Softstart Roughness

Have you checked your idle jet mixture is correctly set, 1.5 turns out,  from gently seated full in ???

This is quite a good instruction: https://electricmotorglider.com/wp-content/uploads/2017/04/CV-Carb-Part-3-web-1.pdf

Yep. 1.5 turns.

Hi Gil

Is this a new installation or a problem that just developed?  

Indeed the air gap of the trigger coils may affect the soft start, check the clearance of each trigger.  Be sure that both modules are the same part number, only some are soft start.  

Cheers

Great information. Thanks. It's a used 912 that I bought. Starts great, runs great, unless I connect the soft start. Once the soft start period is "over" (about 5 seconds or so) it then runs smooth again.

I don’t think the older 912/914 required the soft start modules. The higher compression 912s would benefit. Perhaps someone installed them and didn’t bother changing the flywheel as required.