912UL choke rough running

When I built my Highlander in 2006 I was having a hard time finding a good choke cable that would properly activate both chokes simultaneously. I settled for just activating one choke only on the theory that once one side started the other would be only microseconds away. My installation has worked perfectly for going on 14 years and 950hrs.

On another note, if you are experiencing the occasional pop it is unlikely to be excess fuel. That would cause "flooding". Pops are caused by short periods of leanness.

On a final note, once your engine starts turn off the choke; the only reason for a choke is to start a cold engine.

Alan

So this morning I tried the cold start with the choke. I shut the mags off whilst the engine was trying to commit suicide and sure enough the port side exhausts were cold whilst the starboard exhausts were hot. Seems that the issue is with the port carb. I removed and blew through the choke jet in both float bowls but these were clear as they were the first time I checked. There must be a blockage still internally in the carb so I'll have to strip it again. The air holes for the choke circuit are tiny so I can imagine it would not take much to block them.

Both chokes extend from stop to stop and mechanically operate evenly so it isn't an imbalance there.

I flew it all day and it runs great with all T's and p's normal and the running smooth. It's very cold though and needed starting with the choke twice having been left standing for a while. Both times a brief period of suicidal behaviour gave way to normal running when I shut the choke off. Again it wouldn't start without it when cold. 

At least I know which carb to focus on now. Thanks for everyone's comments.

Be sure to re-check the exhaust pipes where they connect to the muffler.

It is not uncommon for the joints that are held in place by the springs to jump out of position during a violent shaking event.