Carb icing will be a problem with non-preheated carbs whenever the 
outside temps approach freezing: like around 3 - 5 degrees C and lower.

At these temps, the venturi effect will allow water vapour from the 
outside air to freeze in the carb throat, cutting your engine out.  Can 
really blow your mind if you don't realize what has happened.

Tobin
Who prefers to blow his mind in different ways...   *:-)~

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Tobin T. Copley                  Only Somewhat          =============  
(604) 689-2660                    Occupationally       /_| |__||__| :| putta
tobin@freenet.vancouver.bc.ca      Challenged!        O|             | putta
                                                       '-()-------()-' 
Circum-continental USA, Mexico, Canada 15,000 miles... '76 VW Camper! (Mango)