6274 - 7.5hp CNC Ported Full Mod Zenoah 30.5cc 4 Bolt Engine

This engine now comes with a TR/OBR billet crankcase at no extra cost.Every long block or engine is now CNC ported and hand finished. CNC porting and hand finishing is all done in-house by the OBR staff. We do not contract out any of our porting so every engine is modified to our exact specifications. We are able to offer higher accuracy this way as well as more power. Our CNC machine has allowed us to take our porting to the next level due to us being able to do cylinder work that is not possible to do by hand. The full mod 30.5cc has proven to be one of the most popular engines we build. With the higher reliability of the 4 bolt Zenoah engines we were able to achieve more power with out sacrificing reliability. We put all of the knowledge that we have picked up from years of dyno and field testing and came up with a monster. To start we completely tear down the engines and perform the following modifications: 1. Machine combustion chamber for a proper squish clearance without stackin