Hey guys i was just wodering what the 505 big bore helps with on a yfz 450 and id it really has big performance improvements and also how reliable is it?

 

The 505 should add power everywhere. You really need to invest in a balanced crank if you want reliability. Big bores don't generally rev as readily as their stock bore counterparts, but the longer stroke should help add some torque and let you hold each gear longer.