Before you start saying wrong forum, understand that I dont like the YZ/WR250F forum because most of the people on there are younger kids who dont know what they are doing. That being said, we need help rebuilding the top end on my dads '02 WR250F. We havent cracked the case yet but we are just going to go ahead and replace everything. valves, valve springs, cams, cam chain, piston, piston wrings, gaskets, and everything else that I am leaving out. The bike is 5 years old so I figure that I might as well go ahead and replace everything. (Do I really need to replace cams? If I need to I will prolly do the auto decompression cam and may even get aftermarket) Part of the reason why we are doing it now in the middle of the summer riding season is because it wont start. It hardly has any compression and we are thinking that this is why it wont start. When we first got the bike we COULD NOT even begin to move the kick start when it was at TDC w/out the compression release. Now, it feels like my KX125 did right before we rebuilt the top end. My dad and I both think that the lack of compression is the reason why it wont start seeing as it was getting gradually harder to start as it lost compression. My dad is offering to take it to the shop and have them do it but I dont want him to have to pay $1000 and besides, I want the experiance of messing with a four stroke engine. I was going to get a motopower video and use that but there wasnt one for my dads bike so I figure that I would just use the manual we have. The only problem is that I dont know what tools I will be needing to do the stuff that I am talking about. I do have a basic tool set. I am kinda nervous about doing this major rebuild. Should I be worried? I am considering refreshing the motor on my '03 450 while I am rebuilding my dads top end. What should I do to it? I havent done anything AT ALL except for basic maintenance. I have been very good about the maintenance but I have had the bike since novemeber and I figure that it is probably time to do something. I appreciate all of your tips!