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TB 30/23.5 race head for 125/140

5.5K views 62 replies 14 participants last post by  burch753  
#1 ·
anyone run this new head yet? any details aside from the bigger valves, like ports, etc?



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#20 ·
the reason why your 146 felt better is because the low duration of the cam. the tb300 cam only has 230 degree of duration, once you throw the 160 in the equation the engine runs out of air much sooner, making the engine feel lazy. throw the r20 takegawa cam in and hang on. the r20 has about 250 degree of duration. i was able to turn 13k rpms out of my old 146cc with r20 cam.