Amongst my recent K75s panel and bits was this. Although disassembled it looks in good condition and worth putting a bit of effort into. I'll either get it back together or go mad trying.  
Regards Martin.

Check with Charlie as he has my old 83 instrument cluster. I had found that after about 35 years bit by bit things started to fail and ended up using the later cluster with the bulb to the fuel light removed. Because the sender unit is different the light would remain on all the time.

Thanks Stan, I've sort of come to the conclusion that the light and the larger circuit board were probably a Japanese only thing.  I wish I could read Japanese? It could possibly be a speed warning light that came on when a certain speed was reached.  I have an idea that I could remove the circuit board I'm missing and leave the light and it's board behind. However I would prefer to keep the early instrument panel intact A/ Because I've never seen it before, and I have searched. B/ Because a mate has an early brick and he might need it someday.

 At this stage it is all assembled ready to go minus that circuit. If anyone has a wrecked instrument pod with the missing circuit board or that circuit board please contact me and we can do a deal.
Regards Martin.

@MartinW wrote:

I'm fluent in Japanese.  That's a "Low on Toilet Paper" warning LED.

Arrr So

Finally had a breakthrough the first two characters are speed the second two are alert. Still working on the fifth.
Regards Martin.

Google has a phone app that reads Kanji:
https://mashable.com/2017/01/26/word-lens-japanese/

Unfortunately my phone has had a lobotomy. It is no longer smart. I am satisfied that the light is a speed warning, possibly to warn when you go into light speed.
Regards Martin

Japan has a max speed of 80kph and most of the bikes I have seen that are grey imports from there have a blue light that comes on if you go over 80 kph

Thanks Rick.

If you come up with a clearer photo of the text I can ask a friend in japan to translate it for you.

Yes it's a speed warning light. One of my cousins had a Jap import Nissan Sunny that had an audible warning that activated at 80 kph. It was very rapidly disconnected with a wire cutter.

Strange.I have spent sometime in Japan and found the highway speeds to be 100kph or higher posted speed and have been pasted by people doing twice that. Although i have never imported bikes I have import dozens of cars over the years, mostly BMW's but Nissan, Honda, Toyota and Mercedes all built for the Japanese Market and none have had a warning light at 80kph.

Some years back there were limiters on some of the cruise controls usually about 110kph. but with the cruise off the cars were normal.

Thanks Gorio I have managed to translate four out of the five characters first two represent speed the next two represent alert.
Regards Martin.