Karl Szczypta wrote:

I have seen the pop-off valves for the 911, but never
bothered to buy one for mine.  Any insight into how to
avoid a backfire?  I have had my 911 for a long time and
no backfires.  Maybe just lucky.  Perhaps some years or
other variations are more likely to backfire??

*snip*

Bill

Bill,

Yep your just lucky. Sometimes when the 911 burps it just cracks the
box which may not do enough damage for a performance difference. Well
at least the first time it happens. The pop-off valve should be put in all CIS
911's. One other point to note is that with the valve if you do hear a bang the
air filter should be checked for burns.

As I remember it the problem is the cold start circuit which adds fuel when starting
a cold engine.

Karl

 
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