Third time lucky. My post seem to screwing up like my bike.
I have done the starter button test. Pushed it while bike at idle and running temp. The revs go down slightly. So it’s a little rich.
The gauge I used is a cheap one in branded from eBay.
By factory I mean putting the vacuum on throttle body four and capping the other three.
I rode it to work today and it ran very well.

Might be time for an Italian tune up.
Regards Martin.

This is the faulty fuel pressure regulator. I purchased on e bay. The part itself doesn’t have any detail on it, nor does the box. It was advertised as part to fit 1985 K100rt and the others. Lost
out on this one.

What is the part number?  Is there a number on the box or on the regulator itself?

Nope, nothing stamped on part and nothing on box. I would suggest staying away from the fuel miser range. The next one I will by and test straight away.

Hmmm...  How would they know what they have?  Their website seems to hint at warranties.  Have you tried to return it? 

Did you say you got it on eBay?  If Fuel MIser tries to stiff you, get eBay involved.  A couple of disputes and they will cancel a seller's ability to list stuff on their platform.  I had a problem a couple years ago, and starting a dispute got it sorted in short order.

Gryph a couple of us got stuffed around by an eBay seller falsely advertising tyres that are available. After a week of not receiving a notification of despatch I got onto them only to be told they had no stock. Another member also ordered the same tyre 3 days after my order, he received a confirmation of the order and a despatch conformation. After three weeks with no arrival he contacted the seller only to be told there is no stock and was offered another brand. I've sent two complaints to ebay and he has sent one with no response. The add is still running showing 6 sold 3 available I ordered my tyre 12/01/22. I went on the ACCC site and found this 

Bait advertising

Bait advertising takes place when an advertisement promotes certain (usually 'sale') prices on products that are not available or available only in very limited quantities. It is not misleading if the business is upfront in a highly visible, clear and specific manner about the particular product 'on sale' being in short supply or on sale for a limited time.
Regards Martin.

Martin, are you saying that you paid for a tire that the seller didn't have and that they wouldn't refund your payment?  And then eBay wouldn't go to bat for you? 

What you describe is called a "bait and switch" over here.  Advertise somehing at a great price and then get the customer to accept either a lesser product or pay more for a substitute.  That will get you in trouble here.

I don't know who the original poster purchased the bad fuel pressure regulator from, whether or not it was Fuel Miser or a reseller, but when I visited the fuel miser website they indicated that their regulators were sold with a two year warranty.  I would think that in any case he should be able to get his payment back for the bad regulator, especially since Fuel miser posts no pressure specs for their regulators and it appears that they don't even sell them for motorcycles. 

If it were me, I would ask the seller for a refund and if they didn't give it, I would start a case with eBay.  There is no reaason he should be stuck with an incorrect part because of false compatibility information from a seller. 

eBAy terms of service state that purchases can be returned if they are not as described.  In my world, a BMW K100 pressure regulator that does not provide the correct pressure is not as described.  Period.

Gryph we both got a refund, however eBay ignored our complaints and the ad is still running.
Regards Martin.

Here’s a e bay pic of the sale I looked up. Ive sent them a pic of the high pressure and a note. See what happens . The eBay return window has closed but I’ll be happy with a replacement that works.

Spares box have responded with a link for me to lodge a warranty claim. So I’m hopeful it will get sorted.

This is the fuel pump kit I purchased. It does work well. However I enquired about it being noisy. Without question they refunded me. Now I know it was noisy because of the pressure it was under. Nice and quiet now. Was a perfect fit with all the parts shown included. The filter it came with seemed a little on the cheap side, I’ll replace that sooner than later.

After kicking and screaming to all parties, being the seller, ebay and PayPal. PayPal have granted me a refund. This is providing I return the item in original packing to ebay. I’ve been given an address to send to. Once I’ve done it I then send the postage info to PayPal. Lucky I kept the packing. The seller gave me false links to follow on several occasions, it seemed they where just trying to break me down. Good result in end. Thanks PayPal.