Ian T

Ok thanks to you both, much appreciated. The length is the same as the M49 spec ones then. I have the remains of the spokes I cut off (in another thread on here I cursed myself for not keeping any samples, lesson learnt...) so I can measure the angles.

Hi lorenzo, thanks for the quick reply. Oddly this is for the front wheel - maybe the rear Pursang spokes on the larger size fit my full-width front hub too.

In my model 49 parts book beside the front wheel spokes it has written in pen, probably by my dad: "use 86-04-003/5" I think this might be because the rim he was using had a different ERD (effective rim diameter) to the standard one. Does anybody happen to know (or can look up) the spec for these part numbers. It should be spokes, and presumably there are two different angles for the inside and outside spokes. Thanks!

Spot on! Thanks so much. That'll be a big help! I may give Sid's wheels a call, see how competitive they are with Central Wheel.

For the older bikes I think zinc plated spokes look more 'period' anyway. I have a Greeves scrambler to rebuild and that will definitely not have stainless ones! Now that you mention it I remember that my parts book is shared with the M27. Could you do me a massive favour and measure the inside length of the longer spokes, and the total length of the middle ones in your picture? Before ordering new spokes I'm trying to get the lengths right, and not sure whether I can trust the parts book! As I cut all my spokes (stupidly!) I can't measure the lengths, but I can estimate the angles.

Problem with the M49 is that some of the spokes are supposed to have extra bends, so it's difficult to source them. Nice work on the plating, it's something I'd like to have a go at. My dad did have a zinc plating kit but unfortunately one of the chemicals leaked and ruined it all!

Who did the paint? Looks like a really good finish. I think I'm going to order spokes in the next day or two. I will use the lengths from the parts book and make a little jig to put the extra bends in. It's a bit of a gamble but not sure what else to do. The other thing that I'm not sure about is the angles for the heads of the spokes. I think the inner brake side ones may be a little more than 90 degrees, maybe 100 or 110. Neat idea actually. Did you bore both bushes in one go? I have some adjustable reamers that should do the job.

A couple of minor updates. First all that gearbox detent. After soaking in penetrating oil and with a little heat from the heatgun it finally agreed to vacate the crankcase... Next I went back to the sleeve gear. Last time I tried to make the bushes I wasn't careful enough with my measurements and turned the bronze down too small. I worked out that it needed to be 18.05mm on the outside, and decided that it would be best to drill the inside of each bush out to only 12mm, and then drill and ream it to match the new mainshaft when it arrives from the US. I will do this with it clamped in the lathe chuck on the sleeve gear's bearing journal to ensure concentricity.

I totally hear you on that, not least because I've been trying to identify bits of other bikes my dad had in bits and it's difficult to tell, unless he happened to write on them with a marker pen what they were. I noted your advice about asking Lynn and I phoned him earlier this week and I'm pleased to say that as we speak a brand new mainshaft is en route to me. Thanks again for mentioning him. Unfortunately he didn't have any spokes, so I'm just going to go with the quoted lengths from the parts book and get Central Wheel to make some (and hope they fit!). There'll be more to report at the weekend - I've been doing other stuff for a week or so, but I'm going to have another crack at the paint. Also I have about 30 things coming from inmotion. I got my order in just before the website went offline - if you phone them (01784 440033) then they will most likely take your order over the phone, which is what they did for me.

Further thinking... I am going to do a trial run at putting a second bend in one of the spokes I have. Possibly I could mill a jig and use the press, to get them nice and even. I have just been digging in the scrap bin and found some bits of spoke. The rear ones are not stainless, and I don't know if they're original, but I have found a few that look a little like the ones in Lorenzo's photo. I can measure the bend in them anyway, unless anyone has some genuine Bultaco ones they can measure. I am also sending the photo to Central Wheel to see if they've ever come across this before.

I have some Bultaco spokes here (not the right ones) and I see it's 4mm diameter at the hub end, and 3.5mm at the thread.

