your NEXTAR should have a already broken in engine from the factory, although the settings should be rich when you open the box if you let it idle to long like the posts have said it will load up. before take off straddle the fuse and run it up to full throttle to clean out the load up after a couple of flts. 3 to 5 tanks full, have a engine guy from your club lean out your motor a bit for max performance having a experienced club member help out saves you allot of time. after you see it for yourself it makes it a whole lot easier to do yourself knowing the right sound to listen to. like bruce88123 stated yours might be the one rich one but the basic break in should have been done before assembly.the rich settings are so you dont burn your new engine up in the beginning. you live in Ontario are you flying in cold conditions? if your fuel gets to cold it will thicken which can appear like you are running to rich also in northern cal its cold but not like Canada I store mine in the laundry room out of the way but warmer than a cement garage floor or shop. your engine warms up in about 30 seconds of running at full speed. good luck.