CRF's Only Forums

Have a 2004 CRF80 in great shape. It starts immediately and runs as long as the choke is on. As soon as the choke is turned off it dies.

I have cleaned the entire carb (2x) and installed a carb kit with new gaskets and new jets (#95 pilot jet / #35 main jet). I have adjusted the fuel mixture screw multiple times from 1.5 to 2.75 turns out with no change regardless of adjustment.

There is also no change when I lever the choke - it's either all or nothing. The bike starts and runs at high RPM when the choke is on from fully, 3/4/, 1/2 or 1/4 of the way open. No change regardless of position. As soon as I turn it completely off the bike dies - even with the throttle pumping or held wide open.

I have also checked the petcock and verified fuel is freely flowing. I adjusted the valves to spec (.05 MM) and have checked for intake manifold and vacuum leaks. None can be found. I am 100% sure this is not a clogged carb or pilot jet problem. The carb is clean and all jets are new.

Am I missing something else?

Hi and welcome to the site.

When the lever is down the choke is off.
Is that your understanding?

I only ask because I have had people before thinking it was the other way around.

How long have you had the bike?
Is this only a new problem?
How old is the fuel?

Have you done any work to the bike just before it started playing up?

The lot of questions I know but it gives everyone an idea where things are at to help diagnose the problem.