Plugs

Well after running the Maxim for a week I changed the plugs and then colortuned and synced it today. Plugs are 1-4 L-R. FYI #3 unfortunately is due to petcock diaphram failure. Had ND(Nippon Denso) Plugs in it. Replaced them with NGK's.

 

I appologize for sounding a bit frank, but running rich on one cylinder or gas running out of the back of a carburetor is not the sign of a bad pet cock. The pet cock may be faulty, but it is more a sign of a bad/dirty/stuck float valve. The little vacuum diaphram is a great belt and suspenders solution to keep fuel from flowing while the engine is not running, but is just a cover-up when the float isn't working as it should. The net effect is that you are not able to maintain proper bowl fuel level since the float is no longer controlling the fuel level which will have an impact on the tuning of that individual carb.

I'd suggest a good cleaning of the bottem end at least, never hurts to clean the carbs (at least it doesn't hurt the carbs...).

The others look good from the grainy picture.

 

Carbs are clean. I pulled the vac line off of #3 intake when I removed the tank to work on it and fuel ran out of the vac line.