4-stroke jetting basics

[dgsmooth]

howdy all - i just got a 2003 scrambler 500, just going through it and wantto make sure its running as good as it can be. it seems to run ok but seems a little low on power and back-fires bit... it has a white bros slip on on it, and it will have a better filter right away. i guess i'm wondering if the jetting should be stock with only a slip on and filter, or should jets and needle all be a little richer? how do i know when i have it perfect?

[polman500]

You'll probably need to be a little richer. You have to read the spark plug through trial and error testing. Make sure to start with a fresh/new plug. There is plenty of info on reading plugs available with a Google search and I think there may be a sticky post on this forum you can pull up with a search.