oil in frame Domiracer?

Looks like a heavily reworked cylinder head. Pre '59 with wide bore exhaust ports but modified to steep downdraught inlets?

A lot of work has gone into the bike. Not oil in frame though. 

Oil in the frame is for lubricating primary chain. Same parts as on a Manx. Though I'm not allowed to use it as the race scrutineers don't allow oil dripping from a bike.

You fill oil oil through a small internal thread stud on the left top frame tube, quite close to the steering head. Then you have the tap clearly visible in your picture #1. The rubber or plastic tube down to the twin nozzle piece that feeds the oil to both sides of the chain rollers. There is Amal main jets in it, which can be changed for more or less flow.

Hi Mikael

Direct oil feed to the end of the camshaft must prove provenance.

Any chance you could write an article on the Domiracer(s) for the NOC magazine, Roadholder, please?

Information on these rare bikes is sketchy in the usual Norton books.

Apparently Doug Hele and his team tried many configurations but articles usually end by saying that when the race shop was shut down and Paul Dunstall got a lot of components, no tech info or drawings were there so development stagnated.

Any help appreciated.

Tim S

Interesting the engine number is from 1963 but stamped in unusual location, yet the head is earlier. I wonder why the earlier head was chosen and then made more like the later? Also...what is the little mark above the number? Looks a bit like a later variation of the mysterious pawnbrokers' balls signs on many but not all prewar Inters. 

The direction of the lock wire on the exhaust rose can be changed...

This engine has a standard late 1950s T2225 head onto which appears to have been welded the top fins, front and rear ports from a 650 22707 casting. This would need a great deal of serious welding to achieve a good result and possibly it is more likely that somebody had access to the casting moulds in order to create their own special.

As the T2225 head had smaller inlet valves and I guess these were enlarged during the build.

The engine number appears to be 101431 which puts it in the middle of a February 1962 batch of Nortons. I am wondering if this was one of a batch of 50 short stroke Norton 500cc engines built for Gus Kuhn in the 1960s.  These had 68mm bores, 650 pistons and specially made (68mm short stroke) crankshafts..

Adding a bit more to this interesting motor.
The bike was built at Bracebridge as a special order Model 88 to Daytona Spec. In which case it should have been sporting a proper 22707 SS cylinder head with twin horizontal carb mountings. tuned head, possible lightened rockers and crankshaft, racing Magneto and other 'go-faster' additions.
When completed it was shipped out to Berliner in the States.
The head it is wearing is around 5 years older.