adam bike doctor?

right then mate ive ended up replacing the piston ive stripped her down and put her together again and set every thing to stanard as it should be in the service manual i started her up and she sounded sweet (she started first time) so i took her out she seems to go better than ever before real smooth pull away,no flat spots ,and i can feel the revs better and it just seems really sound ,but she is smokeing real heavy and its white smoke,and not just the normal 2 stroke smoke i mean a lot except the pump is set to the standard settings in the book ,im using tts oil in it but what would cause this im using an 8 spark in her for winter ? i really need your expertease as ive booked her in for a proper sevice and tune up in mtc which is one of the better bike shops in my area as it bein off the road has cost me a fair bit as not bein able to go to work and now im gettin kind desperate......please help!