I have rebuilt several primary units in the past making this
one pretty straight forward. One issue encountered has been torquing down the
spindle nuts without spinning the rear wheel. To head this off the cylinder was
left off and a steel rod was put through the connecting rod small end bearings
to keep the engine from turning over. This also worked well for the
transmission & timing gear assembly.
The primary was shot on this bike. One of the inspection plugs
was left out and covered, somewhat, with tape. The primary had a lot of dirt in
it as a result. A used primary was purchased from the same seller on ebay that
sold the transmission to me. I installed new seals, rubber buffers, and fiber
plates in the clutch. An old BSA dealer told me that Emgo plates do not stick
as bad as Barnette plates, which I have had issues with. Since I will not ride
this bike hard I went with the Emgo plates. The steel plates checked out flat on a surface
plate and are being reused. While I had it apart I also filed the burrs off of
the clutch basket. They were not very big but cleaning them up should
facilitate smooth clutch plate movement. Once the pulleys were fit I checked
sprocket alignment with a depth guage.
The primary chain had also run out of adjustment. To make up
for this a previous owner had welded a lug nut under the adjuster, which can be seen the photo above. The down
side to this is that the chain had slapped against the case and worn groves
into it. They look bad but no significant damage had been done.
Primary assembled except for the clutch springs and pressure plate.
An Emgo fiber plate with a factory steel plate.
The ET ignition system is going away on this
hornet. While putting on the rotor I found it was mounted to a plate with
location holes in it. It seems this is an adjustment for ignition advance with
the ET system. I turned the spacer plate around which put the pin to the inside
of the bike and then located the rotor with the key. I also put a stator from a
1970 thunderbolt on the bike. I am not sure if the ET stator would have worked
with standard coils. The stator wires were cracked which was rectified this
with “liquid tape”, a pointer from a friend in Idaho. Thanks!
