If you increase the throttle trim on the TX it ceates a high idle until you hit the brakes The best place for the trim is nutral. Ajust the brake manually, and the throttle on the carb. Then you can use the trim to up the idle for startnig cold, and adjust the brakes when they start to fade with out . If your TX has end piont adjustments you can make the sevo push more or less, but I would adjust the brake so they work good with the trim 50/50 (0 thotle 0 brake). Then use the trim when you need it.