In my book they are 192, 165 and 167. Also it says M3.5 x diameter 4 (rather than the other way around). For the nipple it says M3.6, but maybe this is a typo. Central Wheel have asked me to provide measurements, so I'm not sure what to ask for. They give guidance on how to measure spokes, but who's to say Bultaco used the same method!

Great, thanks. Really I wouldn't expect anything less from those guys anyway. I think that's the decision made then!

From what I can see it will cost me around £200 to have a pair of Bultaco fork legs rechromed/refurbished. And that's assuming they can deal with the taper at the top for the fork yoke (early Sherpa). Or I buy new ones for half that price from inmotion. Are the inmotion ones likely to be of a comparable quality/tolerance? Anyone else bought them and have an opinion? Presumably they are a pattern part and not genuine old Bultaco stock. Thanks!

Wow looks like you really had some work to do! Looking good now though. Funny that you had a near identical paint spraying incident. I definitely learnt a lesson there. I do indeed have some gearbox wear, see below Yes it seems the ones with the double bend (see Lorenzo's post) are the problematic ones. I do have some packets of spokes kicking around, genuine Bultaco ones, but I don't think any of them are the ones I need. Today I managed to use a hybrid of two bearing puller sets to get that last 'blind' layshaft bearing out... Then I got to looking at the mainshaft and sleeve gear, with a view to making new bushes... However I found the wear on the end of the shaft to be uneven to the point of having quite a taper on it. I invoked questionable engineering practices and set about trying to grind the shoulder so that it was consistent for the length of the outer bearing, mindful that the shaft looked hard chromed and there wouldn't be much thickness to play with... ...and ended up going through the chrome. There was virtually nothing left anyway. So that pretty much consigns the shaft to the junk pile. I have two other engines I could use bits from but both have a different (later) type of shaft. One even has needle bearing races for the sleeve gear, so presumably Bultaco did learn. I do have a complete M49 engine which I could strip down, but something tells me the main shaft will be equally worn.

Hi Andy, I asked inmotion about that today on the phone actually and as you say they don't have them. This might be because they have odd bends in them or something. I have written to Central Wheel to see what they might be able to do - I will report back with what I find out. From the parts book: 18 x 195mm, 9 x 165mm, 9 x 167mm (these last 9 described as 'outer spoke' rather than 'spoke', not sure if this means more of a bend), all diameter of "4" which I assume is mm and not 4 gauge. However the Spanish bit shows slightly different info, e.g. "4 x M3,5 x 165". Obviously the 18 longer ones are on the non-brake side. I suppose the outer ones are longer on the brake side as they have to bend round from the other side of the flange, if that makes sense. Like an idiot I didn't measure the spokes or look carefully at them before cutting them all off...

Hi Christian, thanks for the kind words! The chain oiler is pretty neat, but I'm yet to actually try it and see how effective it is. Your bike's looking tidy, always inspirational to be reminded of the finished result I'm aiming for! The paint looks good, but this is something I've stalled on for the minute (deciding which type of paint to use) but hope to get moving with that next week. I have a compressor and spray gun, but had a minor disaster earlier this week when the swingarm fell down after being painted, at which point I got disheartened with the whole project. Took the dog out for a walk and felt better later! I am ordering some parts from inmotion later today. Unfortunately they don't have any of the output shaft bushes in stock but I will see about making some (I have a lathe), if not will try to source elsewhere. Given how worn out the rest of the bearings were I expect the bushes are hammered too. I do have a rod kit brand new in its box but I've never rebuilt a crankshaft before. The crank is probably ok, but close to being on the limit for sideplay in the rod. Another thing to consider is whether I have the old fork uppers replated for £200, or buy new ones from inmotion for £95. On the one hand I want to keep as much of the bike as possible original, but on the other it seems like a no brainer - half the cost for new parts. That's assuming they're as good quality as the original ones.

Ah interesting! Well as it happens the yoke I have is off an M85 because I can't find the original one from this bike. I noticed the two holes but they had been painted over and I assumed they were where it was pinned or something else. But still, even with heating the thing damn near red hot and smacking it via those holes, it still took me the best part of an hour to get the thing off. Can hardly believe it was that difficult. Anyway thanks, that was vital info. I think I'd have tried again to grind the thing off if that hadn't worked.

