Duromax Engine Compatibility

We get frequent calls about the compatibility of Duromax engines with our 420cc engine kits. 

Duromax sells a 420cc, 439cc and a 500c single cylinder engine.

We have tested both the 420cc and the 439cc and they are 95% compatible with our 420cc engine kits (NOT OUR 459cc). The ONLY modification you will need to make is to grind or shave down a very small amount of metal on the exhaust flange (1/16") in order for the exhaust to fit correctly.

The 500cc has a significantly different exhaust port and will require significant exhaust modifications. However, everything else with the kit will fit fine.