My 1982 CB750C wont idle right.I recently accquired it and I know nothing about the style of carbs it uses(and little about others).If I adjust the fast idle up to where it idles smooth it will climb to about 2500 RPM within 30 seconds or so,then I adjust it down to a good idle and it will die in about the same time.It also pops through the left inner cyinder.Any ideas what might be wrong?