Greetings all! I am new to the forum, and this is my first post, so apoppgies if I miss any protocol issues.
I ride a 2000 Sportster XLH that has been modified to a 1200. The problem I am having is when I get to speeds above 50 MPH, the throttle suddenly starts to cut out, and the bome spits and sputters, and tries to stall. If I feather the throttle, it will attempt to recover, but to no avail. Any help on this would be greatly appreciated, as I have already spent over $500 in the past 2 years to try and fix this very issue.

 

Sounds like a fuel filter is plugged, or a fuel line.

 

Does a Sportser have a vacuum operated petcock?
If so toss it for a real one.
Next like said pull the line from the carb and see if it flows freely
Of course, it will not with a vac , petcock.
But you have to eliminate step by step.

 

Sounds to me like the carb is too big for the build.

 

Sounds to me like it's more of a fuel supply problem than a carb issue. The above advise about the petcock and fuel flow is where I would start.

 

What has been done in attempts to repair it?

 

There was a bulletin at one time that on 1200 XL's, the vacuum petcock was to be replaced as it would create bowl starvation at higher speed(s).
Scott