bogging FCR

[bigz-71]

i have an FCR carb installed on my 450r and i have a bogging issue. it only seems to happen when i land hard off of jumps. this past weekend there was a rythem section that i could not double through and i had to single and land hard into the next one and everytime i hit the next one the bike wanted to bog on me. i was wondering what would fix this problem. i figured my jetting is off just a little so i thought maybe one of those fuel/air screws would fix the problem.

what do you guys think?

[bigz-71]

i have seen accelerater pumps but do they really work?

[400exBro]

i am also struggling with the same issue, haven't got the bog to go away.
what is your jetting?
I am running a 170 main, 48 pilot and stock on the needle. I have a sparks full system, open air box with the sparks air filter kit and an 03 fcr carb off the crf bike....

[86atc250r]

Is your TPS wired correctly?

I've never had mine bog on any occasion.

[400exBro]

Originally posted by 86atc250r
Is your TPS wired correctly?

I've never had mine bog on any occasion.

Mine is wired correctly we checked...
i only have bogging issues going through whoop section that require some throttle control, and timing other then that it seems to run fine...

[86atc250r]

That's right where a TPS issue would occur - any part throttle setting or transition.

Anyhow, if you've not only checked the wiring against a known good diagram (there are bad examples being presented as good out there so be careful of which you use), you've checked that resistance is both within spec and changes correctly with throttle movement between all the leads, you'll need to make sure that the splash plate is in place around the main & then start checking into needle settings.

I've also seen what appears to be very small black plastic shavings from the tank make their way thru the fuel sysem to play havok with the carb.

[400exBro]

Originally posted by 86atc250r
That's right where a TPS issue would occur - any part throttle setting or transition.

Anyhow, if you've not only checked the wiring against a known good diagram (there are bad examples being presented as good out there so be careful of which you use), you've checked that resistance is both within spec and changes correctly with throttle movement between all the leads, you'll need to make sure that the splash plate is in place around the main & then start checking into needle settings.

I've also seen what appears to be very small black plastic shavings from the tank make their way thru the fuel sysem to play havok with the carb.

I used your wiring diagram(or cross refrence) you posted over at trx450r.org, so i asumed it was right.
i haven't checked the reistance at different throttle postions, would you happen to have them on hand? or are they the same as the stock carb?
And if everything checks out right, should i move the needle up (bring the clip down) or move the needle down( bring clip up)
thanks for your help.

[86atc250r]

Yes, that diagram is correct.

Yes, the numbers should come up the same as stock.

Don't remember off the top of my head, but the initial (closed throttle) setting is in the service manual & in some posts over at .org, somewhere.

You can double check the TPS by verifying the resistance goes the correct directions according to my cross ref post.

Sounds like you may have already covered those bases.

Make sure the plastic splash shield is in place around the main -- I've almost forgot to reistall mine before.

Next step (if you're pretty sure the needle is somewhere close) is to take the carb apart and check for any debris (black plastic shavings) that may have lodged themselves in the main, may be floating around in the bowl, or are in the needle jet. I know several people who have had bogging trouble with the stock carb and found the little black shavings as the cause.

[400exBro]

i just had the carb apart last week to change the main jet and pilot becuase i was too lean on the slow circut and to rich on the main jet circut. So the little plastic thing splash gaurd is around the main jet and there was no debrie in the carb.
I am going to check the reistance on the tps, if that doesn't work i will try the needle, the clip is still in the stock position, i am thinking it may be a little to lean, and that is why i get the bog.

thanks again for your help.