Honda-SOHC

I did it with the VFR. I didn't even know until I pulled out from the forecourt onto the main road and it died. I pushed it the two miles home and drained 15ltrs of diesel into three jerry cans and gave them to my neighbour for his van. I had to replace the fuel filter in order to be able to start the bike.

Petrol floats in Diesel so it will probably soon soot up the plugs then start to misfire.
Anecdotal Story
It was a long time ago but an lovely Irishman (Keith Dunne) I worked with used to put diesel in his petrol car to save money as in the 1960's it was cheaper- he drove a Standard Vanguard - it would smoke like the clappers and eventually it seized up.

Haha! It happened to me once when working in an australian farm. I filled up a quad bike to the pump dedicated to diesel tractors, whistling to that beautiful morning coming up. It smoked a LOT and finally stall 2 minutes later, and I learnt a LOT of new cursing and swearing in english from the local mecanic!

He drained the whole thing and cleaned everything with gasoline, the bike started as new and I went back to work fairly ashamed 

Did it smoke a lot?    I nearly did that once but a sharp eyed attendant rescued me!

Good point I'm going to get the fixed bearing fully home as it was before. I'm thinking the right side will move back out a little but not as far out as it was.

I understand the fixed bearing principle - the lock ring seems to have two functions. Securing the fixed bearing and holding the drive hub fully home.

Update:- I removed the lock ring (again) and using a drift with a good sized lump hammer the left side bearing is fully home. The hammer strike changed tone as it butted up to the recess. Drive hub and lock ring fitted back and it's fully tightened with no gap visible between the ring & hub face. Visually the right side bearing has moved out slightly but nothing like it was.

I now have a slightly different issue that existed before I stripped down the bike - some light binding. The rear brake linings have a very slight bind.  I had to file the brake shoe ends where they pivot as there was no room for the top washer only the split pin. The brake shoes also appear to be a tad wider than what feels right when you fit the brake hub it's a difficult wiggle.
 
There is no free play in the brake shoe system. A very slight amount of lever movement in either direction applys the brakes. It's diffucult to pin down but it feels as if the binding is more like the side of the brake linings touching the inside of the hub.

From previous posts it appears that the original brake linings are no longer available so it's a bit of a raffle to get the correct ones. My next move is to see if a chamfer on the inside edge of the curved shoe might improve things. I think but am not sure that the hub has had a new steel lining fitted in the past.

I'm going to remove the brake shoes and re-fit the hub to be 100% sure it's just the linings causing the bind.