I just fired up the 125 trimoto. new mag side seal. would first pull no gas at all, looked at the needle and there was a groove were it sits on the seat. sanded it down, now it pulls fuel and loses then pulse. air bubbles are coming out of the carb inside the line, making it hard to pull gas. its the older 125 with no pump> gravity feed. I was running it on an aux bottle below the carb I don't think thats the issue. Any ideas.,?