CR125 2002 refuses to idle

[askimo]

I have an issue with my bike that simply prevents me to ride it a low rpm’s. Basically the bike is very slow to respond and bogs (engine makes a booooowah sound when you open the throttle from 0 to ¼). After much reading in internet (http://justkdx.dirtrider.net/carbtuning.html and http://ericgorr.com/techarticles/carbtuning.html) I found that, contrary to what I was thinking, this is a clear sign of running too lean because engaging the carb's choke to the halfway position fix the problem. However after following the guide described above I could not permanently solve the issue even after position the jet needle to the richer position and closing the air screw as much as possible.

Also I tear down the entire top end to check the engine, but the cylinder and piston were like new (low hours and never raced bike) and only the ring, pings and gaskets were replaced (with all the fluids)

Any ideas or recommendations?

[Meh]

Up your piolet Jet...

[askimo]

Thanks for your reply

Yes is something that I'm looking into. Also the plan is to replace the low jet as well to see if makes any difference. Is any way to determine if you any air leak coming from the crankshaft?

[blaster911]

yea pilot jet is deffinitly the problem

[askimo]

The standard pilot jet is #400, should I go for 410 or jump directly to 420?

Would be wise to play with the slow jet as well?