First thing to do is make sure your throttle trim on your tx is in center position. How is your Throttle rod attached to your servo? If it is with a t-clevis then loosen the t-clevis open your throttle to full open on tx and manually open carb to full open. You should then tighten the t-clevis with the carb full open. Try this and see it it works for you. I have a chapman same size with a 91 magnum and that was the way I got it to work with a little trimming on throttle. I had to use a throttle cable instead of a solid rod but the principal is the same. J D