I have done complete top ends on XR400R motorcycles with same exact top end. The only tricky detail is the cam chain timing and chain tensioner. I think it would be better to get a manual for timing details and bolt torque values. Even with the manual I had some trouble with timing but eventually got things together. You could read the manual at your dealer to get details on cam timing and bolt torques. This is better than no manual at all.
Be sure to pull the swing arm pivot bolt and give it good clean/grease. Some guys have had to cut the swing arm bolt and remove engine to finally get things right.

 

Aside from the head bolt torque/tightening sequence, would it be safe to assume that the timing chain instructions would be included in the cam kit? You are right, the part that intimidates me is the cam chain, but hopefully if I don't spin the motor all the marks should line up and all should be well, right?

 

I would say on a scale from 1-10... Its a 7 or 8 on the difficulty level only because there is soo much you can screw up... I did the cam and piston on my 450r and the cam was simple... the piston was a little more work but not much more difficult... Get a repair manual it will walk you right through it... I got mine on e bay on a CD for like 10 bucks

 

Hey I was looking through the manual for my old trx125 and the cam comes out in like 2 steps, probably in less than 5 minutes once the fenders are off. Maybe I'm not understanding this fully but if I mark a spot on the timing chain and put a mark right next to it on the cam gear, how could I mess anything up as long as I reinstall the same gear on the new camshaft and keep the same relationship between the two marks? Forgive me if i sound like a dumbass but the only timing chain setup I've ever dealt with first hand was a chevy v8, so if I'm missing something please tell me. Zettler I just looked at that cd manual on ebay, I might end up going that route as well.

 

i would say a 6 or 7 on a scale of 10. the timing might be the hardest part if you havent done it before. clymer makes a real good manual cost is about 20 bucks walk you right thru it. good luck.