Did you do all that at once?
A ported cylinder needs a highly modded head. A shaved head alone will not do (99.9% of the time).Check the compression...
If all is OK, then put the stock carb back on and see if it runs.
The 20mm carb is not great.
What did you do to the clutchs for that motor?
2000 GNC 5N\
2001 GNC 9N \ 40+ class
2004 GNC 9N /
2014 rock crusher "GO tortoise GO!"
2016 Byrd Rooster
Father of the "11" time National champion,and worlds fastest woman ATV racer
A few fast LT80's
250R~300cc's
300ex
350 Rancher
Kymco Mongoose
Survivor of the 12 Hours of ATV America 04 and 05