Help with stumble

[rustybronco]

If it smells rich, it's rich.

did someone mess with the jets that you may not know about(p.o.?), i.e. drill, change/swap?

make 4 adapters that thread into the carb drains, attach some clear tubing to them and run it up the side of each bowl. then check the fuel levels.

I checked out the spark plugs and they appear as follows: #1 is black and sooty, #2 looks rich (possible leaky petcock), #3 and #4 look perfect.

is the exhaust the same both sides with no crushed pipes, baffles missing, holes drilled?

replace the spark plugs for cylinders 1 &2.

3&4 plugs too lean? post up pictures please.

 

[JTsGS650]

Stock jets in the carbs. When I cleaned the carbs it looked like someone had been in there before since there are a few scratches etc. But the jets looked undisturbed and original. Exhaust is in really good shape with no dents. The only thing I did not verify is the position of the jet needles since I didn't have a pair of snap ring pliers.

After riding the bike in to work this morning, I can say for sure that there is a difference. The stumble is still there but it is better after raising the floats 0.5mm. I'll check the condition of the plugs again and try to get a pic of the plugs up.

I have also been meaning to pick up one of the Suzuki fuel level gauges to check the fuel level in the carbs. Seems like there's never enough time to work on a motorcycle.

 

[JTsGS650]

Better! and a few ?s

Better! and a few ?s

Been a while. I finally found time to pull the carbs off again. I raised the floats a full 1mm to 23.4mm set the air screws to 2 turns out and the stumble is all but GONE. It is still there but only ever-so-slightly only when fully warmed up.

I talked to a guy at the local 'Zuk dealership about this issue and he said that it may be "heavy floats". Meaning that the floats had absorbed some of the gas over time and that they would be heavier than they used to be which caused them to not float as well, causing the rich condition. It seems logical (I think?) and would explain why I'm rich on the cylinders in the left side of the bike and good on the right side since the bike was parked on the side stand for a few years with gas in the carbs. What do you guys think?

I also noticed that the pilot air jets in the carbs were 150s and my suzuki manual said that they were supposed to be 160s. What effect would this have on driveability. Is this part of my problem? TIA