Cheers guys, using the two out of one throttle made for rotax from aircraft spruce they are great for keeping equal movement however as you all mentioned the carby balance, I remember removing one of the carby throttle springs to reduce the full power pull on the throttle and checking this while stopped in different throttle settings found to be equal , maybe not while running so will replace the spring and test.
Also the mag test on the Savannah 912 at all revs shows no difference, but this one does only as I mentioned at under 3000 rpm maybe a newer electrical format in the ignition system but seems strange!
Cheers