A true high performance plug for an actual increase in performance. Rarely would we claim that a spark plug will increase performance, but we know if the original plug is defective, getting a proper plug will of course help. The NGK BP5HS goes a step beyond that, with an extended tip, it centers the spark in the combustion chamber and actually displaces volume, effectively increasing compression ratio. An added benefit is with the protruding electrode the plug is even more foul proof than the standard B5HS. Also, the 5 is a hotter heat range plug for those colder days. A really great spark plug for your modified 67cc engine.
Note: This plug may not be for all engines. It has not been evaluated in all engines. It may cause piston contact in 49cc engines and others. If you have removed head or cylinder sealing surface material or use no or a thin head gasket there may be piston contact. The purchaser is responsible for evaluation of this plug prior to purchase.