Help with "satan" my xj650 carbs too rich

Ok guys. So im still taming this b***h but getting closer to winning. Time for a bit of help please!

Ive set my coarse idle mix screws at 1.5 turns

If i start the bike she fires up, runs for a min and then chugs and dies from being too rich. Then ive gotta clean the carbon off the plugs n start again.
If i rev her up she runs good above 2000rpm.

This is is from cold and not using the choke, hence why im assuming a rich condition.

All four cylinders are similarly rich.

Any ideas why this would be happening?

I think my problem must be the enrichment or pilot circuits. Any ideas of where to look or how to rule out stuff would be greatly appreciated.


I think ill recheck float levels tomorrow, and the enrichment plungers, and the pilot air and fuel jets.

Hopefully the answers somewhere in there?

Hope you guys have some ideas....

 

you are not using the choke to start? why?
are you sure the choke plungers are fully closed (off)?
Have you tried readjusting the mixture screws to less than 1.5?
what year bike?
this link shows jet sizes, depending which 650 you have different jets could be you have the wrong ones for your year and model
http://xjbikes.wikidot.com/carb-specs

 

Had similar problem with a seca
Previous owner had drilled pilot jets to clean them @(&(&@(&!!
And bad diaphragms in 3 carbs

 

I don't know enough about an xj to be much help but are you putting the air box back on completely? My Honda would foul the plugs in minutes without the air box.

 

Xj550: not using choke because its too rich and starts without it at present.
Choke plungers appear closed but im checking them today.
Havent tried adjusting below 1.5 turns yet
The bike is a 1982 seca.
Will check jets today.

Toomanybikes: diaphrams are all new, checking jets today.

Stevem: airbox is on correctly.

 

I'm curious to see what jets you find, too....

Another possibility is:
Related to slide needle/tube....

Wrong slide needles and/or wrong positiob of clip/Worn slide needles/emulsion tubes, etc....

 

Look at your needle jets. The ones that the needle goes into to meter your main jet. If the hole is worn out by the needle, aka oblong. Worn out ones can cause a rich condition like what you are seeing.

Also, check fuel levels of the carbs. Excessively high levels can cause rich conditions as well.

 

Ok so tinkered today, wound the idle mix screws all the way in (soft seat)
Still runs rich and wont idle. Dies within 30 seconds.

Gunna pull the carbs n take a look tomorrow and inspect the shit outta everything.

 

The good news is that it seems to be a issue that is common to all 4 carbs. Since it runs with the pilots screws completely closed you are obviously getting a lot of fuel from somewhere else. The enrichment circuit is the first place I would look to make absolutely sure the plungers and seats are in good condition and that they are fully seating. If that's good then I would measure the jets and make sure that none have been drilled. Others have mentioned the setting of the slide needles, and condition of the emulsion tubes which should be checked. Don't know about your carbs but on the Hitachi carbs there are two jets under the diaphragms that can be switched and cause problems. I am also assuming that the carbs are getting enough air through the air filter. In fact, you might want to remove the air filter and see if that makes any noticeable difference. Be sure that the needle valves and seats are in good condition and completely seating so that fuel is not overflowing the bowls. Finally, confirm the float setting by wet checking the carbs several time before reinstalling them. After wet setting the carbs I leave them hooked up to the fuel for a couple of hours just to make sure none are overflowing over time. That's the way I was finally able to determine that I needed new needles and seats.