The Ever Infamous XJ 650 Carbs

So I bought a 1980 Maxim, when I purchased it, it started up fine, but when I drove it home I could tell it was bogging down until I hit a certain RPM. Took it home, changed the oil, changed the airfiler, tightened some stuff up... etc. It's been about 2 weeks since I initially drove it home. Now it will start up for about 20 seconds then die. Then it will turn over great, but just wont start.

Smells like its getting too much gas... any body have any idea what this could be. Is it just a carb adjustment or could this be something else. From my research I can see that I will have to do alot of work on the carbs so I'm no too scared of that... yet? Anyone know of a good walkthrough on the Forum? I'm new so I would appreciate any help.

This Forum Rocks!!!

 

There's this: http://www.xjbikes.com/Forums/viewtopic/t=2908.html

Also did you check your rear brakes for delamination?

 

Yeah, I checked the brakes. They were replaced fairly recently...

 

After you clean the carbs and everything, check your float levels using the clear tube method. If one of them is too low, it could be starving that cylinder for fuel once all the fuel in the bowl is used up, which would explain why it will only run for 20 seconds.

 

Anyone have a link to a good forum that describes how to use the clear tube method?

 

It sounds like you were not as thorough as need-be in doing the Carb Cleaning.

Remove Fuel Bowls
Floats
Valves
Jets
Clean Jets and Passages

Remove Top
Diaphragm Assy
Emulsion Tube
Clean Ports and Passages
Remove oxidation on Bore

Cleaning the Carbs correctly is a considerable amount of work.
Every detail ... especially Passages and the Pilot Air~Fuel Passages is vitally important to having the Carbs deliver Fuel properly and get Fine Tuned as needed.

 

When I bought the bike, the guys told me that he had just rebuilt the carbs... I believe that it is a sync job that needs to be done. Looking inside of them, the look quite clean

 

I don't know if there's a forum, but here's a pic of one user's setup:
http://xjbikes.com/coppermine/displayim ... os=12.html

Basically, you get a clear tube that fits snugly into the drain hole at the bottom of the carb bowls. With the petcock on "prime", open the drain screws, and fuel flows into the tube and equalizes at the same level as the fuel in the bowl. Look at the pic to see the fuel level; it's just short of the lip connecting the bowl to the rest of the carb.

I just used one tube and did each carb one at a time, instead of the picture which shows a tube for each carb.