The unsolveable, on going problem

[speedy400]

Well I dont really know what to base my problem on, if you've seen my previous threads("fcr problems" and "stock CDI failer")the problem has beaten me to a pulp. If you dont want to go back and read what the problem is here it is basically, one day it just started doing this-1/8th to about 1/3rd throttle, it coughs, pops, and just plain old runs like crap, I tried changing out the cdi with a friend of mine's, no success, tried every jetting combo that I can reasonably think of, tried dissassempling the fcr fully and sprayed it down real good with carb cleaner, also new spark plug, no luck...my motor is equiped with-
Uni filter, no lid
39mm FCR
port and polish
416 JE piston
10.8 to 1 comp.
hotcam stg 2
powerbomb header
HMF slip on


I am clean out of ideas.help!-darren

[400exdad]

Darren, I am not familiar with FCR's but what I can say is that if you haven't shot air through every orfice in that carb, a grain of sand could still be in there. If you have done the air pressure treatment, I would try putting the stock carb back on (if you have it) and see what happens. You wouldn't neccasarily have to hook the cable and all back up... I would also thoroughly inspect the carb boot in front of the carb and where it bolts to the head. I mistakenly left the front clamp loose on the 300 and it drove me crazy for almost a year. Duh... :) Good Luck!

[speedy400]

well, thank you very much for saying that, I totally forgot about checking that boot after the carb! I'll have to rip it apart tmorrow and make sure everything is ok, I remember having problems with that boot with that little o ring falling out of place because I ported it to match my intake porting. thanks!!-darren

[cals400ex]

yes, check all boots for leaks. some people just have a worn out o-ring in that boot. also, i would consider take the top of the carb off and removing the needle. see what clip position the needle is on. also, spray down this portion of the carb good. the clip position may just need to be changed.

[Chef]

Make sure that intake boot on the engine side of the carb isnt broke. Mine did that and it felt like an ignition problem but when we took the carb off the boot came with it.

[nakomis0]

I had something like this when I first bought my FCR. We tried everything. Then finally decieded the carb was just plain bad, and I exchanged my new FCR for another new FCR and the problem went away.

Don't know what the problem was neither did my mechanic... Sooo my post probably doesn't help you at all.. hrmm.. sorry .. good luck.

[speedy400]

Alright todays testing failed, there are no leaks, proven by spraying the boots down with carb cleaner, my father said the rpms would go up if I had a leak, well no leaks, then I put it in neutral and reved it up to the rpms that it stumbled the most, and took off the air filter, no dirrence, then I almost completely covored the boot opening with my hand still at the same rpm, still made no diffrence, so if its not carb problems(as I know of), its not air leak problems, its not the CDI, whats left? timing off, maybe flywheel key got sheared just a few degrees? is it prossible the coil is wanting to go out? would a valve out of adjustment do this?thanks-darren

[velocityatv]

My buddy has close to the same set-up and was running in to the same problems. PM him, his name is Tim ( terko440 ) he was having the same problem, I think he changed the acc pump and something else, but I can't remember, and it was fixed. But I would deffinitly check the valve lash and timing, could have possibly slipped. I would deffinitly PM him he could help you out. He's gotten pretty good at those fcrs. Hope I helped :D

YOu would think a carb that cost a gazillion dollers would not need so much tuning to work...:confused:

I"ve debated for months on getting a HRC cam or FCR carb and the cam sounds like sure winner compared to this FCR dialing in crap...:huh

[Chef]

Rico just so ya know, I have had 3 of them that worked perfect from the time I put em on to the time I take em off with very minimal tuning. The only problem I've had is that the CRF takes so much fuel that a 55 pilot was too lean and actually burned all the coating off the header...threw a 62 at it and its great. I have a 39 I could sell you for $350 and I will jet it...tell me what you have in your stock carb and I will do my best to get it close...

[Honda250XRacer]

hey i had a simular problem ...my pipe core was broken inside and made it run like **** at about those throttle positions ..take a look or listen for something loose maybe i dunno....

..Trent...

[speedy400]

Checked the pipe, thats all good, uhhhhhhhhhh, I guess I could check the valves tonight.... Cmon guys I need some more suggestions, I'm missing out on the prime time to ride in the year!!:( :( thanks very much for the help so far though.-darren

[dork]

make sure when you clean the carb to take off the intake bell thats on the air box side and take out your pilot air screw(or jet) and main air jet. they're recessed pretty far and can be hard to clean.

[speedy400]

HEY HEY!!! I think I figured it out!!! like on a previous post said something about accel pump going out, I took off the carb(filled the bowl with gas) and pumped it a buncha times, nothing happends, no gas shoots out. BTW do you guys know if gas is suppose to go in the diaphram pump area? or is that just for air? because I took the bottom of the pump off with the bowl on and filled with gas and it was empty with no gas coming out?thanks-darren

Originally posted by Chef
Rico just so ya know, I have had 3 of them that worked perfect from the time I put em on to the time I take em off with very minimal tuning. The only problem I've had is that the CRF takes so much fuel that a 55 pilot was too lean and actually burned all the coating off the header...threw a 62 at it and its great. I have a 39 I could sell you for $350 and I will jet it...tell me what you have in your stock carb and I will do my best to get it close...

I really appreciate it Chef but I spent the money on my truck....:D

Unless you wanna put me on the easy payment plan and I send you $25 a week....:devil:

[nakomis0]

When you say you tried a bunch of jetting combos.... you played with the needle settings?

[speedy400]

Well, someone helped me out at C&D racing very very much, turns out the little needle to let fuel into the accel pump is just jammed up there with no way of getting it out it seems, so, if any one has any problems like me, check that, its the little brass needle thing in the hole on the bottom of the bowl, you can see it when you take off the accel pump covor. and to answer the previous guy's question, yes I did mess with the needle, slow jet, pilot jet, and the fuel/air screw.thanks-darren