02:45 AM
The needle and fuel csrew pretty much cured my problems raced friday night and pulled a hole shot in the 2nd race and started 2nd in the 1st race.