Are there any people on the site that are familiar with the kaw 23hp to 25hp upgrade. From all the research I have done what I have found is that you should add the oil cooler, other than that, you can modify the throttle blade shaft stop to allow the butter flys to open further. What else I have read is that they are identical motors and carbs minus the shaft. I have a manual and it shows that the FH601,FH641,FH680 and FH721v should all have a 136 and 140 main if your at 0-3000ft elevation. My FH680 has a 104 and a 106 which is what I find on the microfish online, so this does not align with the manual I have. If there is someone familiar I have further questions on jetting, govner adjustments etc.
