lorenzo

Don't wanna give you banana skins to slip on, but you sure ? - doesn't sound right to me....... 198 std. front wheel is spoked to a " X3" pattern, i.e. each outer spoke crosses over three inner spokes on the same side of the hub. This applies to both left and right sides of the wheel - long and short spokes alike. As in Woody's second image... Not sure about pattern spokes, but OEM Bultaco spokes came as 18 long spokes (inner and outer) left , 9 short spokes (inner) & 9 short spokes (outer) right , meaning different lengths, by the way.

trum - You don't give your location, but I'm thinking temperate climate ? Some sound advice on offer here... Personally, I would also regard removing the mag. cover now and again to check for moisture, etc. as part of my regular maintenance - even if it's a vented cover (.....and yes, even if it has electronic ignition !......)

I agree with everything Woody says about this bike, and model #92 in general. The tailpipe end appears to be an "Xdusor" spark arrestor, a US aftermarket fitment contemporary with the age of the bike.

+1 for this suggestion - I've also heard in the past of Sherpas using this set-up, although I never got to see one.......

Yes, you can change to l/h shift, if that's your preference - it's a through-shaft, and you should find splines under that cap (hopefully undamaged if the gear lever has always been on the other side). You will need a different/cranked l/h. lever to clear the chain. Less straightforward will be the brake control change to r/h. Later models with r/h. brake have a crossover "Bowden" cable whose outer is anchored between a frame bracket above the pedal and a bracket on the upper face of the swing arm gusset close to the pivot. If your bike doesn't already have these you will need to fabricate your own, or scheme some other way. An existing unused hole in the r/h. frame footrest plate can be used for a bolt-on pedal pivot, and most owners seem to use a steel fabricated pedal in preference to an o.e. style alloy item. My own view is that from a design standpoint this crossover cable is less than ideal - **many riders complain of loss of feel, etc. and this is further aggravated by the use of pattern cables, the o.e. Bultaco item being no longer available.** **Pure hearsay on my part - all my Bults have r/h. shift, but I do also have road bikes...... with l/h.

NO ! Surely he can't mean.......................?? !! .....(Torching my bikes has been suggested more then once by sneering Bultophobes - they just don't appreciate quality !!.)

I wouldn't rely too much on "equivalents" - they frequently turn out to be no such thing (with costly consequences, unfortunately) Should be Champion N57R - well, again it depends on where you look..... N57R is a hard/cold RACING plug, racing denoted by the 'R' suffix - I wouldn't personally see a need for a racing plug if you're not actually racing, just trying to get the bike into some usable state of tune. An old (1987) Champion plugs application list gives : N3C std. or N3G (Gold Palladium type), for Frontera 250 & 370, without year ref. and a recommended gap of .020". (A Clymer manual I have lists Champion N12Y for just about every model Bultaco from 125-370cc, flywheel mag. or electronic, and the same gap recommended for all - .013-.017" - clearly WRONG..........)

"Manual" means the Inmotion manual referrred to earlier ? (and which I don't have). Only manual I can find at the moment containing info. relating specifically to Frontera 250 with Concentric Mk. II - a "Haynes Manual #219 "..........definitely NOT to be trusted, in my opinion........not without reason are these frequently referred to as "Heinous Book of Lies" ............ gives the same figures. However, among my Amal carb. notes for Mk. II Concentric I turned up basic (general, non-manufacturer) specs. for 2- and 4-stroke use, based on the choke/bore dia. and for use at sea-level locations ( and up to 3000ft.) and with recommendations for jetting adjustments (overall reductions/weakening) at higher altitudes. For a 2036 carb. 2-stroke application these basic specs. are : Bore 36mm Needle 2F1 clip pos. 3 Slide cutaway 3 Main jet 360 Needle jet 108 This suggests to me that the "Manual" specs. you have are probably correct, and that the carb. has been re-jetted at some time to suit the p.o.'s location ; I suppose you could do worse than return the carb. to original spec. Whether NOW is a suitable time to do this, you must decide - you could find yourself in the position of having changed so many parts (and the problem persists), that you lose the plot entirely ...........

Paul - Where were you going wrong ? The answer is now glaringly obvious ! Using that printout was your first BIG mistake........ Reading it through several times made my head spin ! (and I'm familiar enough with servicing CB-pointed ignition systems that I don't have to think about it) - I can sympathise with the confusion you were experiencing. To be honest, the last time I did points and timing actually on a Bultaco was some while ago, but the general principles and m.o. apply whatever the set-up - I'm relying on my imperfect memory for the Bultaco specifics here. I can also appreciate that we all have to start somewhere.

