[Skools Out]

if it is like that the motor won't run if you reuse that sleeve, that sets to lower end timing on a piston port Kaw motor. i have ground them before to adjust the timing for different HP curve, you could do that but it's a ton of machine work and requires different piston timings as well. my old JS440 i have done all that to, it took about a yr to get it rebuild with all the timing working, but it's now bored to a 575 plus the compression will change alot doing that mine went from factory 90 psi to now 225 psi which then requires the crank plates to be welded or it will twist the crank. i would have the crank welded either way, if you raise the compression alot you'll need a goki hp starter to turn it over. i changed the head on mine as well which you should do while it's apart find either a Westcoast or PJS or JetSport HP head. if you do all that you will have to convert to the twin carb setup from JetSport perf parts. that's what i had to do, i went from a single 38mm carb to twin 46 mm carbs now but if you do that it requires the exhaust timing to be fixed and you must run the PJS twin 6 inch exhaust which is what mine now has. but they will fly if you do all this. mine went from a factory WOT @ 9k rpm @ 24 mph to now WOT @ 19k rpm and 87 mph, the coast gaurd clocked me whoops in a no wake zone 2 summers ago. your best plan is look on ebay and buy a used but good set of 750 juggs with some good pistons, i do have 40 or 50 sets of kaw pistons if you know what MM your bore is let me know i may have a set. as for the head change if you only change to an aftermarket head no twin carb change required, if ya need something let me know.