what does my licience cover?

[suspectmonkey]

My full driving licence lets me drive a moped up to 50cc

Yep!

proper bike you have to do either a light bike test (Cat A1) lets you use bikes up to 125cc

Apparently so, although I've never actually known of anyone doing the light bike test, most people just do the full bike test.

your full bike test (Cat A) lets you use above 125cc (although you're restricted to 125cc for the 1st 2years).

True-ish.  You can actually ride a bike up to 33Bhp in your two years so it doesn't have to be 125cc.  For example, Kawasaki make a 250cc "sports" bike that comes in within the 33Bhp restriction and is legal to ride for the two years.  Or, you can have a restrictor kit fitted to a bigger capacity bike.  For example, my dad bought a Suzuki V-Strom 650cc when he passed his test, and GS Suzuki fitted a restrictor kit for free which reduced the horsepower to 33Bhp.  This makes the bike fully legal to ride, but you get to enjoy a bigger bike and they still have plenty of go in them.  When your two years are up then take it back to the dealer and they will pop out the restrictor in a matter of minutes (and usually for free) and you have the remaining horses unleashed.  Many people (ahem ) don't even bother restricting... but obviously this is very illegal, invalidates your insurance and very irresponsible...

Your original theory test is transferable so all you have to do is the practical. Simples!

Not true in my case, I had to resit my theory the same as Craig even though I had a full car licence.  In my case the theory test was new to me anyway as there was no hazard perception when I sat my car theory.  As far as I know theory tests are category specific, and therefore have to be undertaken any time you want to add a category to your licence.

Truth be told, its not half as complicated as it all sounds though.  Best thing to do is buy a "package" of motorbike lessons with a driving school and go for it.  I bought a package of 10x lessons through Ians School of Motoring in Newtownards and that gave me full use of a 125cc bike, helmet, gloves etc. including an hours lesson before the test and use of the bike for the test.  I'd definitely recommend doing a bike test, even if you aren't going to use it immediately its worth doing now if the CBT is imminent.  At the very least, even if you never use it, it opens up a whole new perspective on driving  

[MG1]

I drove a 125 bike for years without a cbt and was fully insured. We you pass your full bike test i think your restricted to 400cc for the first year or maybe 2. Saying that i haven't owned a bike for a bout 4 years so this might have changed.

Chris are you going to start wrecking bikes now instead of cars?

[chris]

I drove a 125 bike for years without a cbt and was fully insured. We you pass your full bike test i think your restricted to 400cc for the first year or maybe 2. Saying that i haven't owned a bike for a bout 4 years so this might have changed.

Chris are you going to start wrecking bikes now instead of cars?

That was one time! And it wasn't even really my fault, that dog just jumped out on the road I had to properly swerve to make sure I hit it!