Hi Ian,
Yeah, mine will run idle Ok on a .35 pilot jet too, but at 1/2 throttle you'll be well into the needle jet range, so should concentrate your efforts here. Unfortunately this also is the hardest one to figure out, as there are so many permutations! Ask me how I know . . .
What size needle jet and needle are you using? Mine came with the standard 268k jet and a D27 needle. What colour is the plug? What happens if you raise or lower the needle a notch, better or worst? If it runs better without the air filter you are obviously way too rich like I was.
At this stage I found iit was really helpful to keep a detailed list of the settings and results. Only change one thing at a time or you'll be chasing your tail! Once you've found an improvement by changing a setting in one direction e.g. weaker/richer you need to figure out if you can move forward by just altering the needle position or whether you need to change the needle within the same jet or then change the jet size up or down.
If you change the jet size, I found you are often into having to find the correct needle that will now produce the same or better result in that new jet and so on . . .
Make sure you clean the plug thoroughly between settings and have a supply of new ones for when you start getting in the right ball park. It can all take a considerable amount of time, but you do get really quick at changing carb settings
![Very Happy :D](./images/smilies/icon_e_biggrin.gif)