first as u begin to build your frame u want to make sure you have the best fitments as possible this bill help strengthen your motorcycle frame. ok let say you have every piece cut up to proper sizes as u begin to assemble this frame your going to tack it all together(this serve 2 purposes). to every tack you lay make sure you also tack in the opposite side( this is necessary to avoid any pulling/warping from the weld being layed down later )after the entire frame is completely tack check it for squareness in every possible direction specially your line of travel and your rear axle plates alignments , after u done all this and your satisfied with the frame go ahead and weld it .
NOTE: AS U WELD YOUR FRAME MAKE SURE NOT TO PUT TO MUCH HEAT IN ONE SINGLE AREA AT A TIME JUMP ARUOND WITH YOIUR WELDS