Long PCR Primers

[Sandra Pena De Ortiz]

I am thinking on using a 40 bp long pcr primer.  I need to add a 
consensus Kozak sequence for expression and want to add a bamhi site to 
ease cloning.  Does anyone know if a primer this long will work?  The 
longest I have tried is 26 and had no problems.  Also, how many bp minimum 
should 
I add 5' to the bamhi site to ensure binding and cleavage by the enzyme?

Thanks in advance,
Sandra Pena de Ortiz, Ph.D.
Dept. of Biology, UPR