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Old 01-14-2013, 04:45 PM   #28
Carl's Avatar
Joined: Oct 2001
Location: South Tejas
Oddometer: 770
clarification and commentary...

For the 1955-69 Twins:

Generally all factory equipped Earles fork machines had sidecar lugs. For the late '68 & '69 machines they generally always were sold with frames that had the sidecar lugs not installed at the factory. any mass production source of a product there can be factory one-offs. I've owned one '69 R69S Earles fork machine that was built at the factory w/out sidecar lugs and I've owned one '68 R60US that was built at the factory that had a frame w/ sidecar lugs. Both of those bikes were here in the States being passed around in Ohio ~15 plus years back.

As per the charging systems, there are three factory designs:
  • 6V, 2-brush generator
  • 12V, 4-brush generator
  • 12V, 2-brush alternator

All three of the above charging systems retain the factory magneto design. W/out a battery the lights will function at charging RPM rate on the generator designs. W/out a battery the lights will not fucntion when the engine is running on the alternator design. The generator designs are used early through late in the Twins production range. The alternator is a late design as it is basically a /5 charging system. A 12V factory charging system does not mean the magneto is deleted. There are also various one-off, not from the factory, design chargings systems that are available for these machines.

Now for the rebuilding of gearboxes on the 55-69 twins...I consider the 'proper and correct' rebuilding of these gearboxes far more challenging for the novice that the '74 and up BMW Twins' design. In just the past year I've had two 55-69 Twins gearboxes sent to me that riders did not get 'right' (as in botched) when doing the rebuild. Yes, a rebuilder can do one for their first time and get it 'right'. Yet not being aware of their uniqueness and thinking it is a simpleton task can lead to a an expensive lesson.

That bike appears to be a very decent buy by today's market values. They are fun machines that have proven themselves to be an excellent design exercise by the engineers that made it happen.


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