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