I purchased one, ran it two weeks, could never get it to run right, (erratic idle/top end RPM, air bubbles sucked in from the RNV,...the usual stuff in the thread) sent it back to OS, got a brand new replacement under warrenty claim, took it out of the box and have the same problems. This one won't even run well enough to conduct break-in procedures. 2 for 2 in the bad column. I guess I will have to join the ranks of throwing OS's comeptitors stuff (K&B RNV, Perry carb, Super tiger parts) on this thing. I really dont feel like I need to keep paying postage to swap out a bad engine for a bad engine