carburetor adjustment

Ok so i have a mild built 212cc. Installed a 26mm mikuni with 130 main jet and 12.5 pilot. Ive kind of been going in circles with trying to tune it. What is a good needle setting and mixture screw setting to start with? Ive got it to run decent but it boggs after free rev and sonetimes backfires...

I installed a new carb on my doodlebug...set the idle to a decent rpm, screwed in the spring screw till it seated and backed it out 1 1/2 turns. The dang thing will not start. It ran up and down the street, conked out and I could not get it restarted. Is this a common problem? Did not adjust...