Ive done the spark plugs its got a K n N in it might that have anything to do with it and it only got normal petrol not v. Power some one said the cdi is wearing out ?

Oh and its got a leak on the down pipe

Not the CDI, they either work or they don't.

So it ran OK when you were on it and the engine was cold ?
It starts OK ?
The exup valve works OK and there's a weep weep noise when you first turn the key ?

Yeh sounds like there a chick in the engine lol runs ok when cold once its hot unless i rev the hell out of it, it hesitates and doesnt rev over about 2 and a half thousand when i pull the clutch it cuts out

Have you checked the coils,Sounds like one is breaking down.

Where are they

And how do i check if its not missfireing is it the coils ?

I reckon its a fuel thing. Could be the filter the fuel stirs up the shit in the filter but it takes a while to partly block it so it runs and warms up then it choacks off. It can also be a kinked fuel hose. A dirty fuel tank blocking the fuel tap use a torch to check for any sediment.
Lastly check the fuel tap is FULLY turned to run use pliers to turn it it breaks if you use a screwdriver.

Nothing to do with the KnN filter and it having loads of engine oil

Have you checked the valve clearances?
If they are tight they can cause running problem when hot.