midgy Posted September 30, 2022 Report Share Posted September 30, 2022 Hi Guys, Having now fully cleaned up my 198B barrel and cylinder head, the top of the barrel and the underside of the head are stamped 137. It has been over-bored to 73.75 giving 256cc. Do the Bultaco Sherpa gurus suggest my head and barrel came off an older 250 Alpina 137 from 1974/1976? The bike was apparently supplied directly by Comerfords in early 1982 as one of about 110 bikes supplied and sold by them, and was allegedly billed as a 'Vesty Replica' Or perhaps just put together by Bultaco factory using what was just lying around? And presumably over-bored to the max early in its life? Ideas appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
feetupfun Posted October 1, 2022 Report Share Posted October 1, 2022 6 hours ago, midgy said: Hi Guys, Having now fully cleaned up my 198B barrel and cylinder head, the top of the barrel and the underside of the head are stamped 137. It has been over-bored to 73.75 giving 256cc. Do the Bultaco Sherpa gurus suggest my head and barrel came off an older 250 Alpina 137 from 1974/1976? The bike was apparently supplied directly by Comerfords in early 1982 as one of about 110 bikes supplied and sold by them, and was allegedly billed as a 'Vesty Replica' Or perhaps just put together by Bultaco factory using what was just lying around? And presumably over-bored to the max early in its life? Ideas appreciated. Thanks Bultaco cylinders are usually stamped with the model ID of the first model that came with that design. I would have thought however that the 137 had a protruding sleeve cylinder while the Sherpa T 250s went to a soft metal head gasket/flush sleeve before the 198B. My 198 has a flush sleeve and soft metal head gasket. They did do lots of strange stuff to get bikes out the door towards the end and a 137 Alpina type cylinder and head would be fine to use on a 198B. As for the large diameter bore, yes it's fairly common to bore a 238cc motor much bigger than standard to get more grunt rather than because the bore is worn. 2 Quote Link to comment Share on other sites More sharing options...
lorenzo Posted October 1, 2022 Report Share Posted October 1, 2022 3 hours ago, feetupfun said: Bultaco cylinders are usually stamped with the model ID of the first model that came with that design. feetupfun, your 198 cylinder is stamped 165, possibly ? 1 Quote Link to comment Share on other sites More sharing options...
feetupfun Posted October 1, 2022 Report Share Posted October 1, 2022 46 minutes ago, lorenzo said: feetupfun, your 198 cylinder is stamped 165, possibly ? Sorry, I didn't look for stampings when it was apart last, but will next time Quote Link to comment Share on other sites More sharing options...
woody Posted October 1, 2022 Report Share Posted October 1, 2022 Comerfords made a number of Vesty replicas, most were 340 but as far as I know there were two, maybe three 250 conversions as well. They weren't full replicas of his last 340 but had a longer swingarm with pivot point moved forwards. I can't remember if the top shock mounts were moved on these bikes. If yours has the normal square section swingarm it will be a standard B model 1 Quote Link to comment Share on other sites More sharing options...
midgy Posted October 1, 2022 Author Report Share Posted October 1, 2022 Hi Woody, Thanks for the info. I think mine was just a cosmetic type of 'vesty replica', since as far as I can see it is standard B model apart from the engine size having been increased at some stage. It was Pete (Bowker?) at In Motion who said:- "It was one bike of a batch of 110 that was converted/made into a 'Vesty replica' 250 and was sold by Comerfordsinstead of going to a dealer. So it was a standard production model 198B with a few modifications." It was also fitted with a plastic tube type chain guard on the top chain run like a Montesa 348/349 had at the time. Quote Link to comment Share on other sites More sharing options...
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