05 CRF 450 won't run once choke is off

[USMCThumper]

Hey guys,

Looking for a little help with the carb on my CRF450. I'm located in NC at sea level, temp was just under 70 deg today. It's a stock bike with a new topend and valves about 10 hrs ago. Bike ran great 4 months ago, but hasn't been ridden since. I got the bike out this morning and kicked for about 20 min, nothing. I pulled the float bowl off and sprayed carb cleaner in it to clean it out. I put it back together and it started 3 click with choke on. As soon as I turned the choke off, the bike stalled and wouldn't start without the choke on.?

So I took the bike apart, then pulled the carb apart, sprayed carb cleaner in thru the top and blew everything clear with compressed air. I also checked the float bowl & level, no issues. I put the bike back together and it started 1st kick with choke on. The bike sounded really good, so I pushed in the choke and it immediately died. I pulled the choke again and the bike fired up 1st kick again. I decided to ride with the choke on for a minute or two and rode the bike up and down the street. As I came back around to the house, I pushed the choke back in and the bike rode good for a second. Unfortunately as soon as I would let off the throttle, the bike would just die. I tried to start the bike with no choke and it wouldn't restart. As soon as I put the choke on it starts 1st kick and runs good.

I have the JD Jetting kit in it with the red needle, fifth clip and 178 jet.

Bottom line is the bike won't idle/run without the choke on.?

Any ideas/suggestions??

Thanks

[William1]

Replace the pilot jet, cleaning is often fruitless.

[squiresharpe]

Mine did the same thing. It was an air leak where the hot start attaches to the carb!

[JJRace]

You need to remove the jets and do a good cleaning of the carb. Not just spray cleaner in the bowl and on the jets.

Remove the jets, clean them with carb cleaner, then spray with compressed air out. Check them! point them to a light and check they are clear! Then remove the fuel screw, blow compressed air and carb cleaner through the main/pilot and also the AP circuit and all 1 way valves in the bowl and carb body. Then remove the choke and hotstart plungers, clean, grease and reinstall. Then put the carb back together, adjust the hotstart cable to make sure there is slack in it.

Most likely it is the pilot jet being plugged is the main source of the problem. But never hurts to clean the entire carb up!

[USMCThumper]

You need to remove the jets and do a good cleaning of the carb. Not just spray cleaner in the bowl and on the jets.

Remove the jets, clean them with carb cleaner, then spray with compressed air out. Check them! point them to a light and check they are clear! Then remove the fuel screw, blow compressed air and carb cleaner through the main/pilot and also the AP circuit and all 1 way valves in the bowl and carb body. Then remove the choke and hotstart plungers, clean, grease and reinstall. Then put the carb back together, adjust the hotstart cable to make sure there is slack in it.

Most likely it is the pilot jet being plugged is the main source of the problem. But never hurts to clean the entire carb up!

I did all that and still no idea what it was. No issues with anything I hadn't already cleaned, pilot was new. I put it all back together today and it started and ran like brand new. I guess it just wanted to be taken a part completely.?

Thanks guys!

[Motoxbaeza]

I've had a ton of pit bikes do this, it' gets tougher on smaller bore carbs, bikes that shut off as soon as the choke is off is a tell tale sign of plugged pilot and so on. Bad GAS

[vector911]

mine did the same thing after putting the JD jet kit and cleaning the carb up. I pulled all the jets and made sure they are 100% clear. It fired up pretty quick. A few fuel screw adjustments later and it's back to normal easy starting..

[yz400fdude]

My old bike did the same thing. The jets were clean, the problem was some dirt got lodged in one of the fuel passages. As a side note, I couldn't see the dirt in there, a friend figured it out.

[fastestoldwheelieguy]

Semper Fi devil dog! USMC 1967-1971 here. Just FYI, in the future, when cleaning the carb, take a thin piece of safety wire and physically poke it through the orfices of the main jet and ESPECIALLY the idle jet. Dirt or a piese of sand can get lodged in the idle jet easily mainly because it is so small. Sometimes compressed air and/or carb spray will not knock them out. If you don't have any safety wire, you can use a bristle off of your shop wire brush. Just make sure all the orfices will allow it to pass through. The smallest particle can really gum up the works!!