Hello! So I picked up a 2003 XR100 and can't get it to run.. we've tried to clean the carb, replaced the carb, new spark plug, air filter, adjusted the rocker clearances on the valves, checked the timing, and kind of out of options at this point. It has spark, but also has little compression (I dont have a compression/leakdown tester, but can pull the starter down with a finger or two) - some kicks have compression, some dont. I've talked it over with a few people and they suggest a potential top end rebuild, or it might be cheaper to replace the motor. What will I need, and what will it cost? Thanks!