Geeeez, I'm glad I didn't know this much some years ago. My '78 muffler
brackets broke in such a way that it allowed me to slide the muffler off of
or onto the connecting pipe (no catalytic converter), so I could have
muffler and quiet or play "hot rod" and go deaf. My mileage was marginally
better on the freeways, but once in town, I'd stop and slide the quiet
thing back on and play innocent. I guess the fire gods didn't deem me
acceptable for consumption...

steve
'85 westy
kent, wa

At 07:11 PM 09/10/2000 -0700, Daniel Schmitz wrote:
>My understanding of running an engine with insufficient backpressure is
>that it can cause the exhuast gas to exit the combustion chamber too
>fast, which can burn the exhaust valves. The velocity of hot gases
>flowing past the exhaust valves and through the exhaust port too fast
>can actually cut grooves into the exhaust valve.
>
>But there could be other reasons, as well.
>
>Dan
>