As LAB says we really need clarification as to what is going on here. Was everything OK before you did your most recent change or is the whole bike new to you? Have you got single or twin carbs and if twin are they synchronised properly? Assuming that is OK does the bike rev up OK whilst stationary and not under load?
Are the chokes and slides opening up fully?
Are the needle clips in the right grooves.
Are the air filters clogged, is the exhaust clogged - do you have mice living in there?
If it does that OK but won't pull away, you might have a chassis problem eg over-tight chain/s, seized chain or seized brakes?
If you can be more specific we can be more helpful