Here's a web site that explains in depth how to initially setup and adjust Saito engines. Even though you do not have a Saito there are enough similarities that this site should be some help to you. It has helped me understand the proper setup of my Saito as well as a couple other non Saito engines. Also, make sure you have a good quality 4 stroke glow plug. OS makes reliable ones, so does Fox. If you don't have a fourstroke plug the engine will not run worth a darn and you will be wasting your time. If you don't know what you have go buy a 4 stroke plug before you go any further. I have a couple Magnum 4 strokes and they will run well but like any four stroke you have to learn the basics which the site I am posting will help you with.

http://saito-engines.info/throttle_setup.html