有一邢台产拖拉机（195型发动机），在气温约20℃时必须借助起动液才能起动。是何原因引起发动机不好起动呢？摇转曲轴发现压缩力较小，排气门有明显的漏气声，喷油器可听到清脆的喷油声。据此，故障可能出在压缩系统。因此将气门罩盖拆下，发现整个气门室被烟熏得漆黑，排气门 A Xingtai tractor (195 engine), the temperature of about 20 ℃ must be activated with starter fluid to start. What causes the engine does not start well? Swing crankshaft found compression is small, the exhaust valve has obvious leakage sound, the injector can hear the crisp sound of injection. Accordingly, the failure may be in the compression system. So remove the valve cover and found that the entire valve chamber was smoked dark, exhaust valve