All cylinder porting is designed to suit application be it road race or motocross for example and to suit customer/riders needs/styles also by the limitations set by the manufactures eg piston rings gearbox ratios crank and bearings.
Porting work Prices start from as little as £60 for mild road porting on single cylinders
Just a couple of Samples, 1st one Honda RS125 NX5
HONDA RS125 NF4
Puch Maxi Before Porting and Machining
Puch Maxi after
These Modifications more than Doubled the hp
1976 KTM 250 Grass track porting
BMB 125 Kart tuning and rebuilding
CRANKCASE FLOWING MATCHING AND EPOXY FILLING IN SOME CASES
BMB CASES
HONDA RS 125 NF4
HONDA RS125 NX5
YAMAHA TZ250B 1991 
Yamaha TY250 porting and Piston Modification
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