6331 - Full Mod / Signature Series Twin Top Ends 57CC & 61CC Intake and exhaust ports are

Intake and exhaust ports are modified to our specs as well as the durations

46/47cc reed engine for the Primal MT

Modify intake port for better flow

This allows for tighter tolerances and higher reliability when a good sealant such as Yamabond is used

6331 - Full Mod / Signature Series Twin Top Ends 57CC & 61CC Intake and exhaust ports areReplacement full mod or signature series twin top end set. These top ends have been machined for twin use and our billet heat sink. Full mod is our production CNC porting and will have good power from torque through top rpm's. The signature series are ported more aggressively and will have quite a bit more power than the full mod version. We also offer custom tuning on any signature series top ends engines upon request at no additional charge. If