1980 XJ650G Maxim #2 Cylinder Running Rich

Been off this bike for a while. Had some problems with it running rich on 3 cylinders so just got through removing and cleaning the carbs, wet set floats and synched the carbs. Set pilots at 1-3/4 turns out. Still have to play with choke and throttle a little to keep it running until it gets warm. Runs good after getting warm except #2 cylinder is still running rich and fouling plug. I checked choke valves and they are all bottoming out when choke is off. I could adjust the pilot screw in another 1/4 to 1/2 turn. Any ideas on any other adjustments that might solve the problem?

 

so your mixture screws have the course thread? otherwise setting would be 2-1/2 turns from soft bottom
are the main jet washers flat if they are cupped it may allow extra fuel past jets.
keeping choke on untill warm is normal leave it on untill rpms start to climb then ease it back a little you should not have to touch throttle at all to start or keep bike running if all the jets are passages are cleaned.
have you synced the carbs yet?
when you say Set pilots at 1-3/4 turns out. you are talking about the mixture screw correct not the jet?

are you sure all cylinders are firing? any pipes staying colder than the others?

 

did you ever resolve this
Coils checked: 1&4 Pri = 2.7 ohms Sec = 12.02k ohms
2&3 Pri = 2.7 ohms Sec = 11.87k ohms

Plug caps tested between wire post and spark plug conn: #1 = 4.63k ohms, #2 = 5.26k ohms, #3 = 5.29k ohms, #4 = 7.08k ohms (a little high).

specs
pickups
1980-81 XJ650 Maxim and Midnight Maxim: 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range

Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug

 

your ignition coils are on the high side for the primarys this could be reducing your spark output voltage, and the XJ is a weak spark to start with. what are you doing with fouled plugs replacing or cleaning?

 

Thanks XJ550!
Mixture threads appear to be course, had them two turns out but changed due to rough idle and all cylinders seemed to be running rich.

Main jet washers may have been slightly cupped but tightened the jets down pretty snug.

It starts and runs at full choke for first minute or two then starts to sputter. I back off the choke some and then use throttle. It tends to die without keeping the RPMs up with the throttle until it warms up a bit. All jet passages were checked and clean when carbs put back on bike.

I wet set floats before putting carbs back on bike. Thought I had a float problem on #3 carb but couldn't find any leaks (a little wet spot seemed to keep showing up on that float while I had them out but think it was from fuel around the metal bracket between the two floats) Carbs were just synched after being put back on bike.

Pilot mixture screws right next to choke valve on top of carb. Put new o-rings on these screws before putting them back in.

All cylinders are firing. Just #2 spark plug keeps getting a lot of soot. Plug is dry and not wet after running just a lot of soot.

Haven't messed with coils after initial problems. Found that the end of the wires where they twist into cap had corroded and were real loose so cut about 1/2" off wire and screwed back into caps. Caps have a little auger like pin that screws into wire. Wouldn't hardly run until I did that. Have not tested resistance since then.

Plugs are fairly new so cleaning and re-installing existing plugs. I'm going to rotate plugs to see if it could be a plug problem.

 

with the mixture screw you put the spring on it then flat washer and o ring last? just checking.
moving plugs is a good test

 

Yes, spring then washer, then o-ring on bottom. Wondered for a while if I had the sequence right but it didn't make sense any other way.
Gonna check plug gaps and swap around this weekend and see what happens.

I'm in the process of rebuilding an 86 Yamaha outboard so kinda splitting my time between the two. You don't have a source for old Yamaha outboard throttle and shift cables do you? These have a screwball plastic shroud molded on the engine end that broke and can't be replaced. These are listed as no longer available.