Thanks to the new kind of fuel we have here, and the fact that the bike has been left alone for a year, the problem of too high fuelpressure let my K run like a drunk.
Reading about every interesting topic here, Sidecar Paul mentioned about a regulator in the pump itself.
Took te pump out, and found the bugger.

Now will share my pictures from the inside of the pump;









This is the actual pump without the motor, before you take it apart, mark some things that everything goes exactly back to where it has been before;




Here is the regulator from the inside, if it's stuck, push it gently with a soft tool down. I took the cap of a BIC-pen.


Here it is on the outside, if you don't open the pump, and have a small telephone pliers, you can pull the pin in the middle;



Before cleaning;



After cleaning;



Put the pump back together, the O-ring goes in first in the aluminium can, then the pump;





Watch out removing the 2 clips wich hold the motor in place, they are not easy to find when they try to escape, and hard to get in the open world (store)  

Nice one Wheeldigger,  good to see the innards revealed..... and great pictures. 

Paul.

A note in passing (which doesn't seem to apply here); if the commutator is covered in grey carbon from the brushes do not polish it. Rub a clean cloth around it to remove any excess. The grey stuff is filling in miniscule pits in the copper and is actually creating a larger contact surface for the brushes.

By all means carefully scrape the dirty stuff from between the copper segments.

Comment also applies to starter motors and alternators.

Not trying to be a killjoy but a few of us have been down this road before when the pump has died.
Can't think of anyone who was successful getting it back together and working again.
But, prepared to be proved wrong! 

I would think that anyone clever and patient enough to strip it to that level would also be able to diagnose any faults and sort the pump out.  I'm not sure I'd be able to do that, but there are an impressive number of talented riders on this forum....

I did put the pump back together, placed it back, and is running fine.
All problems I had before are gone now.

Little add from Rene;

Rene; Although I appreciate the pictures the info is not correct. The FPR is sufficient to keep the pump pressure at 2.5, even if the bike isn't running (at which time the biggest volume is pumped through the FPR). The relieve valve in the pump opens at a far higher pressure (6 IIRC) and is only there to protect the pump in cases there is a blockage somewhere.



Rene; It might be that for whatever reason the pump safety opened and then didn't really shut or dirt prevented it to open in the first place. Somehow rust accumulates there.