Hello 270,

your problem can be either thrust or rudder (or both...)

Have you trimmed your rudder first? Assuming this has been done (for full throttle condition), you can test your right thrust this way.

Do a vertical climb with full throttle and let the plane go. When it slows down (and not before), observe if it yaws left. If so, you need more right thrust.

Also, as Chipe Hyde suggest, right thrust can also be addressed by radio mixes.

Bye!