I want a sports bike. im a big guy. whats a good bike to start on?

A 250 ninja has no problem with a 150lb rider and 150lb passagner. This is a great beginner bike that even most motorcyclists don't know from a full on sport bike. Full on sport bikes require real skills. If you buy an expert electric guitar you don't die when step on stage and don't know the first thing about playing, but a 100hp motorcycle will kill you if you don't have finely tuned skills and a boatload of experience. A guy died in town here just last week wiping out on a very easy curve with a 25mph speed limit. Start with the right bike and have more fun.

Go for a big ole fat harley davidson!

Wooh. I'd say start on a 250 the same as everyone else but in your case you might have a legitimate need for a little extra engine power. Take the MSF course though.

Forget true sports bikes until you have learned how to ride, you won't gain anything extra that you couldn't get from a milder and more forgiving sports-tourer. Cheaper and safer too. I'd suggest the old Kawasaki GPZ 500 (misleadingly called the Ninja 500 in the USA) or - as much as it pains me to say it - the Yamaha Diversion 600. Normally I wouldn't recommend a bike that big to a beginner but the 600cc version has an engine that runs as flat as a pancake. Nothing wrong with the 600cc Diversion, it's just dull and slow, which for you is a good thing.

Why do you want a sports bike? Head down arse up the most uncomfortable way to go any where. Sit up will allow you to ride better and more comfortable and give you a much better experience. So out round the bike shops there's plenty of them but do look at the BMW's as there's some good 2nd hand stocks out there. Once bought your unlikely to change as 'it' will do what it says on the tank!

if you can find a used 1,000cc sport/ touring you will find a bike that should easily take your weight and height into account. Because it says sport touring as well the insurance should be less to deal with. If you try to insure a sports bike the cost increases because the insurance folks know how those are ridden, and price it accordingly.

A 650 WILL do, but a 1,000 will be better. I do recommend a cruiser as a 1st bike, they are more rider and insurance friendly. After a cruiser, a NAKED sport, the sport fairing will do nothing for you and they are expen$ive to repair.