Bonneville Loss Of Power

From memory, on my old T100 there was a hidden filter between the carbs in the fuel feed line. I took this extract from The New Bonneville Riders website as it explains it quite well.
"Not sure on the T100s (yes) but on the America and Speedmaster (I imagine this holds true for T100) - yes - there is a hidden filter between the carbs that can cause problems. Follow the fuel line from the gas tank to where it hooks to a T between the carbs. Pull the line off there and in that T should be a small filter. Clean that or even better get rid of it and put one inline.

Also try leaving your gas cap loose and take a ride to be sure your tank is venting properly. If leaving the cap loose helps look at the venting system.

You should also check your float level get a small piece of clear tube that fits the drain nipple on the bottom of the cab bowl, with the bike sitting up level (like on a bike jack) hold that clear tube up along side the carb and open the drain. The tube will fill to the level that is in the bowl. It should be just about at the seam where the bowl meets the cab body."

 

There is indeed at the T piece.

 

I had similar issues on my 2005 T100 that turned out to be a failing coil. In the diagnostic process I discovered a teaspoon of fine brown rust 'sand' in each float bowl and a partially clogged inline filter. If you have not had them off, you might find it a worthwhile late spring clean along with a tank flush.

 

Yup the small white rod. And my ignition coil only sputtered below 3,000 rpm which threw me for a while.