Unless it's Italian...then it's made of sugar.
I bought this one from Walmart : http://www.walmart.com/ip/Classic-Ac...-Cover/5982680
works great. kept my bike dry from a downpour.
2009 Daytona 675
2001 DRZ400E Streeted
www.SouthandBack.blogspot.com --> Argentina to Canada, KLR 650
I use one not for the rain but for the crap coming form the highway. If i don't cover my bike, it gets filthy as shit the next morning. That and pollen. Amazing how much pollen dust on my cover each morning (during the pollen season that is). Aaaaaaaannnnnddd to protect it from the sun if i'm not riding. Sun is really fucking things up. You should see my son's plastic tricycles. Left them outside on my deck a few times and the paint is already pale.
Using a cover on a dirty bike is a definite way of picking up scratches.
If you want to cover it to prevent theft and vandalism then you need to cover it with a compact when compressed style.
Whenever you cover it be very wary of wind storms not just for flapping covers scratching your bike but for it knocking your bike over.
I use this for travelling , expensive but worth it when you want to protect your bike from malcontents. If I can see the cover being used as a security device why bother at all. They just take up room and are a PITA
Different versions available
if you go in this direction (even though most have recommended not needed), cheapest cover you can find that's waterproof. I have a cheap $20 and it works wonders. I only use it for storage though. The rest of the stuff is just marketing gimmick cr@p. A cover is a cover, a bike does not need to "breath". It's not a damn mammal in a cage.
Current: 2009 Suzuki GSX-R 750
Retired: 1999 Yamaha R6, 1989 Suzuki GSX-R 750
Condensation under your cover is what rusts all that nice electrical stuff your bike needs to keep running well. A good Guardian All Weather cover has a small hard plastic vent in it to allow some air flow to get rid of it. It's got eyelets to allow you to lock it onto the bike, and the underside has felt to keep it from scratching the windshield and fairings. If you don't have a garage, it's the best you can buy. $122.99.