XJ700 stalled on highway at 60 mph/5000 rpm - fuel flow?

Took the XJ out on the highway for the first time. She hits about 5000 rpm at 60 mph. After about a minute or two nothing woulf happen if I kicked the throttle more, put she would stay running at around 55 mph. When I extied the highway and dropped the throttle she stalled. I pulled over and after a minute or two I saw the fuel filter was almost empty. It slowly filled to about a quarter (normal level since it is on an angle) and then she started. Made it home fine in stop and go traffic. I checked the vacuum line from cylinder 2 that should boost fuel flow based on rpms. Everything looks good. Any way to increase fuel flow? Should I ditch the filter? Where would I be able to order a new diaphram for the petcock?

 

Fuel filters shouldn't have any bubbles in them that impede flow. Bubbles should be very small. You've got a bubble so large that it keeps fuel out of the inlet and/or outlet, but due to the diameter of the inlet and the surface tension of the fuel, the bubble can't get out, and fuel can't flow in.

What kind of filter is it and how is it routed? I had one with a 90-degree bend, and could never get it to work. I could actually feel it get leaner as it starved of gas until I replaced it with a straight through filter.

 

I wound up putting my fuel filter so it was vertical, between the 2 & 3 carb boots. It's not as easy to check or change, but it stays full of fuel. I had the same issue of the filter not filling up when it was horizontal- if I was lucky, it would fill even with the bottom of the hose fittings.

You can get a new diaphragm from chacal/XJ4Ever, or from any MC shop. I paid ~$25 for my K&L petcock rebuild kit.

 

Oh man! This same thing happened to me today! I was just about to get off the highway after going about 65-70 mph. Then I noticed it had died. Pushed her over off the road and it seemed as the fuel filter was close to empty. I tapped it a little bit and switched the petcock to PRI. Tried to start it a few times and then it started. Seems to be running fine now but the filter still looks low on gas. I should still have about gallon left in the tank.

 

Sounds like I need to drop the filter lower. Mine is almost horizontal. Too much fuel line in between. Thanks guys.

 

Twice I have seen some of these small fuel filters with too little flow capacity to feed the bike.
The littlest one is not always the best. Some of the porous brass things are impossible to get fuel through. They are made to go on a 5 hp lawnmower not a 60 hp bike so beware of what you have on it.

It's also possible that the filter did it's job and stopped a bunch of crud from getting into your carbs and it got plugged up in the process.

Tell tale sign>> Disconnect the carb side hose and put the petcock on prime. If the fuel POURS out, the filter is good. If it just trickles....well you know what you gotta do.

 

Got it fixed. Took out the fuel filter and made sure the fuell flows down directly into the carbs. Now no more issues.