Ossa Motorcycle Serial Numbers

1. Vintage Ossa Motorcycles

BULTACO MODEL NUMBER REFERENCE LIST. Bultacos should only be referred to by a model number (first couple of digits of the engine number) not by a year. A 1974 Model 120 Pursang may have been sold and titled in 1975. Only the model number will result in a correct identification.YEARS SHOWN ARE ROUGH ESTIMATES AND NOT ALWAYS ACCURATE.

Definitely an earlier (as in pre-green model) 250 barrel. The early 250 barrels had solid fins like yours, the 310 has slots machined into the fins, so visually they are differentFrom the green bikes the 250 also had the slots machined into the fins so look the same as the 310, therefore not distinguishable externally. You can tell from the stud pattern though, as the studs are spaced wider apart on the 310, although I can't remember the measurements of eitherBecause of the stud pattern it isn't possible to put a 310 top end onto 250 crankcases, so another way of checking is from the engine number. If that identifies it as 250 then it can't have a 310 top end, so it has to be 250 - and vice versa. Also, the 250 barrel can't be bored out to 310.This doesn't apply to the Grippers though as both 250 and 310 have same stud patternExample of a 310 barrel in this ebay ad.

Vintage Ossa Motorcycles

Thats the number stamped on the front right eng mount, theres no prefix on that either so cant be sure its right. It doesnt seem to have been tampered with though.I had a look for its ID on the ossa world site before my last post but thought the same as you on the high number.Frame number is 768.241 which seems wrong to me although i`ve nothing to compare it with.If its an after market frame it could be the original number although if its a converted ossa frame will make it wrong and probably the engine too.Wheres JR when you need him? The only thing that I've seen that resembles that frame was around 15 years ago when I bought a TY250 off a bloke near Milton Keynes.He had quite a collection of trials oddities from around that period, one being a cantilever Kawasaki KT250 and the frame and swinging arm was the spit of that in your pics on this and your other thread.He told me it was a Bob Gollner, how true that is I don't know, though Gollner did make a few Ossa frames around '73, though as far I am aware, without the cantilever.