I had a problem this race weekend that is baffling me. My normal procedure at the end of race day is to empty the gas tank and fuel line. Race day I fill the tank and purge the line till it is free or air. First practice it ran fine for 8 laps or so then I started getting a brief lag like I was running out of fuel. Returning to the pits I noticed about 1/3 of the line had air in it (nearest the tank).
I cleared the line again and returned to the track and the same situation occurred. About 8 laps in I would get a brief lag. Back in the pits I noticed the same issue with air in the fuel line. I replaced the fuel line thinking maybe a small hole. First qualifier I had the same issue with stuttering lag about 8 laps in. This time I clamped the ends of the in tank fuel line with safety wire.
Next qualifier the same issue. For the final it was suggested to try a fuel filter at the low point in the line to act like a reservoir and while that did take care of the stutter / lag I still had air in the line as before. The tank is new (3rd race) and the only thing that was changed between last race and this race was I replaced the diagram only on the carb (KA100).
I’ve never had this issue before, but in talking to other racers some have this issue but never to the extent that it causes performance issues. Any ideas?