Modifing port timing is the anser for changing the power levals 

using the milling machine is the only way to preform this opperation corectly

the port heights and corner radiues are all the same

which makes the motor run evenly on all the cylinders

which can not be done by hand also notice how wide the bridges are between the  ports there is .200 or 5 mm bridge with which wiil provide beter piston ring suport 

no cracked bridges like the 140 and 235 motors have problems with and you get more port area on top

                                                 you win.

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