Differences in engines through the years... power wise

[My96z]

I hear that the earlier 500 engines were more powerful and that Honda tamed them down as time went on. Figured I would ask the pro's in here for info. Which motor would you prefer for a MX'er?

What are the differences between the KX and CR motors? I know they KX has a powervalve, would that enable it to have a fatter power curve?

Thanks,

Jeff

[Tharrell]

In my opinion, anything Honda did was to make the powerband more manageable. Since the KX had a powervalve, it seems to reason that the pb was engineered to be more rideable.
However, the KX seems to be few and far between today as it was back in the day.
John Dowd did pretty good at the castle recently on a KX500, but his talent level is far above most of the vets there that day.
Honda factory rider Eric GeBoers actually detuned his ride so that more power could be put on the ground.
Horsepower numbers are only one statistic, torque is another.
A good combination of both seems to be the winning combination.
Some of the real gearheads in this group can expand on this.

[Okotokian]

I've never ridden the 85 - 89 CR5s.
-Had an 84 CR5 air cooled model. It started good and spun the wheel lots.
-Stock 97 engine in a 2001 aluminum frame. (hated the handling)
-Now a 2004 aluminum frame with a 94 engine w/ Roosty Maximus w/ ported case, cylinder head, programmable ignition and 38 pwk a/s carb. It is not anywhere near stock and does have some ghost ignition issues that have yet to be sorted (sometimes expect these issues modifying).
The ported engine I'm running now has significantly more torque than the stock 97 engine even with the ghost ignition issues.
I recently took it to the mx track and rode with a friends stock KX5. The kx is probably has some decent hours and probably not optimized jetting wise but ran good. The kx was lacking jam on the low end but did build to pretty impressive revs which didn't work well on the track. Kx was smooth engine that needed more shifting than I expected.
That said, comparing to the ported CR5, CR has so much more torque I basically left it in 3rd gear, shifting to 4th on the straights and slipped the clutch around corners and torque do the work without needing to rev it out like I had to do on the KX. Keep in mind at the time I had tall gearing too at 14/48.
The ported CR was far superior to the stock KX it wasn't even close that is until my ghost ignition problems reared the ugly head.
There are however lots of gaps in this story without knowing the real history of the KX5 I was riding with. The KX will need some real tuning & mods to come close from idle to 2/3rd throttle range.
btw I'm in Egypt as well but in the western desert.