Strange noise coming from my exhaust.

I have a 4th gen. I've noticed in the last few thousand miles a strange noise coming from the exhaust end, at idle. It sounds like continual intermittent "spitting." That's the only way I can describe it. The bike runs well although yesterday when I rode it and stopped, the bikes exhaust spitting was very loud.

Hasd anyone any ideas what it might be?

 

Only thing I can think of is a rust hole on the bottom of muffler.

 

The spitting sound is coming from the exhaust exit, not anywhere else.

 

Stock exhaust? Shine a strong light down the muffler and see if you see anything.

 

Mine might be doing the same thing, although I could describe it as an intermittent sharp tapping or popping because the sounds are very brief. I made a recording with my phone but still have to check it out to find out if it's clearly audible, might post it if it's useful.

 

It may be a misfire. What is the condition of the plugs?

Just one test: Hold a dollar bill against the exhaust, it should push outward constantly. If it gets sucked in that could indicate a stuck exhaust valve and the inlet stroke is sucking exhaust back into the engine.

 

Tried the suck-back test

I did the suck-back test today on my '95 and posted it to Youtube. It really sucks the (20)dollar bill back hard. Jim, have you tried this yet?

http://youtu.be/Dqc3v2rPC0A

 

Still trying to filter the audio to isolate the frequent but intermittent click/snap/tap/spit sound. But Lord it still hauls on the 401, especially on cold days like today !