Alpina with Sherpa parts?

[atitagain]

When I was 15 my father bought a brand new Bultaco Sherpa, needless to say I spent more time on it than he did due to his work commitments. I loved it, super reliable and great to ride. Come forward 40 odd yrs and this (what I thought was a Sherpa) came up for sale locally at a reasonable price. it's all there, yes needs some work and a restore/rebuild but it doesn't look too bad. 

After checking the engine and frame number it seems it's an early Alpina M-8500619 and 9700356. I have had a quick search and it seem that these early Alpinas are basically a Sherpa with slightly different gear ratios. So here are my questions, I know this is the place to ask. Does it look like to you that is has a Sherpa tank seat until or any other Sherpa parts? and am I correct in my assumptions that it's not too far off a Sherpa? 

I am basically pleased with my purchase either way, I'll restore it anyway but I just wanted some expert eyes to see what others think. Thanks

[feetupfun]

The tank/seat is from the first series of Alpinas (models 85/97/98/99).

Being a model 97 (Alpina) frame it will have an identical frame and front end and wheels to the series 2 model 80 Sherpa T.

The model 85 internal Alpina gear ratios will be a bit of a pain for trials use because you'll need a very large rear sprocket to get first gear slow enough.

[lorenzo]

Yes, Alpina & Sherpa share many features.

Your bike is an Alpina 125 with a Sherpa  Alpina 250 engine.  The tank/seat unit is Alpina. Sherpa tank/seat unit is very similar, but slimmer and with shorter seat.

Front mudguard bracket is a Sherpa item of approximately the same vintage.

Gearbox internal ratios would differ from those of Sherpa originally. Exhaust silencer originally would have been mounted lower inside frame tube (where it wouldn't burn your calf or set fire to your boot leg) on both Sherpa and Alpina.

Change the tank/seat and the gearset and virtually you have a model 80 Sherpa.

Good luck with whatever you do with it.

Edited January 7, 2023 by lorenzo
correction

[stpauls]

Look for a PROPER Sherpa.  Messing about with things is expensive and it will probably be cheaper to buy a genuine, good example of a Sherpa in the long run.

[atitagain]

Thanks for the reply's.

I tend to agree that buying a proper Sherpa is the best route, but since I already have this now I'll see it through with what I have. Half of the outlay is already done.

The exhaust isn't fitted properly and will go behind the frame once I get started on it. 

I will be stripping the engine completely, so if it's just a case of swapping the gears I'll look for a set. Inmotion are selling new gearbox components at the moment, it's just a mater of what model Sherpa to use? probably model 80.

This is the model reference I have found using the engine number. I can't find references to frame numbers alone. I'm inclined not to think it's a 125 with a Sherpa engine, if it were I wouldn't need to change the gears.

85

Alpina 250 (1 st Model)

6638

7/1972

85.000.001 a 85.006.638

Trail

 

Thanks for all your input, 

 

[lorenzo]

You say "I'm inclined not to think it's a 125 with a Sherpa engine".

Yes, you are quite correct. What I meant  to say was you have a 125 Alpina with a 250 Alpina engine - apologies. In basic nitty-gritty essentials, that's a model 80 Sherpa.

I note your bike also has a later swinging arm with trailing tensioner - an improvement over the earlier type.

A long time ago (pre internet & access to online info.) I also bought a 250 Alpina, believing it to be a Sherpa..........

 

Edited January 6, 2023 by lorenzo

[lorenzo]

3 hours ago, stpauls said:

Look for a PROPER Sherpa.  Messing about with things is expensive and it will probably be cheaper to buy a genuine, good example of a Sherpa in the long run.

stpauls - In my experience, doing anything to these old heaps is likely to turn out expensive.

We don't know how much elbow room the o.p. has, pricewise.......

Edited January 6, 2023 by lorenzo

[atitagain]

3 hours ago, lorenzo said:

I note your bike also has a later swinging arm with trailing tensioner - an improvement over the earlier type.

 

 

Hi Lorenzo, that's exactly the type of info I was looking for. I know that many of these have had conversion and update work and I've been out of this for a while so I can't spot it all. Thanks 

[woody]

I'm not overly familiar with Alpinas having never owned one, but I think the earlier M97-99 range of frames are more akin to the series 1 M91/92 Sherpa frames, hence the rear facing tensioner and recessed swingarm spindle

For a gearbox swap you need to check  which mainshaft your M85 engine has, M80 and earlier Sherpas had 13mm diameter where it extends into the clutch with the clutch hub held on a woodruff key. Around 1973/74 the mainshaft was enlarged to 14mm with a splined end and had a larger bearing to take it. The clutch hub was now larger and also splined for the larger mainshaft. This also required a larger ID for the top hat bush behind the hub.

As the M85 Alpina ran from 71-74 later number engines could have the larger mainshaft box, I don't know for a fact but just a possibility bearing in mind they went through about three different frame designs, you just need to know which you have as early and later type shafts aren't compatible

[lorenzo]

atitagain -

Model 85 had a roughly 4-year production run and underwent many detailed changes.

Your gearbox if original is more akin to Sherpa 91/92 than model 80 ; I believe all Alpina mods. 85/97/98/99 had a spline-fitting clutch centre from the outset.

It follows that the mainshaft and layshaft  are the same as Sherpa 91/92, as are the two 5th. gear pinions. (Mainshaft bearing at the clutch end is same as 91/92 at 17mm. i.d.)

The 13mm. /14mm. change that woody mentioned took effect on the other end of the mainshaft, i.e. also affecting the sleeve gear (5th.) and its bushes. Again, if original  splined shaft this won't be an issue.

You could simply replace all the intermediate pinions with a (secondhand ?) set from a Sherpa 91/92, retaining your original mainshaft and layshaft and 5th. gear pinions, if desired.

As far as I know, the selector forks will also interchange.

All of the above - unless someone out there with practical experience of this conversion knows differently, of course........

A gearbox strip will determine what's needed, anyway.

Edited January 7, 2023 by lorenzo

[lorenzo]

atitagain -

As you have a later swing arm, I wonder if you also have a later rear wheel (17mm. spindle, rather than the earlier 15mm.) ?

[atitagain]

It's 15mm 

 

[woody]

13 hours ago, lorenzo said:

 

The 13mm. /14mm. change that woody mentioned took effect on the other end of the mainshaft, i.e. also affecting the sleeve gear (5th.) and its bushes. Again, if original  splined shaft this won't be an issue.

 

 

It was the clutch end I was referring to but I got the sizes wrong as I was trying to remember from some bearing sizes I'd scribbled down ages ago, I think I've given the bearing widths.  The shaft for the clutch hub on the M80 is 15mm, the larger shaft is 17mm. I thought that was introduced later than '72 but It's years since I rebuilt my model 92 which is an early number from '72 so I forget what's in it so possibly yes, 17mm came immediately with the 91/92 models

The Alpina came in 1971 so possibly early numbers had the smaller shaft, I don't know but something to check before buying a Sherpa gearbox

[larry s. k.]

Hi as previous suggested  , big rear sprocket  , , think it’s 56 tooth ,there plentiful ,  upon installing , you get a big surprise ,  able to crawl , and pop wheelies ,  , just a suggestion , on my 121 

[atitagain]

Thanks for the help guys.

Next up, I seem to have just a coil and the 3 wires from the engine. I'm not have lights at this stage and when I do I'll go for an Electrex kit. At this stage I just want to assess a running engine. The coil was in a back with a black block connector, which wire goes where? or a photo if anyone has one.