What do you do next?

I'm working on Mark Albertson's Suzuki 1100 he bought from me (in the pic). He's only getting 29 mpg. My 2 get a minimum of 45 up to 55. Avg. of 49. I used to get low to mid 40's with his.

So far I've rebuilt the carbs 6 times, checked the ignition advance, looked for leaks, checked the float levels and lowered for economy, dropped the jet needles down to lean it out too. Also checked the air filter, it is clean. No obstructions in the intake. The throttle valves and internal vacuum system system seems to be working ok.

The spark plugs are very black, he says is runs worse now at low speeds. He's slowed down to 70 on IH-10 from 80. But his gas is red??

Yet to do. Check valve clearances and valve timing. See if exhaust system is plugged. See if tires rotate freely, and brakes are not dragging.

If this doesn't do it, what do I do next?

Right now Mark has my 91 with 97,600 miles that runs better than his.