If you believe so then make your case with facts and/or data.

a) different part numbers

b) dyno tests

c) measured cam profiles

Well, my understanding is the cam profile changed and part no did not change. I have seen this on a number of K parts where they were modified in the production run, after buying brand new and used parts based on part nos. Very early Ks don't have the same front calipers! Smaller pistons! Seems they came out of the R bike parts bins...like the push button fuel cap...

I am tempted to do dyno tests as I have 3 Ks that fit the category of early Ks. I also have an early engine I could dismantle. I have a very lively K1100 to compare them to, their performance above a certain speed is definitely superior to the K1100 and very silky smooth. 

For the time being all I have been able to do is ride them back to back and with similar conditions as in fresh air filters, same injectors etc.

The K100s that were sent to North America had different intake cams. The intake opened 20° later than the European models.
This has the effect of lowering the compression at lower engine speeds and a slight reduction in burn temperature which in turn reduces the nitrogen oxides produced.
It was the emission standards in California that was the reason and the rest of North America had to follow along.
There was a very slight reduction in low end torque and a very slight reduction of Horse Power in the top end, most riders would not pick the difference.
I am not sure if the K100s sent to the rest of the world had the same cams fitted at that time.
I have posted the numbers many years ago here and on the Motobrick forum.
As for the cams being "hotter" don't waste your time changing them or trying to get some it would be a wasted exercise.

Rick G wrote:The K100s that were sent to North America had different intake cams. The intake opened 20° later than the European models.
This has the effect of lowering the compression at lower engine speeds and a slight reduction in burn temperature which in turn reduces the nitrogen oxides produced.
It was the emission standards in California that was the reason and the rest of North America had to follow along.
There was a very slight reduction in low end torque and a very slight reduction of Horse Power in the top end, most riders would not pick the difference.
I am not sure if the K100s sent to the rest of the world had the same cams fitted at that time.
I have posted the numbers many years ago here and on the Motobrick forum.
As for the cams being "hotter" don't waste your time changing them or trying to get some it would be a wasted exercise.

I found that changing my USA '87 K100RS with an '85 intake and exhaust cams made a noticeable difference. A friend at the time also has a K100RS and we switched bikes for a test. He said, "I wish mine went like that!"

Glenn

Rick G thank you for that post.

Your comment about the top end is precisely where I notice the difference.

The vacuum sensor fitted to early Ks, perhaps its where it has some effect. Everyone agrees 'it does nothing' and they do run fine without it but maybe it did something at the top end.

More info from my old notes:

These are the number from Max's
http://www.maxbmwmotorcycles.com/fiche/diagrams.asp?mospid=45546&VIN=&hg=11&fg=3
0&model=K100RS

-01 11 31 1 461 525 Inlet Camshaft 256 GRAD 
-01 11 31 1 460 045 Inlet Camshaft 284 GRAD  - 1985 High Lift Intake

-02 11 31 1 461 526 Camshaft Exhaust 256 GRAD
-02 11 31 1 460 044 Camshaft Exhaust 284 GRAD - 1985 High Lift Exhaust

Duration for high lift = 284°
Duration for NA lift   = 256°
284° - 256° = 28° longer duration

1985 Camshaft Specs
-------------------

The base diameter is 1.18"

The height difference is 0.04 to .05"

Standard is 1.50"

1985 cam is 1.54 to 1.55"

1.50 - 1.18 = .32 lobe lift
.32 + .04 or .05 = .37

.37/.32 = about 15 % more lift

***********

"The K100s that were sent to North America had different intake cams. The intake opened 20° later than the European models" (Rick G)

"Around April of 1985 BMW began selling a 50 state legal bike in the US (note: there was never a "California" model as such). These came with 256 degree cams, costing 7 horses and taking away some of the original top end rush." (TheMason)

"I believe the only difference on the cams were between the 85 and 86 model. The 85 has 10 more HP." (Crazy Frog)

****


Glenn