Noise - Exhaust leak or lifter?

[Furbo]

Have an odd noise on a 79 Westy. Stock engine, newer stock muffler & gaskets back to the head.

It sounds slot like a small exhaust leak, except that you don't hear it at idle. It sounds some what like a loose valve as well, a 'light' knock but not the metallic 'tikca' that valves usually make. Have gotten under the engine with it running and can't detect exhaust - am somewhat baffled. Doesn't seem to effect running.... Any good ideas?

[raygreenwood]

If its the stock type muffler, this type of exhaust leak is usually at one of three places (1) either you have a header tube gasket right at the head that is not seating.....or it could be a loose exhaust manifold stud in the same location (2) An internal crack in a baffel area (one of the most common and impossible to see) (3) A flange gasket with a small leak that only reaches to the outside when pressure are high at higher rpm.

Most of these problems are caused by flanges that are warped or welded so they are not planar to each other...or exhaust nuts that were heavily overtightened so that the gaskets are too crushed. Ray

[oilhammer]

Very common for the square port heads to crack at the exhaust flange and leak there. My '82 has that same problem now