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78 Bultaco Alpina Trials Conversion


gordo
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This model Alpina can be made into a very nice trials bike, very much like the M199 Sherpa T but how good depends on how far you want to go with the conversion.

Yes the tank and seat are obvious.

The airbox and sidecovers arrangement on that Alpina is much wider than the Sherpa T. Replica M198 Sherpa T airboxes and sidecovers are available. An early model Sherpa T or Alpina funnel type air filter would also work but would be a lot louder (induction noise)

The wheel hubs on that model Alpina are Pursang/Frontera type and as such are lots stronger/heavier than Sherpa T hubs.

The triple clamps are Pursang type (to provide more trail in the steering geometry) so to get the trail down to the same as Sherpa T, you will need Sherpa T triple clamps.

The M213 frame has good geometry for trials, but has extra bits that could be cut off to save weight like the rear grab rail.

The motor setup should be fine for trials as it is, but you will need a very big rear sprocket to get first gear slow enough, because the lower gears are taller in the Alpina than on the Sherpa T while 5th is about the same.

If it still has the original Betor shocks, the springs will be a much higher rate than ideal for trials.

Regards

David

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Hi David,

That's a good response. My Alpina based Sherpa must be from that 78 era as the triple clamps were the wider Pursang type with heavier wheels. Had a massive Amal MkII concentric too, too big. I reckon Gordon should hang out for a Sherpa, these were made for trials. If you were keen on the Alpina, and wanted to change the internal gears, you would need the complete set of gears and the final drive gear, one tooth different to the Sherpa. Also, the gearbox casting needs machining away to clear the larger diameter trial gears.

Bye, PeterB.

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Peter, I agree with you, but holding out hasn't worked. The Sherpa's in the states are hard to find. At least the model and condition that I am looking for. My other reason for liking the Alpina is that I would like to run both the vintage hair scrambles and the vintage trials, at Vintage Motorcycle Days in Ohio, this summer. There's enough time between races, that it can be done with some good help in the pits.

Thanks, Gordon

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  • 3 months later...

If you are still looking, go for a model 85 or 99. 85's come up often for sale. I ride a model 85 in trials. I still use the stock tank and seat. You will want the smallest front sprocket you can get. 12 teeth (I think). I'm using a 50 in the rear and wish I had gone a little bigger. I would try a 54 or 56 if I had it to do over again. I've been very happy with this bike. I did ride it in a hare scrambles a couple of years ago with mixed results. I couldn't walk for most of the next week. Too sore......

Hope this helps!

Pete

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Hey Pete Bulpedro. I agree with you about the M85. They are quite OK once geared low enough. The closest Alpina to the Sherpa T of the same vintage.

The M85 was my first Bultaco and I rode it in trials and enduros back in 1976. I remember it cost $450 and in quite sad condition when I bought it in 1975. Here is a picture taken in 1976 after I repainted it.

post-325-1235035569.jpg

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Peter, I agree with you, but holding out hasn't worked. The Sherpa's in the states are hard to find. At least the model and condition that I am looking for. My other reason for liking the Alpina is that I would like to run both the vintage hair scrambles and the vintage trials, at Vintage Motorcycle Days in Ohio, this summer. There's enough time between races, that it can be done with some good help in the pits.

Thanks, Gordon

Sherpas aren't exactly rare. My guess is especially in the NE and NW where trials seemed to be prevalent back in those days.

A really good way to find them is to hand around with modern trials guys (especially the older ones) as they sometime have the old bikes sitting around.

They occasionally pop up on Craigslist. Here in the NW my guess is that I'll see about a dozen Sherpas offered in a year.

If you're in the NE, maybe ask Hugh's if they know of any available.

You do have to work to find the old stuff. People don't just hand them to you... well sometimes they do.

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I know of two sherpas right now that are for sale. Hugh's has one on their webpage. And a fellow around here has one as well (MD). Both are model 199's (I think). One red, one blue. Both are in good shape. Both are also asking about $3000. So I'll pass on that...

-Pete

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