New project

Good spot. The "pins" (cylindrical pieces at the corners which retain the side seals) should have "springs" behind them, which push them out into firm contact with the end (or centre, intermediate) plates.

On stripping, a few of these pins did not have these springs to apply force "outwards". Omitted during a previous rebuild we would have to assume.

This is likely the cause of the blow by. Presumably also not helped by the scuffs on the end plates, and as it progresses more and more carbon builds up making sealing even less efficient.

Hopefully I will be able to replace these springs (not from Andover, tho, as they are NLA ... ) and allow the rebuilt motor to be better than it was in a previous incarnation.

Fiddly indeed!!

Andy

Ok some some progress.

A nice man took my cases to get cleaned up (he also did my rotors and the eccentric shaft, not being at all impressed with my efforts).

He then skimmed them to clean up the scuffs, measured, checked, did clever things, and I came up to (watch him) build the motor.



He had already chemically etched the fresh end plates and put the stationary gear and studs back in.

The mating surfaces of the rotor chambers are coated with Wellseal.



Much cleaner. Embarrassment. These beautiful big roller bearings are very expensive. The eccentric shaft has been hot, but is usable. NLA, so I would likely have been looking for another motor if it were gubbed...



1st rotor (right) and shaft. Note the side seals and springs (underneath) are fitted to the rotor here, but not the apex springs and seals. (Also eye-wateringly expensive)





Apex seal, with spring hidden behind it.



Left hand chamber and rotor. The side seals total free play is 5 thou to 7 thou, against the 2 corner seal pins.


And put the top on.



11? (very expensive, of course, non standard, and strangely one of the few imperial fasteners) nuts behind the alternator rotor/ flywheel. I can probably take 4 or 5 or the 7 kilos off of this, but I want lights for now (and setting up idle etc), so it will stay as it is. And its a relatively easy thing to. Hmmmm. Thinks: may look for a flywheel to play with tho....

The engine itself is really beautiful internally. It appears, to my very untrained eye, to be really nicely engineered and developed.

(ok, not perfect, a bit hot maybe, but...)

So I also got the gearbox at the same time. The kindly uncle also drilled out a seized centrestand pivot bolt, meaning, I can rebuild the gearbox. I got it stripped, and am glad I did...

The gearbox bolts onto the face of the primary, driven by a duplex chain. 3rd and 4th gears apparently get noisy on these. So we want to replace as a pair, right? Ideally. I think its a T140V derived box, and the 4th and 5th gears are captive on the layshaft. Of course. So I have spoken to Graham at Startright, and got the gearbox stripped. It was suspiciously clean inside, with quite a lot of case hardening on the magnetic plug. The case hardening has started wearing through on the 3rd & 4th gearsets. Graham to advise. So I cleaned about 30,000 miles worth of road dirt off the box, and waved a spray can at it.

Lets see how this bit pans out...

Andy