03 crf450 wont start

[YZ 250F]

Hey guys,

Ive got a 2003 crf450r. I bought the thing, didnt run, replaced the entire engine, except carb and transmission. I took it out to the track a few days ago, and after a short break i went to start it and it wouldnt start. So i broke it all down again. I have spark, compression, air and fuel. So i figured its valves... nope valves are perfect. So confused, i broke into the carb. The carb is totally clean as well, but it starts pouring gas out everytime i try to start it. Needle jet? Bad float? Im lost. Thanks guys

[nzgsr]

Gas pouring out the overflow is typically a worn float valve, or incorrect float height.

[ThrustWasher]

Hey guys,
Ive got a 2003 crf450r. I bought the thing, didnt run, replaced the entire engine, except carb and transmission. I took it out to the track a few days ago, and after a short break i went to start it and it wouldnt start. So i broke it all down again. I have spark, compression, air and fuel. So i figured its valves... nope valves are perfect. So confused, i broke into the carb. The carb is totally clean as well, but it starts pouring gas out everytime i try to start it. Needle jet? Bad float? Im lost. Thanks guys

If it has spark, fuel and air it would be running. What you're saying doesnt add up.

[YZ 250F]

On 4/8/2018 at 2:18 PM, nzgsr said:

Gas pouring out the overflow is typically a worn float valve, or incorrect float height.

Thats exactly what it was. Worn float valve. Thanks brotha

[YZ 250F]

Final answer:
•Flooding out of the overflow when it is being kicked is caused by the wrong float height.
•It can also be caused from a bad needle jet... the rubber tip on the needle jet be smooth and in a V shape. The needle jet is responsible for stopping gas flow. Once the bowl is full the float pushes down on this little guy, in turn, killing gas flow.
•Make sure when you are putting the carb back together, make sure that you dont put the vaccuum plate in upside down hahahaha. Rookie mistake
•While you are in your carb, check your acc pump. I bet it needs to be replaced. It should have a spring in between the cover and the smooth rubber circle.