sorry, i forget to mention that i only have 0.12 0.15 and 0.20 size. So i measure the exhaust with 0.15 and it feels little bit tight, then i adjust with 0.20 tight also so i think everything is OK
thnx

oh one question more... new drive sprocket... i take old sprocket too fast out to remember witch side goes where..... extended part faces outside or to the motor?

Sorry about bad English..