Do not use throttle to alter engine speed during several motor runs do so only by altering needle valve setting from rich to lean and back to rich. Allow it to run at lean settings for no more then 1-2 minutes each time. If you get it too lean you will notice an abrupt reduction in speed because it's overheating NG.After running on bench in this way you can continue the break in in the air but set it to barely lean then back off needle 1/4 turn. At this time you now may use throttle to control speed. Good flying, hope you have an instructer or don't try it. Get yourself someone to check plane out for trim etc.