Speedo, make sure that the air cleaner rubber and the carb throat are DRY. No oil of any kind on eather surface. Do you have the correct size for your carbs?
Are you using K&N clamps?
Hope you sort this out, when you do please post! Regards~ Jim
as James said, make sure all the oil is off. Also too tight doesn't work. You have to find the fine line between too tight and not tight enough. If its too tight, they will pop off. Just play with it for a while. Tighten one a bit and then try to "jiggle" it with your hand. If it feels secure, tighten a bit more. Pull on it and see if its staying, if it does then great. Also what you can do so at to ensure you don't loose them. Wire them to your carbs. Just one tinny hole in the filters wont affect the performance and if it falls off, at least you wont loose it.