Funny that bike should show up...
I bought a similar one with custom paint, in the late 70,s. Said it was 900cc, orange wild custom paint, even the RC pipe ! And it was pricey. It went real good but had long forks, so of course it did wheelies.
Anyway it started burning oil.i had taken it on a 1000 mile trip one weekend two up. I remember racing against my buddies new XS11.
Probably that winter I tore it down, was upset , because they were reworked 350 pistons, very high comp, mystery cam marked Luther..very on or off motor no midrange.
I put a 77 K motor in that bike.. The 900/836 motor then became my 836 I think.. Changed barrels, and hmmmm hope I changed the rods... The 836 was together from about 80-07..... Time to retire those rods!!