First off, this forum has been really helpfull, and especially the write-up on this topic. Everything went well, but I notice when I first start it the chain rattles until oil pressure builds. I made sure my oil filter has a check valve, and all the parts where done right. I always assumed an oil pump either worked, or didn't. Is there any suggestions on what to try? The motor was built in mexico, or atleast this is what is says on the oil pump.