914 rough running at low revs

Check the bowls and low speed jets for dirt and corrosion. Actually take the low speed jet out and inspect, it has small holes in the side of it. And make the carbs are balanced.

make sure the carb throttle stop and lever brackets are not bent, the HK36 has a lot of leverage on the cables.

if it is bent, straighten them out and then adjust the throttle cables so the cockpit control hits the end of the slot slightly after the carb leaver hits the idle stop screw. This prevents the pilot from bending the bracket.

and then make the fine adjustments with a pneumatic carb sync. Be fussy that the sync is good, even when you pull hard on the throttle control. After a little “bounce” it should hit the cockpit stop and not be bending the stop screw bracket.

Problem solved, it turns out to have been a broken circlip at the bottom of the main jet, replaced both the circlip and the related o-ring, engine now runs as smooth as anything