I got an Edelbrock about 4 months ago ( New) and it had always been set to rich. Plug was black. I adjusted the mid to low range using the knob on the top of the carb. Wasn't running bad but I knew it was not set right. Finally I decided to go to a leaner needle. The carb was advertised to be set for the XR650R. The instructions said how to change the needle but to refer to the XR650R spec sheet for specific specs. The spec said I should have a 17 E needle and 12 clicks. What I found installed was the 19 E needle and that was the problem. I set the 17 E at 16 clicks( wanted it to be a little on the rich side). Runs much better, better throttle snap. I thought it was good before, except for the black plug. Now it is WOW! 73 degrees F Sea level UPDATE 10 /16/05 I checked the plug after the above change of the needle and it was a nice tan color. But it was popping on deceleration. So I moved the idle to midrange clicker to 19 clicks. I will run it again and check the plug. I also moved the mounting clamps on the carb around to the bottom so I can loosen the clamps and rotate the carb for future clicker changes. I was taking the tank off to get to the adjuster on the top of the carb (clicker) for the idle to midrange.