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525 engine thoughts


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I've seen a lot of posts about converting sx transmissions to 6 speeds but what are the possibilities of installing sx cranks and flywheels into exc or mxc cases? Not that I'm thinking about doing this to my new bike, but when rebuild time comes. A 41mm carb and big bore kit would be nice additions at that time too. Does the 570 kit require an aftermarket crank? Just thinking out loud here. ­čśó

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  • 7 months later...

Travis do you have any idea what the compression is of the piston kit you describe? Or if there is a 12.5:1 available for that size or the 540 for that matter? Also do you know if this works in conjunction with a cam modification like the hotcam? I remember reading somewhere somebody was unhappy with their big bore kit (can't remember exactly what it was) because it would not rev past a certain point. I'm pretty sure it was on ktmtalk but not positive.

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The compression for the 570 kit (99mm) is 11.5:1 There is no other piston avalible in the 99mm bore. For the 540 (97mm) ther are 2 compression ranges avalible 11:1 and 12.5:1.

The stock cam causes the motor to feel a little flat on top when used with the bigger pistons. The 8/06 cam is a good choice for the 570 or the 540 with stock compression.

The HotCam will really makes these kits scream up top end they will feel soft on the bottom. The Hot Cam is a better choice for a hi compression motor because the higher compression piston will offset the bottom end loss caused but the cam

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