Idles good, not good at highway speeds

[Whiskerfish]

With a problem like this your plugs should tell you if it is a starvation issue or a spark failure. Duplicate the problem for a bit then do a plug chop. If they are wet and snotty then look at the ignition system. If they are grey/white then a fuel lean condition.

[chowell]

While the carbs were being rebuilt I drained and removed the fuel tank. I was going to clean and por 15 the tank. I discovered that someone had beat me to it. It was already cleaned and coated. I also flushed the fuel pump before refilling the tank after carb reinstall.

[jdvorchak]

First what?

[chowell]

It looks like my problem was clogged fuel pickups in the gas tank. I got a good looking used tank out of a 1983 and put it in this week. Took it out for a ride today and it ran very good. No misfire. No stumbling. No backfire. Just smooth.

The PO coated the inside of the tank with some stuff that's the same color as Pepto-Bismol. When I looked down in the tank I could see both the main and reserve fuel pickup screens were part way coated with that stuff. The coating stuff may have gotten into the fuel pickup tubes but I couldn't tell.

Thanks to everyone who replied and helped me with this diabolical problem. Especially Whiskerfish who told me how to diagnose the difference between fuel and spark problems. I'm glad I put new coils and a fuel pump on it anyway even though it didn't really need it. Got it fixed just in time for riding season to begin here in Florida!

[Track T 2411]