Re: New engine worries ( 1st build)
Regarding oil mixture making it rich or lean:
If you add more oil, that oil displaces the gas, resulting in a mixture that has less gas available to burn and more wasted oil. If you add less oil, it will leave you with more gas and a richer mixture. If you have 16:1, 16 parts of that are fuel. If you have 32:1, 32 parts of that are fuel meaning it's going to act richer. I found it hard to believe when I first heard it, but it does affect how lean or rich your bike runs.
Yes, I have a 68 jet, and I am running an NT carb. You may want to try getting a smaller jet in the future, however, I'm now wondering if you have an air leak that shows up once your engine gets warm. Does your choke lever make a difference? When I had an idle problem, I either had to turn down the idle so far that it wanted to die, or the engine would want to rev up high and not come back down. The common places to check are where the carb attaches to the intake, and the crank seals. Try spraying those areas with brake cleaner; if it revs up when you spray it, it probably has a leak.