My riding group has an interesting spread of modifications, which we've been able to compare and assess. One bike has the HRC (with cam) kit. Our observation is that (compared to newer bikes and mine with a 440 kit), the cam seems to improve top end and really lets the XR4 breath. The 440 seems to improve low end more.
Both bikes are older and have engine wear, but on flat straight line acceleration are comparable. BTW, my dealer told me that non-factory cams are actually made from stock core turn-ins and have rapid cam lobe wear compared to the HRC cam.
We conclude that the 440 is desireable for trail-riding where more low end is desireable and the cam is desireable for desert and more "flat-out" riding.
The interesting thing is that both newer bikes (2000 & 2001), once dialed in with intake, exhaust, jetting, etc., are just as fast as the older bikes with the 440 or cam. We figure that's engine wear since all bikes have similar non-cam/440 mods.
I did the HRC kit on my `97 XR400 when it was about 2 months old. I considered it money well spent. It *felt* like it had twice as much power everywhere, especially on top where the stock motor would really be wheezing, the kitted motor would run hard to the rev limiter. I also had a Yoshimura full exhaust system on it which worked very well. The HRC kit comes with a taller(about 10% I think)primary drive that you may or may not want(I wanted it 'cause my XR did some street duty). You can get everything except the primary drive seperatly from Honda if you like though. Also I had 0 reliabilty problems the entire time I owned the bike (4 years)
Disclaimer: *now we all know that it didn't really double the output, but it sure felt like it!*
Yes, hardweld camshafts are made from stock cores. The procedure increases the amount of hardface material on the cam lobes by at least 30% over the stock coating, making them less prone to wear than the stock camshaft.
The reason other aftermarket cams may wear more quickly is not because of the way they are built, but because most are running much higher lifts.
The HRC cam increases duration, but does not increase the lift numbers considerably, thus it is easier on the lobes and rockers.
If you run a higher lift aftermarket cam in ANY Honda RFVC engine, hardfaced rockers will reduce or alleviate the wear problem.
Performance-wise, the long duration, short lift HRC cam will give more pull on the top with less change at lower rpm. A "normal" high lift/longer duration aftermarket cam for the XR4 will give quicker throttle response off the bottom, plus the top end boost realized with the HRC cam.