"10/12 gauge" - gauge meaning S.W.G. - a BRITISH Standard ? If they are original spokes, I would expect them to be METRIC - 4mm. maybe ? Mic. them to be certain. If you plan to respoke the wheels yourself, I urge you to take as many notes and measurements as poss. before stripping the wheels (and some photos. to make sense of the measurements later, when you have hubs,spokes, nipples, etc. as a heap of bits and have forgotten). Also set wheel spindles in a vice or other firm fixture and spin the wheels to ascertain the amount of buckle/runout of the rims in both planes - if it's excessive it may not pull out - after removing tyres, etc. check also for damage generally, especially to the nipple holes and seatings. There are detailed instructions on how to measure spokes, etc. to be found on the websites of a number of specialist suppliers. OR you could simply get a reputable wheelbuilder to do the whole job for you.........

Sadlotus - Your original post asks "Where am I going wrong?" - well, taking each point in turn, here's a few thoughts of mine :- 1/ "the bike had been sitting for years and the stator and accociated bits were dusty, rusty and neglected. I cleaned everything, new points, condenser, replaced the lighting coil, all seemed to go together easily." Referring to the photo......+1 johnsy's post re the cleaning. Has someone been using the joint face to lever against? Do you have a paper joint to keep the crud out ? Why did you replace the lighting coil ? 2/ "Set the points gap and bought myself a dial guage to set the timing." .......How did you set the timing when fitting EI on the Sherpa ? 3/ "Anyway, decided to check points and timing again. Points gap was a bit wide - reset that." .......How come ? What happened the first time ? In the pic. I don't see any evidence of lube on the moving contact heel, in which case the heel will wear rapidly and REDUCE the gap, not widen it. The felt pad that should lube the cam and control any excess looks rather black, by the way. 4/ "I had marked the timing on the back plate and that hadn't slipped as I thought it might have done" .......If 'slipped' means you expected the stator plate had moved, that's not very likely with three screws securing it...and marking the timing on the backplate is meaningless anyway, as you've altered the timing since - by resetting the points gap... 5/ "timing test light .........workshop manual)........ I can't make it go on/off with the opening of the points" .....Nope , when setting timing I've never been able to myself, or detect any dimming/brightening either, as the test light circuit completes itself by finding another earth. The answer for me is to use a timing/continuity buzzer, which detects the change in resistance when the points open - this allows you to concentrate on looking at the DTI only - far easier than trying to watch both DTI needle and bulb at the same time. Which workshop manual ? 6/ "Everything else works fine - stoplight, headlight, tailight, horn (haha)" ......Assuming you have AC electrics (i.e. direct) how have you wired the stoplight ? Is the stoplamp operated by one or both brakes ? The backfire/banging in the exhaust sounds like an intermittent ignition breakdown is causing unburnt fuel to collect in the system, which is then ignited when normal firing returns. There are many and varied possible causes.... Hope this helps - Lorenzo.

I assume you are referring to this type :- of Spanish-made Monobloc and main jet is #30 in the illustration ? (I have the drawing, but not the corresponding parts list) I acquired a number of these jets "n.o.s" in various sizes along with some other Bultaco parts I bought many years ago, and at the time was unable to find anyone able or willing to identify them. All appeared to have been supplied originally as official Bultaco parts and were packaged and labelled as such; more irritatingly, they are shown in Clymer manuals in similar pics. of carb. and photo stripdown sequence, etc. - and not mentioned in the text ! . Bult 360 - (with apologies for going off-topic a bit) You don't say which Mk. I Concentric - size ? UK replacement, or Spanish original ?

Depends on how much better you would ride with a lightened wallet... Yet another case of believing that every new technological development MUST be an improvement ? Here's a seasoned expert fitting electronic ignition to his Sherpa, in what is described as "a straightforward d.i.y. job which will improve ignition performance and consistency" :- www.youtube.com/watch?v=sJZNao4l0gU (copy & paste) ....and it took only 14 kicks to get it running !

jlpar - I had a root through the residue of my 4-spd. stuff and found a 27t. 3rd. gear pinion but I think it's for a model 11. (It has male dogs as opposed to holes). However, looking through some old Bultaco paperwork, . I found listed : "Part no. 10.11.004 Description : Gear, Mainshaft 27T (low 3rd.) " - not what's listed in the parts book, as you've already discovered, but my limited knowledge of Bultaco part numbering suggests to me that this may be what you require (if that's any help at all). How many teeth are on the mating layshaft pinion ? + 1 with Woody regarding spokes, etc. - (butted stainless would be my choice) - it's all down to how much you want to spend........hopefully, the rims and hubs are salvageable.

