If it has chain drive it's either a XV 920 or a TR1. In my Haynes manual, that covers all XVs and the TR1, I can't find the engine number 5E5. There is 5H1 for the XV 920 and there is 5A8 for the TR1 (both models). What is the frame number?
There are a few conversions around such as a XV 750 with a TR1 engine. That a lot of work because the left crankcase half is different because of the shaft drive. XV 750 with XV 920 or TR1 cylinders and pistons might be possible as well. I don't know.
If you have the chopper model tear drop petrol tank, it's a XV 920.
If you have the normal touring type petrol tank, it's a TR1.
If it has the rear mudguard that moves with the rear wheel and a square box behind the seat, you have the early type TR1 (5A8).
If you have a rear mudguard that's fixed to the frame and a tail light that's integrated in the seat unit, you have the later type TR1 (19T).
That's all I can say about it at the moment.
Regards,
Harry Spruit

To distingish the 5A8, older type TR1, form the 19T, later type TR1, look at Manfred's TR1 page. Probably the previous page before you got to this one. The silver one is the old type and the red one is the new type.
As being a Japanese import I have no idea about its cubic capacity, but its its either a TR1 or a XV 920. Not a XV 750 SE, because that one had a shaft drive.
Of course it may one of those special Japanese capacities, since they have a driving licence for small capacity (I tought up to 400 cc) and a driving licence for big bikes (over 400 cc or something).
I also heard another story about a chain driven very early 750, that was only sold in Japan and Australia, but I was unable to verify that story. So I might just be what it is: a story.
Harry Spruit

In the US, a chain drive 750cc engine was offered for a time to help start a dirt track effort. I don't believe they were widely used, so a few may have found their way into road bikes...just another possibility to consider...

haven,t got a clue what bike it is but welcome  to the site , let,s have a pic. of this cycle .

Hi Claire,
        I think you'll find that your bike may be the 750 virago (usa) model.  If you look under the seat you will find a collection of relays, one of which is for the flashers, if american, 1 for the hazzard warning lights, and either two or 3 for the starter circuit.  if you have an extra one connected to the sidestand, then you have an american import, if not then it was meant for the uk/european market.
that any help?
Dave