fueling problems

1985 xj700
I'm trying to diagnose an issue I'm having with an engine that I'm attempting to revive.
Here are the symptoms:
--engine will start and run well with little to no choke.
--after a minute or two the engine suddenly dies.
--wont start up again unless I leave it alone for 5 or so minutes.
--signs of life when it gets a hit of ether but wont start
--plugs look good

It seems as if the bike will run after the carb bowls fill, and it dies when fuel is depleted. I have a clear inline filter and I can see the fuel being suctioned into it. Any help would be greatly appreciated.

 

I should have mentioned, the carbs are swapped over from a running bike, so I am assuming that they shouldn't need much adjustment.

 

Stevo, the donor carbs have to be synced to your mill, also the symptoms you describe sounds like fuel starvation, float levels, petcock, filter.

 

The donor carbs came off another 85 xj700, does that matter?

 

Yes, the carbs are synced using the vacuum created by each individual cylinder.

 

I had a similar problem with a1982 750 SECA. Mine turned out to be the fuel vent in the gas cap was clogged. Try running bike with fuel cap open.

Good Luck...

 

I see Wizard...
Are the symptoms that I described indicative of out of sync carbs or would that manifest itself in some other way?(i.e. low power, backfire,etc.)
btw, I knew that at some point in my xj career I would have to learn the mechanics of carb syncing. So to the forums I go. Thanks
Oh, mcmeyer, none such luck. Gave it a try and the issues persist.Thanks for the suggestion.

 

My bike would die when throttle was applied.
After carb synch the bike takes all the throttle you want to give it.
This was after a carb cleaning which is equal to a carb swap.

 

Can't swap 'em between even two good-running bikes without a re-synch, trust me. The adjustment is too fine and minor variances in valve clearance, etc., between the two engines are enough to push it way off. I've tried it (knowing full well it probably would have the expected poor results) and it didn't work. But that doesn't sound like the root cause of your "running out of fuel" issue. Sounds like a plugged gas cap vent, really.

 

Carb synch is free. Do it.

Take off the tank and use a bottle.

Check float heights.