74 Alpina

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yamfan
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74 Alpina

Postby yamfan » Mon Sep 04, 2017 9:26 pm

Hi, I just brought a 74 Alpina which is totally original although she does have a lot of surface rust and no spark.
Its early days yet but there is a lot of corrosion and moisture in the flywheel so I might just bite the bullet and go electric ignition rather than fiddle with replacing points, condenser and coils etc:
Does any of the 'Brains Trust' on this forum know how close the Alpina is to the same years Sherpa, is the footrest location, wheelbase etc: close enough to ride Clubbies when i'm not killing myself on a sidecar.

I have been looking for a good Sherpa for a while now but people are asking so very optimistic prices so when the Alpina came along at a very good price it was a no brainer.

Thought's?



JC1
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Re: 74 Alpina

Postby JC1 » Tue Sep 05, 2017 9:07 am

Main difference in geometry is in the triples, so if you want Sherpa steering (which is far better for trials), fit Sherpa triples.

The diff is that the Sherpa's have inbuilt angular offset whereas the Alpina's don't, which gives the latter much more trail, causing the steering to want to flop-in more in the slow tight turns common in trials.

If its a 115/116 model Alpina the swingarm should be the same length as the Sherpa's but overall wheelbase is about 20mm shorter than the Sherpa's on account of less offset in the Alpina's triples. If its a 137/138 model the swingarm maybe 20mm longer. (Also if its a 137/138 check for cracks in the frame/gussets as they were fragile & fractured everywhere.)

Footpeg location should be the same as for Sherpa. Top rear shock mount is in diff location to sherpa but makes little/no diff for trials.

I say "should" on all the above because Bultaco often changed things mid-model.


Summary of Alpina/Sherpa differences here:

http://www.trialscentral.com/forums/top ... es/?page=2


"Men are never more likely to settle a matter rightly than when they can discuss it freely"

David Lahey
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Re: 74 Alpina

Postby David Lahey » Tue Sep 05, 2017 4:24 pm

If its a M99 or M85 Alpina they came with the same triple clamps as the Sherpa T of the time and the bottom triple clamp is made of steel.
Later Alpinas had aluminium top and bottom triple clamps which are different geometry to Sherpa T aluminium triple clamps.

You should be able to tell what model frame it is by the frame number stamping on the steering head.

The reason JC and I are not sure which model Alpina you have is that they made a few different models in that era and Bultaco did not believe in the "one model one year" process


relax, nothing is under control

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whitehillbilly
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Re: 74 Alpina

Postby whitehillbilly » Tue Sep 05, 2017 7:00 pm

Many years ago, a mate tried Trials with an Alpina. (model and year not known)
It struggled with low down torque. I had read somewhere to turn the piston 180 degrees, which we did.
It transformed it to a different bike, with lots of low down grunt. Think we dropped out the base barrel gasket.
Piston skirt must have been different on the reverse side.
Think we may have raised the forks 20mm in the stations, above the top ????

whitehillbilly




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