The stamping looks genuine to me, and the serial no. is just a few digits earlier than my own 340. Do you know if it's a UK machine i.e. supplied from new, or do you have any history ?

Mike - If it's 25mm. choke/bore diameter, I think that means it's a Spanish-made Amal....... I found this :- http://classicdepartment.com/tienda/index.php?id_product=790&controller=product&id_lang=1 HTH,

Woody - I wish I could have replied earlier; your own posts are invariably knowledgeable and helpful when responding to others in difficulty. I know you have the matter sorted now, but I may be able to offer further info. re the "odd " old bolts you have, if you are still curious:- 9.5mm. dia. is very close to 3/8" imperial, which means they can't possibly be "1/4" whitworth (or 1/4" anything else for that matter, as this refers to the shank diameter). If you arrived at that conclusion using a thread gauge - 20 t.p.i.- then I think your bolts/capscrews are actually 3/"8 BSF - ............unless anyone out there knows differently l (Fettling old Brit. bikes for any length of time soon makes you aware of all these various Imperial standards - on just two bikes in the shed at the moment I have found BSW, BSF, BSC, BA, BSP, UNC, UNF threads - not to mention the odd spurious metric fasteners that shouldn't have been there.....) Happy days !

Lar - Yes, your bike has a standard cylinder head with radial fins, although it looks like a few may have been broken off.......... I don't know where you've been looking for images, but I simply Googled "Model 10 Bultaco" and came up with a numberseveral showing radial fins. Here's an example (I hope) :- http://www.vintagebike.co.uk/pictures/1966-bultaco-sherpa-t-model-10/#.VGzV9zSsUl8 (image #3 shows fin layout clearly) and this will possibly link to many more. HTH

Bondy - The matter of threaded yokes must have passed me by until reading your o.p. - ......but there are pics. all over the internet of course to show this feature on late bikes. My own 340 was just 6 years old when I bought it, but had the 199/199a etc. yokes (bolt and nut clamp). Mind you, it did have the slab-sided alloy tank.

Happyhenry - Well, I think I'd be happy too if my Alpina looked anywhere near as nice........ I assume from the style of tank and mudguards fitted, this is a US import ? Any "E" problems with the tank ? My UK-sourced M85 has a Homerlite alloy tank/seat unit as per the '74/'75 Sherpa T offering, although I must say I prefer the looks of yours. Now, if only I could get my hands on one......... My guards have been replaced long ago by plastic items - not pretty, but the usual practical choice.

I'm sure we'd all love to see some pictures......... (My model 85 hasn't run in 25+ years)

WD40 is virtually useless as penetrating fluid - save it for Water Displacing duties that it was designed for. Get yourself some Plus-Gas formula A or similar and give that a try. Regret, unable to help with the pinion.

Looking at the pic. my immediate thought is that the original frame was probably replaced owing to damage and the number on the replacement was obliterated by grinding and punching it out, possibly to avoid problems with the local registration authority. I don't think this would be too unusual for a bike used off-road, and I think early Bultaco frames were apparently easily bent as well as being heavy (little more than mild steel "gas pipe", according to a frame-builder I knew). Re chrome-plating, this would likely cost as much (or even more) than new bars, and original steel bars got bent even before frames, anyway..... unless someone knows differently, of course. Which gear pinion is damaged - layshaft or mainshaft ? Number of teeth. or part no. ? Good luck with the rebuild.

Very pretty looking Sherpa - well done. However, here's a couple of my observations : front guard looks very tight to the tyre - don't think you'd get very far in mud. Rear chain looks way too slack.

Shirepig - My own experience has been similar to trailie's :" I've got some really old ones to move with a good soak in plus gas then plenty of heat on the nipple with a blow lamp." However, as you haven't posted your location, I cannot be sure that "Plus Gas" (penetrating/dismantling fluid) would be available in your area. I'm also unsure about the availabilty of replacement original nipples as I've not bought any for some time. Good luck with yours - HTH.