5hp PROSTOCK Zenoah 4 Bolt 29.5cc Engine

PROSTOCK - An affordable/mild version of a full mod. The PROSTOCK's are rated at 5-5.5hp, full mod's 6-6.5hp, and full mod long rods 7-7.5hp. We guarantee performance of this engine to be as much if not more than similary priced ported engines. 

The PROSTOCK line has replaced the Race Ported line. The PROSTOCK engines produce more power than the race ports and are more economical.

To keep costs down, we focused our time tuning this engine to the areas that would yield the most power possible while maintaining reliability and ease of use. At OBR, we do not believe in stacking or using thick cylinder gaskets. We always machine and reshape the combustion chamber on our stroked engines. To help with reliability, we also relieve the piston. Piston reliefs help reduce the chances of the piston seizing on the exhaust side of the cylinder when running lean or hot. We were the first in this industry to do the piston relief several years ago.

Being that this line is a budget/starter engine, we tuned it to run well with any exhaust. We kept in mind that you may not have a pipe. We have seen great performance with everything from an HPI can exhaust to a pipe. If upgrading to a pipe, we recommend the Jetpro Boss. For those of you that are new to ported engines, we shot for ease of use. This engine is very easy to start and to tune the carb. 

We have left the porting open on this engine. At any time, you may send the engine in to us to be upgraded to a full mod or a full mod long rod.