Vento V Thunder Manual !!better!! -

A: The manual identifies two causes: 1) Leaking exhaust gasket (Replace the copper ring). 2) Lean pilot circuit (Turn air screw in 1/4 turn).

For every 1,500 meters above sea level, the manual suggests going 1 step leaner on the main jet (e.g., from 100 to 98). Vento V Thunder Manual

If you are looking for a service or owner's manual, you can find them on these platforms: A: The manual identifies two causes: 1) Leaking