Hey guys... I currently have an 05 CRF250R and am looking to add a 2007 YZ450F to my stable (getting a killer deal on one) Questions: 1) Are the top ends of the YZ450F's as easy to rebuild as the CRF's? I have done a few top ends on the CRF and re-ringed it as well. It's been apart enough for me to be familiar/comfortable working on it without a manual. I guess what I'm asking is, am I going to have to re-familiarize myself with a whole new type of engine (rebuild process), or are they both pretty much the same (to an extent)? I understand there will be slight changes, which one is more complicated? 2) We usually throw new rings in the CRF250's at 30-40 hours, what is the interval for the YZ450F's for rings/rebuilds ? 3) Is the 2007 YZ450F a good bike or should I go for a diff. year? Thanks guys!