If you get pulled over, the response you'll get is unpredictable. It'll vary from:
"show us your license.... now be off with you"
to
"show us your license. That's a 100TL fine"
"show us your license. Oh look, you're foreign, that's a 400TL fine"
I understand if you do get a fine and don't pay it, it can get difficult at the border, but that's not happened to me so I don't know.
Best bet is to keep off the 'main' roads (the equivalent of A-roads in the UK, stick to motorways (no one seems to give a flying feck about speed or driving skills on motorways), keep an eye out and/or keep the speed down.
Remember, 90% of the time, an A-road speed trap is marked by way of a little triangular warning sign at the side of the road and then a cop standing with a speed gun by his car somewhere over the next couple of miles. Not too difficult to miss if you keep you eyes peeled. Other coppers won't have the instruction or know how to stop speeders, so you have less to worry about when you see cop cars (which are everywhere).
Also remember the "Foreign" card can go for or against you. If you are lucky, they'll let you off because you are more hassle than you're worth. If you're unlucky, they'll decide you're worth more than the hassle and give you hell.
I've never been stopped for speeding, but I have been stopped for covering my number plate with masking tape to avoid the toll. Survived a week, then got pulled over. I pleaded ignorance and no Turkish, so the policeman waved down another biker who just so happened to be able to translate. A bit of sweet talking later and I'm on my way with a stern frown.
So my advice would be to get a few basic words of Turkish practised (Turks love foreigners who make the effort), have all paperwork etc. to hand (it'll make you look innocent and may bamboozle the copper) and be as innocent and niaive as possible. And if that fails, take the hit, pay the fine and enjoy the scenery at a slower speed.