I have a 2000 CR125 and it seems to have lost ALL low end power and no longer idles. I just bought the bike and the first day of riding it seemed okay to me(My first time on a bike), but my friend who has been riding for years said there seemed to be some bogging and noise from the engine. We got home and took of the cylinder and head. The Piston looked pretty new, but we replaced the ring and torqued everything back to spec. I then decided to bring it to a local mechanic to have the carb cleaned and adjusted. The mechanic did a few extras for me by taking the top end off and inspecting it. He ran a compression test and said the compression is great, and it has great spark. He also agreed the top end looked pretty new. Well I took the bike out for my second time ever and this time it wouldn't idle at all and had NO low end power. I changed the plug and still the same problem. The mechanic thinks it might be the crank and crank seals. Does this sound right? Any other ideas what this could be? Thanks in advance from a worried new rider.