Review on 🏎️ Ultimate Performance: Black High Compression Racing Head for 2 Stroke Engine Kit 66cc/80cc Gas Motorized Bicycle by William Hood

For less than $30 (what I bought it for) it's worth it. To be honest, it hardly (if so) increases compression enough to be noticeable when riding a Chinese motorized bike. The real value of this head is that it dissipates heat much better than a stock head, allowing for cooler engine temperatures for a better ride. If you really want to increase your compression ratio, invest in a copper head gasket. If you're tight on cash and want to boost the performance of your 66cc engine, start by fiddling with the exhaust and intake. You get much better performance results than buying a CNC head. A NOTICE. The engine head offers better compression for two reasons: sealing between the engine and head and changing pocket geometry (where gas and air is compressed before being burned). The new head is CNC machined at the contact point, your Chinese motor is not as accurate. So get a CNC head AND a better shim than the stock crap (even a shim maker is better) then you will feel the results.