Ah of course! Why didn't I think of that? The frame tube has a threaded hole on top, behind the headstock, so that's how you'd fill up the frame. Still no idea what that's for.

Also the cylinder head nuts on the M49

Ok so I decided to at least try to act like an engineer and broke out the thread gauge. Seems the MB reference is a fine pitch, 8MB being M8 x 1.00mm. Lorenzo - I found a bearing separator like you linked to, worked a treat. I'm now preparing the frame for some paint, and noticed something that looks non-standard... There's a little tap mounted there, and at the top between the headstock and the petrol tank mount there's a drilled and threaded hole. I can't imagine - on a two stroke - why you'd want to store oil in the frame, assuming that's what it is. The only possible idea I had was that it might be convenient to keep oil somewhere for when refuelling on long distance trials. I also found this in the box of parts, same idea perhaps: The Sammy Miller sticker may or may not be original! Another interesting thing to note is that the (presumably genuine) Sammy Miller top yoke has 5/16 BSF bolts for the handlebar clamps. I am guessing they weren't specifically aimed at Bultaco owners? And lastly, the swinging arm spindle appears to be half inch, with a 1/2 BSF thread on each end. I thought standard was 12mm. Maybe dad had some play so he reamed it out to half inch and fitted a bigger spindle?

Thanks, useful tricks there. I also need to get the bearing race of the bottom yoke, as I'm switching to tapered bearings. Seems none of these things want to play nicely! Also I was looking at the nuts and bolts in the parts book. It uses 'MA' and 'MB' - do these denote different thread pitches? So far it seems to me that 6MA is M6 x 1mm, and 8MA is M8 x 1.25mm. Is that right?

One of the blind bearings tapped out like that, the other didn't. I think I will wait until I have a puller. As for the detent, applied a fair bit of heat and it won't budge. I could try getting an impact gun on it.

Thanks woody, all good info, cheers for taking the time to explain all that. There was a bush on the crank that took some persuasion to get off. The two main bearings are now the only things left. The Haynes manual - which I'm not fully trusting - did say the main bearings should stay on the crank as it comes out. Noted on the C3 rating - I saw this on inmotion and will make sure I buy the correct ones. The seat does have the bracket at the front, and at the back it has two pegs which I am assuming the springs located on. Tomorrow I'll have a go at those bearings and see how I get on.

Hi Andy, I was wondering the same thing re the seat. Not sure yet, need to work that out, but it's some way down the list of priorities. I will get there though - the fibreglass definitely needs some work. Unfortunately I don't know much (yet) about Bultacos. I've been cleaning a few bits up, and also disassembled the engine... The engine took a bit of work, and didn't quite come apart as expected. The layshaft was stuck in the right-hand case and all the gears came loose instead of staying in the lefthand case. Then when I came to remove the crankshaft it practically fell out of the bearing (which remained in the LH case). There's some evidence that the crankshaft had slipped inside the bearing - the bearing being completely worn-out. Talking of worn out, just about every bearing in there is knackered. The old man must've got some use out of this thing. I have a few questions at this point: - The bearings that are pressed into blind recesses in the case - how to get them out? Presumably heat plus a special tool to hook them out? - Are there any tricks for removing the two main bearings from the RH side of the crankshaft? - I don't think the LH side of the crankshaft is necessarily toast (I tried a new 6205 bearing on it and there's interference) but if it turns out a rebuild is needed, does anyone here do that as a service? - The 'detent' in the LH case seems seized in there - does it have to come out, or could I just leave it there? I'm wary of going too mad with the blowtorch. The frame also needs some attention shortly. I want to switch to a tapered headstock bearing arrangement as sold by inmotion. Does this first require the old ball race cups in the headstock to be tapped out? As I am about to prep the frame for painting it would make sense to do this beforehand. Thanks in advance for any help, it'll be greatly appreciated!