Runs rough

[lgibson]

My 99 valk has recently started running rough but only on the highway. Around town ite fine. It feels like it gets down to about 3 cyls. I recently put an IS tank on it but didn't flush it out.I'll probably have to flush it out and what about the carbs?

[Attic Rat]

Check the petcock it could need a rebuild kit

[Michvalk]

Check the vent line. Could be kinked from adding the different tank

[Patrick]

All of the above. Plus, open the drains on the carburetors and flush them.
Start there and see what happens, let us know.
We'll go further if needed.

[gordonv]

Since the tank is the most recent thing done, I would suspect contamination from there first.

Because I'm lazy, I would start with half a tank of fuel and a FULL bottle of your favorite carb cleaner (Techron, Seafoam or Berry's B12). Run it low and high RPM, and see if it changes at all.

If no joy, then I would start from the top to the bottom, and flush everything out, like already mentioned. The tank, verify the petcock is functioning as it should, and drain the carb bowls for any contamination to come out. Make sure you capture your drained fuel, and inspect for contamination, so you can satisfy yourself that it could/was the problem.

Then post your results, and see where to go from there.

[lgibson]

I took the pet rooster apart and there was some trash blocking the fuel flow. Thanks once again guys.