Idle Issue

The throttle lever spring is set up to pull the throttle to full open if the throttle cable breaks or slips.  The spring is really STRONG.  I couldn;t get a friction lock throttle cable to work:  if I let go of the throttle lever, the idle would creep to 3000 rpm +.  I've switched to lighter springs, but still have to tighten the throttle cable knurled knob as tight as I can to hole idle below 2000 rpm.

Michael, just as a test, I'd suggest disconnecting the throttle (not the "choke") springs and see if you can hold a more reasonable idle rpm.

Those springs do need to be disconnected before the mechanical sync...

Michael,

On your first start did the engine accelerate above 2,500 rpm?  If so how high did it go? How many times have you started that engine and it accelerated immediately above 2,500 rpm?

Vans RV12 had the throttle creep issue. Most just went to a better model throttle from McFarland Mfg. and a lighter spring. Using an inexpensive throttle isn't always the best choice. Many throttle's have a way to increase friction and sometimes that helps.

I had a Rotax A&P adjust the carbs, but they are still not completely synced.  The choke is sticking too.  Put on the new choke springs (from Rotax) and one choke still sticks.  After Christmas, I will have the A&P do a re-adjustment.

The RPMs issue has been since day one and usually above 4000 rpms, but that has been resolved . . . but both carbs still need adjustment.