lorenzo

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About lorenzo

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  • Bike
    (7x) Bultacos 73-81
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    VMCC

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    East Anglia UK
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  1. As I understand it, Sherpa 5-spd.internal ratios were changed to provide a wider spread of ratios, by lowering the intermediate ratios. (Compared to the previous set-up) As top gear remained unchanged and is direct (1:1), higher top speed in 5th. would result only from changing the secondary ratio.
  2. Tom - Glad you've got the rear wheel sorted. Re the front wheel : do stay with the X-3 spoking pattern - both sides. The nearest thing I have to an original, unmolested front wheel is this one : It's not a wheel that I've rebuilt, and as near as I can tell has not been rebuilt by a p.o. (So "original" that I had to replace the tyre a couple of weeks ago, as the old one had completely rotted away !) OK, it's a Pursang - flanged rim, etc. but it uses the same spokes as a Sherpa, and consequently the same spoking pattern. (It's also the same pattern as used in the three mod. 199 wheels I referred to in my last posting.) Hopes this helps.
  3. Tom - I've been waiting for someone/anyone to chime in with all the answers, but it hasn't happened, so here goes......... In response to your original query, it appears from the pics. that these are the correct standard Sherpa hubs and original Akront alloy rims. My 199 parts book lists :- Fr. wheel spokes 18x left hand side 241mm. long 9x right hand side 225mm. long (inners) 9x 227mm. long (outers) 36x nipples (alum. alloy, barrel 6.8mm. dia.) R. wheel spokes 18x right hand side 196mm. long 18x left hand side 176mm. long I've checked some of the genuine Bultaco spokes I have for mod. 159 and mod. 199 wheels and they all conform to these measurements. From the pics. it looks also that the nipples used on your wheels may be undersize - maybe you can confirm the barrel dia. of these ? If you are having a problem with (apparently) short spokes, have you considered that the spokes may be correct, but laced to an incorrect pattern ? How are you measuring your spokes ? Using the above lengths of spokes I don't recall having the problem that you are experiencing but (from memory) none of my wheels are laced like yours; I'm unable to get to any of them at the moment to verify. "Right" and "left" hand above refer to sides of the machine as seen from the rider's view, by the way. Rear rim offset : I've always measured this from the spocket flange on the hub to the outermost edge of the (standard Akront) wheel rim and notes I made for the last three mod. 199 rear wheels I stripped indicate 1 9/16", 1 17/32", and 1 5/8" - take your pick! Front rim offset I can't find at the moment, but would probably be academic, anyway. I usually just centre the rim to the steering axis, as close as poss. Caveat : I'm NOT a wheelbuilder or any sort of expert - someone who is may care to rubbish any or all of the above.
  4. I also spotted the Pursang - but didn't notice the Ossa. Do I qualify for the hoodie (blinkered view) award ?
  5. The pulverised swarf in the bottom of the mag. housing says it all !.........
  6. Your bike is a model 92, which is a Sherpa T 325. This is essentially a "big-bore" version of the Sherpa 250 (model 91) available at the same time. To avoid confusion (in the UK, anyway) Sherpa 350 usually refers to later models/versions. Assuming that your bike was originally supplied through the UK concessionaires, engine and frame serial nos. are probably original, even though they don't match; to avoid purchase tax at the time, bikes were supplied as a "kit" for assembly by the purchaser. Although the bike would have left the factory with matching nos. It would seem that the UK importers were not very particular about serial number matching when it came to selling in this country. My own model 92 has a frame no. quite close to yours, and a non-matching engine no. very close; this bike was supplied new and road-registered in April 73. I have owned it since Jul.75. The tank/seat unit is a Sammy Miller aftermarket replacement for the "Slimline/Kit Campeon" unit supplied as original equipment by the factory. A number of other parts are not original - hardly suprising on a machine this old, but not really a concern where usability is concerned. (With the glaring exception of that open bellmouth on the carb. - you need good air filtration on an off-road bike) Here's an idea of what it looked like 40-odd years ago....... Good luck.!!
  7. Mark - Good luck with the wiring, etc. That's gonna be one pretty bike when it's back together ! Where DID you get that tank/seat unit ? Guessing there's a "lady-of-the-house", I hope that's the spare bedroom...........
  8. Mark - If you need a wiring diagram for any old bike, a good place to start looking is in the maufacturer's OWN literature (if this available), rather than aftermarket manuals which in the interests of sales appeal try to cover a whole range of different models/years/markets, etc. - a task at which they are inevitably doomed to fail.. I've made a scan of the wiring diagram in the original OE instruction manual supplied with UK-market Alpina 85 bikes. There you go :- Incidentally, an identical diagram also appears in Sherpa 91/92 instruction book; it may be of use to UK owners of those models.
  9. Larry - Too much time on your hands ? Doesn't seem ever to be the case for me............... Some of the engine rebuilds "pending" :- Have a nice day Lorenzo
  10. Bondy - ref. the pic. in post #55 - is that a new cylinder liner ? .......Copper head gaskets no longer made, eh ? I'm glad I bought some when they were still available (and possibly less expensive). I think the last time I saw any for sale they were about £20+ each, although Bultaco UK offers an aluminium version at £15.99. Done no actual work to the bikes beyond sorting out what needs to be done, and in what order - organising parts, etc. You know, all the boring stuff.......
  11. bondy - The spacer is #39 in this parts book illustration - the trouble is, if you don't know it's there you remove the top bolt and before you realise it, the spacer rolls away down its custom-made chute (the frame bracket) - never to be seen again....... The part no. is 138.10-119 and it's described as a bush.
  12. scot and bondy - Show me yours and I'll.........well anyway, here's mine - as fitted to my 199B when purchased. Apparently this was the "fix" adopted by Comerfords (the UK importers) on their own team bikes and approved by them for other users. Make sure the distance piece is in place in the 'U' of the frame bracket when refitting the top bolt - it won't tighten properly without it.
  13. I go along with the general consensus that the outer part of the driveside flywheel has been machined down, although I don't know what a model 188 flywheel should look like, either. However, I don't think the holes drilled in it will balance anything - least of all a plain circle flywheel that shouldn't need balancing anyway (i.e. it's not a crankshaft flywheel with bobweights, etc.) - surely the holes are for lockwiring the crank end nut.?..... As already pointed out, the two parts of this flywheel were originally welded together - I have a number of driveside weights in the shed (including a Sherpa 325 item that has what looks suspiciously like a crack through most of the weld); don't recall any signs of balancing on any of them. Disclaimer : my memory's not what it used to be !!
  14. Hey, Larry - "Show and tell time".......(a bit off-topic), but what's happened to your shop FLOOR ? Something interesting caused those cracks ? an earthquake, maybe ? or you been running HD heavywweights in there ?
  15. Steve, I recall a similar topic started last year :- http://www.trialscentral.com/forums/topic/49584-miller-exhaust-replaces-clubfoot-anyone-used-one/ A model 150, if that's the bike in question, would originally have had a clubfoot (apologies if you already know this). Are you trying to save weight ? .....or ?