1983 XS 400 gas stops flowing, losses power

[chefsonly400]

Finally got my barn find on the road. Rode 2 miles and the lost power and the gas stoped flowing. Pulled over tried to start, saw that fuel was not passing through fliter.
Replaced a petcock (aftermarket) month ago due to leakage and the vacuum hose )1/4 inch fuek line) is new and longer then the original. It seemed like it was pinched going into petcock.. Removed, refitted vacuum tube... sprayed a little starting fluid and it started and fuel flowed. Rode 1 mile...same thing fuel stopped.
Any thoughts?

 

[amc49]

If you picked one of those smaller petcocks marked as not to be used over 350 cc. then that, the passages are too small. Vent open?

 

[Gra900]

I would check your fuel filler cap. Is it letting air in. I had the same, fuel hose empty, engine stopped. Opened cap an the fuel flowed. Good luck.
Post how you get on.

 

[amc49]

If OEM petcock then put it on 'pri' and run it there and see if it does it. If your engine vacuum is down the engine has better vacuum at lower rpm but it drops off at higher and the valve may be closing off. Why I defeat those every time I see one.

 

[chefsonly400]

Thank you for all the info. Looking into all the suggestions. I'll share what I find