z400 motor problems

[z400suzuki]

hi, i got a problem with my 04 z400, started to make a squeal sounded like the top end of motor then shut down, started right back up and died again, and continues to do the same thing, just changed oil and is at the proper level coolant level is fine so i don't believe its overheating, took the valve cover off cam timing is good and timing chain is tight, also did a cylinder leak down test and passed with flying colors any help would be great, thanks

[z400suzuki]

update, started right up this morning and let it run for about 5 mins then locked up again, tryed to start it and was very slow to crank, waited a couple mins then started again, im guessing once its at operating temp maybe the piston or the rings expand to much? im assuming an over haul is in order but i was just wondering if anyone else has run into this problem and if so what there fix was any help would be greatly appreciated thanks