Fcr 39 Help!

[torqen2k1]

I installed a YFZ450 carb on my 426ex and having some problems. I had a 52 pilot before and just woulnt want to idle so i just put a 62pilot now and it idles now but just back fires out the exhaust and the intake while its just ideling. So the deal is that if i take it for a rip down the block and let off the throttle it idles very high like the throttle cable is stuck but soon as stop i have to have it in gear and hold the brakes and let the clutch out and then it will go down and idle normaly.

[drew416ex]

In my 440 stroker I have a 50 pilot, 205 main and needle in the middle

[NacsMXer]

Sounds like you have too much pilot there. 52 to 62 is a big jump.

In my 452 stroker with a FCR 39 I run a 52 pilot and it idles great. I had some trouble with the idle cutting out sporadically, so I turned in the pilot screw a little to lean it out. That cured my idle right up, it had a much faster healthier idle.

Did you try adjusting the pilot screw on yours yet?

[torqen2k1]

yes i tried the pilot screw but it didnt help but make it just die out, but i dont understand the fact the once i rev it up it just stays up there ideling realy fast for about 10seconds

[torqen2k1]

Oo by the way just riddin around last night and it was chilly night i noticed the header starting to glow red

[drew416ex]

That would mean you are lean, but those jet sizes are huge for a 426. maybe you have a air leak somewhere.

[katch26]

Originally posted by drew416ex
That would mean you are lean, but those jet sizes are huge for a 426. maybe you have a air leak somewhere.

thats what I was thinking....shouldnt it run at least comparable to the jetting of the bike it came off of?

[torqen2k1]

Can someone tell me what size leak jet you have in your FCR carb? I have a 50 leak jet as of now.