My '05 KX wasn't running real good, esp on the low end and I was thinking "jets". I thought I'd take a look at the plug and when I did, immediately noticed how easily the plug cap removed. "That ain't right", I thought to my brilliant self. So, I tested the cap with a spare plug and felt it "click". Back on the bike, it took a lot of force, but it did "click" on the plug and it was ON. Started the bike up, took a spin, and ta-da....low end power is back. In fact, I was pulling low speed wheelies around my play track. MUCH better!
File this away FYI.
:cool: