Sunday 7 June 2020

Remaining Engine Components

The main engine components which have not yet been covered are the cylinder head, oil pump and magneto.

The valves, valve guides, springs and spring retainers were all replaced as a matter of course, a straightforward job.

The magneto that came with the bike was not reclaimable and a replacement rebuilt Lucas KR1 racing magneto was fitted. These are difficult to find and command high prices!

The oil pump had suffered badly from corrosion and it looked as if it had been submerged in water for many years.

These externally-mounted reciprocating pumps are unique to AJS and, I believe, unique to the OHC models.  These are pretty well impossible to replace – I have never seen one come up for sale - or to easily manufacture. The options were either to repair this one or to fit a completely different external feed/scavenge pump.

I chose the former option as the corrosion, although significant, was limited to the area than can be seen in the picture. The rest of the pump, including the main steel reciprocating element and drive gear, was in good condition.

After using a dremel to clean up the corrosion, the pump looked like this:

Here, it can be seen that the corrosion has eaten it’s way into the pumping chamber. The damage was repaired by:

     - Making a brass insert to support the input drive shaft

     - Putting a dummy spindle into the pumping chamber (to avoid Devcon spilling into the chamber)

- Filling the corroded body of the pump with Aluminium Devcon

The pump was tested after the repair and functioned perfectly. The repair is extremely strong and I do not expect further problems.  

No comments:

Post a Comment