Setting my co2

Just adjusted my idle to about 850-900 and need to set my co2 reading as it running rich. Iv just bought a gunsons gas tester. Any help would be great I calibrate Machine to 2.0 then what do I need to adjust to whats the best setting it's a 1.8gti

they seem to run best around about 1.5%-2%. I found my gunsen tester was a load of parp, hopefully you'll have better luck than I did

All the info and setting is in a Haynes manual. I used a Gunson gas tester and found it worked alright as it was giving me the same reading as the MOT test and they use much more expensive equipment to get there readings.

I don't have my mk1 Haynes to hand but looked at a MK2 golf manual and the K-jet setting is 0.5% - 1.5%………?