HONDA GX390 / PREDATOR 420 HEAD/ DUROMAX 420,440/ LIFAN 420 PORTED, BRONZE GUIDES, POLISHED. Does not include valves. NEW PERFORMANCE CYLINDER HEAD. Fits : Predator 420 / GX390 / duromax 420,440 / lifan 420 and more of this style. Brand new and heavily modified cylinder head for racing applications. Cylinder head design allows the intake charge to get supercharged during valve overlap with proper cam selection/design and this head is the best at this. This makes modified head such a great tuning option. And the best head to run on the GX390/ 420 / 440 / 460 +. This creates the quench effect which is tight areas between the piston…