1 dark brown spark plug #1 cylinder

hi i have 82 xj650 maxim #1 cylinder plug is dark brown the other 3 plugs look cocoa brown on only half the insulator tip on all 3 plugs im assuming the 3 cocoa plugs are burning good, any ideas what could be wrong with #1 carb the bike seems to be running ok at idle and moderate speeds when i try to give the bike alot of throttle at around 55 mph it seems to have a hesitation or osilation unless slight amount choke is added then it runs great any ideas where the problem could be i have had all 4 carbs off cleaned them

 

I would say # 1 is a little rich, turn the air scew in the slightest little bit, ride for a while and check again

 

where is the air mixture screw they got everything packed in so tight its hard to see

 

This is probably not a "turn one screw" situation.

While you might get lucky; you have a carburetion problem of some sort.

If you start turning screws and tweaking without solid methodology you are going to make it worse not better.

"had the carbs off and cleaned them." To what extent?

Did you verify your float levels while the rack was off, using the clear tube method with liquid?

Were they then bench-sync'ed before being returned to the bike?

Have you checked/adjusted your valve clearances?

Short cuts won't work, trust me. How many miles on the bike?

 

the bike has 4000 miles on it i took the carb rack off the bike cleaned enrichment circuit ,pilots and main jets along with main jet tubes that the needles runs through as far as setting the float levels no i havent messed with them i figured they were set to specific specs so i did not want to disturb them plus im not sure how to set them ,and as far as valves i have not checked anything in that area the valves are very quite no noise coming from them

 

Good so far, however:

Valves get tighter as they wear, not looser. The original valve clearance check was due at 3000 miles, you are overdue; do not neglect it. ESPECIALLY since they have probably never been touched, they are most likely in need. Happy valves are slightly noisy, quiet valves are not a good sign.

Setting the floats correctly involves attaching a piece of clear tubing to the fuel drain to see where the level of fuel in bowls really is. The spec allows only 3mm "range" and this adjustment is critical to proper carburetor operation. This is most easily performed with the rack off the bike (since disassembly would be required to adjust anyway.) Do a forum search, RickCoMatic has posted a very nice color-coded diagram showing fuel level on the Hitachis on more than one occasion.