Invader, thanks for your help. I adjusted the left t/b through trial and error. It took 3 attempts, r/r the tank and air box, turning screw, back together and measuring balance. I had to unscrew it 3/4 turn which brought the levels from almost 3" difference to about 1 3/4 to 2 inches. I noticed right away it idled smoother...........rode it around a little and a definate improvement in drivability, no intake backfire (so far!) I will leave it alone until the the next air filter service then I will turn the screw out another 1/4 to 1/2.