2005 Dyna 9000kms. Stage 1, carb.

I am starting to get a backfire out of exhaust on startup .. It will backfire when cold and fuel enricher is out. It will also backfire when engine is warm and the enricher is pushed in The bike runs nice and smooth when it is up and running. I have noticed the exhaust smells snd sets off my CO2 alarm in my garage. I am wondering if it is running a little rich and how to adjust the fuel/air mixture screw. eg.. how many turns from the seat postion.

 

If you have an aftermarket exhaust and stage 1 intake, turn the air mixture screw 2 1/2 turns from lightly seated. Don't roll the throttle before you start, that pumps extra gas in the cylinders before it starts.

 

and can also blow a head gasket