The stock 390 with unlimited coil and MM I had ran around 14,100 and still four stroked plenty. Every saw is different, I've seen things at the other end of the pendulum as well.where did you ever see a stock 390 that 4 stroked at 13.5? lol was the one you had the only one you had experience with? 13.5 is what i tune stock 390's at and none of them 4 stroke warm. ya hear them buzz a little bit cold lol to run one at 13.8 is about the max healthy tune you will get away with without any upper transfer work and even then you need your other work done right. most guys doing there first port job won't know where to go to make them do those RPM happily and end up just making a stronger saw that doesn't do anymore RPM's then stock which is fine. if you port them a certain way the bottom ends run alot wetter so they are more up the the task of managing the higher RPM.
now this saw is rich lol
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