what is the best way to have the correct spacing on pinion gear and center spur gear

close enough to run a pice of paper thru without tearing it is what i was always told i just go by feel and it has worked for me for years

Did the paper routine myslef for years. Now I do it by eye and feel.

so put paper in bettween gear and move spur gear with finger if it tears its to close and if it dosent its correct?

yepper that should be about right also listen it while running should be a clean wine if it is to tight will sound real rough almost like crunching and also you shouldn't be able to hold the spur and move the pinion/clutchbell with more then a hair of play