Posted: Thu Aug 09, 2007 1:43 am
Unless you have changed the gear ratio & carb belts will snap- game over- ALOHA 
Check your front and rear pulleys for rust.
Also, check your rear pulley for excessive play and/or cracks.
Check your weights too.
Keep your rear pulley uncovered (removes heat).
Try a stock belt and see if it shreds.
"Kevlar" sounds nice but I'm not sure what the material properties of Kevlar has to do with the material properties you want in a drive belt. Do you see "kevlar" belts advertised in automagazines?
"Kevlar" sounds like "pay more for a * product" to me.