QUOTE(last337 @ Apr 29 2013, 06:39 PM)
I spoke to a guy at dirtyracingandrods and he seemed to think going from 115 to 150 was a pretty dramatic step especially if the car ran before. He was asking me to diagnose the progression and he seems to think I should only to a 120 first. CB has a chart that specifies 130 so I am not really sure what to do at this point.
Of course it runs. The idle circuit does all the work before you get about 2000-3000 R.P.M.s, and even 115s are supplying
some fuel. The only way you will know for sure that the jet sizes are the perfect for the given engine and ambient conditions is with a wideband air/fuel ratio gauge. Even then, they will change as conditions change. This is why drag racers change jetting throughout a weekend (and ostensibly why IDFs and Dellortos are made to facilitate easy jet changes).
It sounds like you're just trying to get the car to run better and get it in the "ball park." The ball park for you is dictated by the tables you have already read, which suggest for an aircooled engine, at your given displacement, somewhere between a 145-155 main. Keep in mind that a 2.0 flows very well compared to a 1.6, 1.7, etc., so those tables really are more of a sliding scale. Tomlinson dedicated a lot of time and energy to make sure his numbers were applicable for aircooled engines across the board, so I trust him (and much of this was before modern AFR gauges existed).
115 to 150 is a big jump, true. And just because it was true for Tomlinson means it will be true for you. The best you can do is take what has worked and start there. Again, Aircooled.net offers a jet exchange if you're not happy with them. John also has a lot of experience with these cars and might be able to give you his advice, which is far more expert than mine.
As an example though, my 1.7 had 115s and I jumped up to 135s and it still might really be better with 140s... but I like the fuel economy and I keep an eye on my head temperatures.