Bultaco Sherpa What To Do?

[Mrapocalypse]

157 is listed as Sherpa T 125 on one list as Graham said. My 4 other lists don't include that # at all.

Have you measured the bore?

If its the later 125 short-stroke engine it should have 54.2mm bore & central exhaust port, but if its the earlier long-stroke 125 engine it would be 51.5mm bore ( for standard bores)

Hi,

Nope, definitely a 250. 72.6 bore, 71.8 Piston.

.

I.

[Mrapocalypse]

If you get a 10 tooth sprocket for the front you can use a much smaller rear to get the same gearing.
You should be able to work out what gearbox it is by putting it in first gear and measuring the ratio between sprocket and clutch. There are specs available for the gear ratios of Alpinas and Sherpa Ts gearboxes

Well, I don't know if this is right but it is about 3.4:1

I just marked the main shaft and the output shaft and it did three and a fair bit turns for every one of the output.

I looked in the book I have and a Sherpa primary ratio, whatever that is, should be 2.37. Which means my testing method is off or this is one seriously low gearbox.

The book says it should have a rear sprocket with 52 teeth and the front should be 14…. mine has… 52 and 13….

The primary drive sprockets are 16 and 38 teeth, which fits heaps of models.

Also, I just read that single row primary chains are by no means uncommon in Sherpa's.

After a bi of photo analysis, I have discerned that the second or third serial number is an "8". I'm also seeing a feint 9 or maybe a 5 so that's leaning me to Sherpa…..

Thoughts…

I.

[Mrapocalypse]

Here's the link http://sherpamanuelsoler.blogspot.com.au

That sir is a very clever deduction.

Thank you a great deal.

I.

[Mrapocalypse]

OK so this is the final chapter.
Years ago, I was bidding on a bike on ebay.
I saved the images.

Heres a dissasembled 158 motor. The guy finished the auction early otherwise I would have bought it.

Notice single row chain


And 157 stamped on the head. I never put together until just then.


Nice clear Serial.




I reckon that's got to be it.

What's with going to such great lengths grinding off a serial number on a Bully tho???? I dread to think.

Thanks to all who contributed.

I,