Throttle Curves

Maybe I am missing or overlooked something with the throttle on the Pepsi Chipmunk. At present the slightest move up from low and it's power jumps up quite significantly which means on landing it can be a bit interesting as the slightest move of the stick and it's going to start flying again. Originally I had copied the curve values from Pennzoil which flies just great. The engine and throttle linkage are identical and the run-times so far are negligible, yet so much difference? The only difference that may have a factor is the prop which is Menz 18x10 compared to Pennzoil which is Menz 18x8.

I have really flattened the curve which has given a better linear feel to my stick but the low throttle is still quite lively.

Thinking maybe move servo arm linkage a hole inwards, therefore reducing the throw. Any suggestions from you more experienced aero gas, sorry, petrol engine users?

Are you using most of the servo travel? If you've clipped the end points (a lot) in your transmitter you will have lost some of the resolution of the servo.
Is the carb moving freely? If it catches and jumps suddenly, you will have the effect you describe.
Flatten the curve even more to give the desired effect. I assume you have a multipoint curve so that you can have the desired response at the top end as well as the bottom?
Swap props and see what effect it has.

Just a few ideas to play with

You may also wish to review the servo linkage to make sure the wrong mechanical exponential has not been built in.

A bit of job accessing the throttle servo as it under the battery tray. Watched the servo HS255MG and it is rather difficult to see if the arm gradually increases as the stick is moved upwards. Maybe it has a bit of a resolution issue? Swap it out for a Spektrum 5030. Awful servo. Even their bigger brothers made an awful noise especially with the slightest loading. Anyway, fired up and appeared to a bit better but the engine rpm did not seem to return where I had set it although it gave a more progressive feel.

Took it out again and fitted another new HS255MG Mighty Mini (so quiet) and and reset throttle trims and adjusted linkage accordingly. Will see what happens tomorrow after another start up. So strange this issue because the same identical set up is in Pennzoil.

Fog sort of lifted but still damp but went outside anyway with Pepsi. Throttle appears to much much better now. It must have been that damn servo. Although Pepsi has been naughty - ruddy prop bit my hand on kickback. Lucky I had a leather glove on although I have got blue/purple nails now. Can't remember what words I said but one of them was - Ow!