Bike running rich

I am still having problems with my SECA 550 running rich. I cleaned the carbs completely. I set my valve clearances they are correct. I have adjusted the fuel mixture screws in to 1.5 turns out. I bench synced the carbs using the paperclip method suggested here. It was still running rich. I had wet set my floats so I lowered them some more thinking that they may be set too high and have too much gas. However after doing that the bike runs lean when I apply throttle. That is I get some back firing etc, and it does not have the power when I get above 4500 rpms. I think I have the gas too low in the bowls now and I will readjust it. Could the enrichment circuit be leaking and how would I fix it. The bike starts right up as without any choke but it will quickly foul the plugs at idle. Any ideas. I know that I need to sync the carbs while they are running but I don't think that is really possible until I can get it to idle without fouling the plugs. What else am I missing.

 

When you cleaned the carbs did you happen to check the jet sizes?

 

Put the float levels IN SPEC don't try to use tweaking float levels to compensate for something else.

Pilot screws should be at 2.5 ~ 3 turns out.

You'll get a much more accurate bench sync using the relationship of the butterflies to those tiny holes in the top of the carb throat.

The first thing to check in regard to the enrichment plungers is that they are all FREE when the "choke" is off. Make sure that when off, there's no lifting going on with any one of them.

The other thing to check are the rubber seals inside the bottom of each enrichment plunger; and the "seat" where they seal against. It's not uncommon for the seats to be pitted or the rubber seals damaged or flat gone.

Another possibility for Mikunis inexplicably running rich or dumping fuel is the o-ring on the outside of the needle valve seat. If that o-ring is gone, fuel will leak right past the valve seat even if the float is doing its job.

 

You say the pilot screws should be 2.5 to 3 turns out. If I turned them in wouldn't that make it run leaner and let less gas in at idle? I think that I will just replace the O rings on the pilot screws and the plastic washers on the enrichment circuit to eliminate those as a cause.

 

Yes, you should be horribly lean where you had them set meaning the problem is likely coming from somewhere else.