Carb settings

I have an 04 450 with an FMF complete Titanium exhaust. My bike has always ran great except for the last couple times :devil: When I gas it right from the bottom it hesitates or will even stall :cry: Its never done this before, so right away I drained out the gas and that did nothing :cry: This is my first four stroke and I'm still trying to figure out the differences. :devil: I have a Zip Ty fuel screw and went in both directions in adjustment and that did absolutely nothing. :cry: The bike didn't run any different if it was screwed all the way in or 5 turns out :D

If you punch it right from idle the bike stalls now. :cry:

this is how I have the Carb set from FMF's recomendations. It ran great this way for 2 months. What can change???????? Help PLEASE!!!!!!!

42-Pilot

165-Main

3d groove on the needle

1.5 turns out-Fuel screw(Doesn't matter what direction or how many turns. Runs the same way!!!!!!!!! :cry: )

Unscrew your zipty screw all the way out and see if the tip broke off in the carb...

This happens pretty regularly when people seat them too tightly.

If it is, I have heard of Zipty getting them out for people, and usually giving them another screw too. Call them.

If the screw is ok, you may have just gotten the pilot jet clogged up with some trash. Give the carb a good cleaning with carb cleaner and some compressed air to blow out all of the jets and passages.

I've never heard of the zipty screws breaking, but if it did then that could definitely cause a problem! I'm voting for clean the carb out good, sounds like you got some goo in the pilot circuit somewhere.

If you punch it right from idle the bike stalls now. :cry:

this is how I have the Carb set from FMF's recomendations. It ran great this way for 2 months. What can change???????? Help PLEASE!!!!!!!

42-Pilot

165-Main

3d groove on the needle

1.5 turns out-Fuel screw(Doesn't matter what direction or how many turns. Runs the same way!!!!!!!!! :cry: )

In cooler weather you need to raise the needle to clip 4 or 5 and put in a 48 pilot to richen the off idle circuit. Also put in a #40 leak jet in the bottom of your float bowl. You are experiencing a lean bog. Very common on the Yamaha 450's with colder weather. :cry:

Also how big of adjustments are you trying? You should be about 1-1.5 turns out on the screw. Adjust slowly in 1/16 increment turns. It is VERY sensitive.

Yeah I'm only turning it very slightly. It makes no difference at all. I checked the screw and all the parts and they are fine. I'm gonna clean my carb out and see what happens. Thanx for the help :cry:

I'm in Arizona so it only gets down to about 55-50. Do you think that is enough of a difference to have to rejet? I never messed with the jetting on my 2 stroke. Are the 450's that sensative to temp changes :cry:

Thanx for help and advice :cry:

Thanx for the help :cry:

I'm in Arizona so it only gets down to about 55-50. Do you think that is enough of a difference to have to rejet? I never messed with the jetting on my 2 stroke. Are the 450's that sensative to temp changes :cry:

Thanx for help and advice :cry:

Absolutely very sensative to temp changes...jetting and adj zipty will solve...

My 450 runs liketotal crap below 45 so I do not ride at that temp period - JD jet kit solved this issue with me. Red to Blue needle changes and larger main for cooler temps

Hey Dune, Where at in AZ? Im in Goodyear off I-10 & 303. My cousin is battling the same prob with his '04 CRF450. It popping real bad, and we have been messing with the carb settings. He has the White Bros carbon fiber racing series pipe, and he has been messing with jets like crazy. We have it running a 170 main, and the popping reduced a bunch, but its still there, also, there a hesitation off the start, almost like a delay. Still trying to figure this one out...

On that crf sounds like the valve are going there good for that on the yz i would put the needle back to stock i move it to #3 and had the same problem:applause:

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