after spending hours and hours reading on this forum (and others) ;
i have often seen this sentence used : THE FINEST YEAR OF K100 1985:
my question is :  is it so , and why?

regards k-rider

The American guys will give you a more detailed explanation (as it only relates to the US models). As far as I remember, the 1985 K100s in America had the standard European cam profiles, while the later US models had a softer profile. Therefore, the 1985 models had more power.

The US guys will add to this when they get out of bed.

Corkboy wrote:The American guys will give you a more detailed explanation (as it only relates to the US models). As far as I remember, the 1995 K100s in America had the standard European cam profiles, while the later US models had a softer profile. Therefor the 1985 models had more power.

The US guys will add to this when they get out of bed.

oh,ok, learning every day
thanks:D

It's because I have one.

A tongue-in-cheek statement about the 1985 model.

Welcome aboard, probably the finest year was the last year of production because by then all the small but significant improvements had been made plus hopefully the reduced toll of time and wear would help.
Regards,
K-BIKE

I read an article that did a dyno and found 77.7 BHP at 7900RPM.*

That, however was a very early model. Needless to say I'm skeptical about the 90hp claim, as well as a tall cam, short cam, etc. Without some concrete evidence how can we tell for sure?

"Rising Hun," from Mechanics, December 1983, reprinted in BMW K100 Series Performance Portfolio, 1985-1993, compiled by R.M. Clark, Brookland Bros LTD, Surrey, England, p15-16

My K100RT was first registered in the UK 26th March 1985 (VIN 0024022) according to the reg document.  It has very nearly 110,000 miles on the clock and has already outlived my 1993 K1100LT, which lost cylinder 3 a while back.  This wonderful machine took me around Europe 4 years ago (4,500 miles approx) and is still running sweetly.  I use her at least once a week in my capacity as a motorcycle instructor and I still enjoy every mile on her.  Does she qualify as a FYK ?

AJ.Valente wrote:I read an article that did a dyno and found 77.7 BHP at 7900RPM.*

That, however was a very early model. Needless to say I'm skeptical about the 90hp claim, as well as a tall cam, short cam, etc. Without some concrete evidence how can we tell for sure?

"Rising Hun," from Mechanics, December 1983, reprinted in BMW K100 Series Performance Portfolio, 1985-1993, compiled by R.M. Clark, Brookland Bros LTD, Surrey, England, p15-16

The difference in camshaft profiles was that the US models had the inlet valve opening 10° later from 5°BTDC to 5°ATDC other than that they were the same including lift. This in effect gags the inlet and lowers the compression ratio because there is not as much gas to compress which in turn lower the combustion chamber temperature and that lowers the nitrogen oxides that are emitted so less polution. I am not entirely in favour of this because then you cant see what you are breathing and is that safe.
As for 90BHP that is measured at the crankshaft and to be honest getting 77.7 at the rear wheel is very impressive considering there are 3 counter rotating shafts in the gearbox and a change of direction of rotation at the rear drive. I would have expected somewhere around 67 -69 BHP at the rear wheel.

This is how civil wars start  

I reckon there's probably something to be said for the most simple 'K' i.e. with no ABS and a completely bullet proof 8 valve engine being the 'best' in terms of fewer glitches and probable engine life?

That said, the 16 valve has more BHP, better forks and brakes, radial tyres and a paralever. The 16 valve exhaust, I think, is not too clever as it's a single piece, so when the welds go you need a new system.

Then again there's fairings to get worked up about. LT/RT have their proponenets as do RS's. For some the K1100 RS fairing (someone suggested on a K75) is the best.

I reckon mine's the best when its working well and a useless piece of junk when it's not.  

Cheers
Dave

I know my '85 is the best year, but it is a usless P.O.J. now, as the bike dies when I plug in the fuel pump connection.
It makes 45 psi. Am I missing an electrical feedback to the brain?

Sorry to see you have a problem.

I was just trying to work out how it dies when you plug in the fuel pump connection. It must surely be plugged in to work? Is it a connection elsewhere?

Anybody give me the date of manufacture from my VIN No:029453-100rt. It was first reg.d  1985 and bought from Gedges in the south west. I bought it 3yrs ago, with 4000 miles registered, now done 18+K. Best machine I have had allround. Other bike--R80rt 1984 mothballed at moment.

Gordon,
Have a look at the second set of numbers in the engine number, it will be something like:- 1785....that would mean that it was produced in the 17th week of 1985.

Paul.

Many thanks Duck but it keeps throwing my request out--don't know why, thanks Paul,will look tomorrow.Be nice to know when she was actually built. I'll post when built many thanks Gordon:D

Add an 0 to the start of the number. Needs to be 7 characters

Chassis number	0029453
Vehicle code	0504
Series	K589
Model	K 100 RT 84 (0504 ( 0505 )
Body type	K 100 RT 84 (0504
Catalog model	ECE
Production date	1985 / 07
Engine	0514)
Transmission
Steering
Catalyzer	NONE

Disclaimer: The following is based upon what I've learned about FYKs over The Internet through the years and, therefore, I do not vouch for it's credibility but I THINK it is correct.

The very early 85 K100s shipped to the US were not available for sale in CA because they did not meet California emission standards for two reasons:

1) The exhaust (I think CO-wise) was non-compliant.

2) Fumes from the gas tank would vent to the atmosphere and Dog forbid the state of California might end up with one or two ppz (parts per zillion) molecules of gas floating around in the air.

In response to this, BMW "detuned" the cams a bit to get the CO down which supposedly reduced high RPM horsepower by X horsepower  (I've seen five and seven used often) and routed the gas fumes to the front of the engine block.

From what I understand (please reread my disclaimer above) the "true" FYKs do not have a vent pipe on the top middle front of the engine block while the later ones do.



I think the easiest way to tell is to look under the middle bottom of the radiator for that vent pipe on the front of the engine block.

As some others have stated, there doesn't seem to be any indication in the parts catalog that the cams ever changed (no superceding/different part numbers for K100 cams.)

My thanks to all,it seems mine was built in week 28 1985 . It's beginning to loosen up now and running in appears near to completion. Best wishes to Oz we're thinking of you.

I did some work on the ignition switch. Was under the fuel tank, deoxiting the switch connector.
If I hang a fuel cell above the bike, with a return line, the bike idles perfect, and fuel flows back to the cell. With no pump?!?
Then, I restore the fuel tank - no start, but I have 40psi showing (have a gauge). It fires a bit then nothing. With residual fuel pressure, when I unplug the pump connector, it will start and idle a few seconds.