If you had a shop manual, some mechanical ability. Could you rebuild the top end of a 98 300EX? My brothers just bit the dust. We ordered a piston kit, clutch kit, valves and valve seals for the rebuild. Has anyone attempted to do one by yourself for the first time? Thanks.

 

Four stroke top end is no real problem,I did one for the first time when I rebuilt my Wolverine,as long as you follow the manual,you will have no problems.The main thing to watch is the cam chain,don't let it drop into the motor,or you will have to take it apart to find it!! And put rags into all the holes,I dropped a piston circlip down by the cam chain,and got luckier than HECK to get it out with a long skinny magnetized screwdriver. If you have a decent shop nearby,and if you have the cash,having the head off is a good time to have it ported,helps with the top end power,and keeps it cooler if you are running a high compression piston. One final thing,if you plan on real hard trail riding,or do any hard hill climbing,or anything that really heats the engine up,an add-on oil cooler really helps,Four Stroke Tech sells one for 95 bucks,dropping the oil temp keeps the power output from dropping on the hot days when you really work the motor hard.
You said you have valves also,if you have the tools,putting them in is no problem,I had mine done at the shop, getting the seats ground is needed with new vavles,so I figured,why not let them do it all. I hope this helps you out,just take it easy,keep track of where you put all the parts,and it should come out fine (mine hasn't blown up yet!!!)