woody

Why do you think that ? The key is needed otherwise how can the flywheel be positioned in the correct place. The ignition comes pre-set for the flywheel positioned on the key. I'm assuming you have the back plate positioned correctly with the 'T' at the top (coil should be on the left as you look at it) If the flywheel is completely out of position at 180 degrees out it will still produce a spark, but won't fire the engine. If you're not using the key it sounds as though the flywheel wasn't positioned correctly when it wouldn't start but after you altered the timing (assuming by moving the stator on the small allen bolts) it seems likely that when you re-fitted the flywheel you got it somewhere about where it should be so the engine fired. With the electronic ignition, with the flywheel correctly seated on the key you can set the stator in any of the available positions on the back plate and the engine will run on all of them, so altering the timing by moving the stator is a red herring and not the reason it's now running I'd reset the stator to the position it came as, ensure the 'T' on the back plate is at the top and refit the flywheel on the key to give correct timing. It should run no problem like thiis

Plonker is the MAR. Timing can be personal choice but min / max would be 2 - 3.5mm BTDC

The centre gasket is the same for all of the MARs, they just removed some material from the casing surface to accommodate the bigger crank, the stud spacing is the same Your brake cable looks like a MK2 version which is a bit longer than a MK1 cable although it will still work. Rear wheel also looks like a MK2

They are copies of the original style for the M49 and 80 Sherpas, the chrome steel stays are the style fitted to later model Sherpas and as you say, a lot stronger

You don't mention what's wrong with the fork action but when you rebuild, 180cc max of 10W fork oil is a good benchmark, start with 160cc and add a bit as necessary. These old forks won't damp very well if you use thinner weight oil

The fitted wheel looks in good shape so no point changing it for the sake of it really. The older type wheel is a heavy lump of a thing fitted to bikes from 66-73 but it may have varied slightly in design through the model range even though they all look the same, I'm not sure, so finding the correct brake plate may be tricky. Hub diameter, brake shoe width may vary etc. I'd leave that one in myself, I have that type wheel in my own 49

That's a small rear sprocket which will make the gearing very high, standard gearing is 11/46 on a 520 chain. It looks like a later wheel with conical type hub is fitted along with later forks and yokes. Shock top mounts have also been re-positioned slightly lower and forward and gussets added in front of them (not criticism, just observation) You might want to consider re-routing the wiring out of the casing bottom and move it higher to the front as on later bikes as there is always a chance it could get crushed between the bashplate and engine and break with a hard hit on a rock (common on Ossa MAR)

Yes, the engines were removed by the importer and the bikes sold as kits to avoid purchase tax. The frame and engine numbers couldn't match to qualify as a kit so frames and engines were mixed when they were sold which is why they never have matching numbers up to the point purchase tax was abolished in 1973. From then on they were sold as complete bikes so numbers would have matched from new

If you mean the picture on this page, the seat unit isn't located properly and is too high at the front. The flares at the back of the tank should line up to the top of the seat unit. The seat unit you have looks like a new item and they need 'dressing' in places to fit properly. It may not have the recess cut out that sits over the boss at the rear of the tank as the seat unit holds the back of the tank down. You may also have to shave a bit from the inside edge of the panel to clear the air filter hose. If you had the later bike you'd also have to remove material for clearance for the top shock mounts as they only sell one side panel for all series of M49

As you're in the UK the only place I think you will get rings from now in the UK is In Motion but I don't remember what sizes they have left. You may have to try abroad for rings. Join the vintage Ossa group on facebook and ask on there if In Motion can't help

The rod you're holding is a pushrod. There should be two pushrods in the Ossa with a ball bearing inbetween them. If you only have one that's the problem, it's not long enough to engage with the clutch on the other side of the engine. There should also be a seal in the end of the final drive shaft that the pushrod passes through, it might be there but I can't tell from the picture but if the pushrod just falls out it's either not there or so worn it needs replacing as the friction from the seal should stop the pushrod just falling out The standard bore is 72mm with 72.20, 72.40 and 72.60 oversizes, so maybe the 4 you can see is 40 for +40 oversize. You should be able to source rings from somewhere

It's been a long time since I saw chrome as good as that on a Bultaco hub Have the shoes relined with modern material and have them done oversize so that they can be machined down to fit the hub for full contact. Off the shelf shoes like Newfren / EBC have quite thin linings and only a small patch of the shoe actually contacts with the hub. Villiers Services or Safetek can reline your shoes For engine, I've just tried RHT engine paint which is resistant to petrol and gives a nice finish, I got it from ebay. PJ1 used to be a popular paint with a nice finish but petrol melts it faster than boiling water takes butter of a knife now, they've changed something to meet emissions probably. Some people use barbecue paint but I'm not sure how well that resists petrol

I can't see how it can be effective. The middle silencer has a perforated tube and packing around it. The packing can get soaked or clogged with oil and carbon meaning it no longer absorbs the sound, or the packing could have completely disintegrated and have been blown out leaving an empty chamber. Caustic soda won't fix either of these, the only fix is to cut the silencer open and replace the packing after ensuring the holes in the tube aren't blocked. Same for the lower part of the back box which is also perforated tube with packing. The only place it could have any effect is in the rear box of the rear silencer which is all baffles but as these rarely clog (I've never seen a clogged one) I doubt there would be any benefit If the bike is noisy it's the packing that needs renewing

That's the correct size for the trials seat although not the correct cover, the back end was supported by resting on the mudguard. Can't help with the Alpina version, never seen one

My two, one needs rings, the other mains, plus a complete rebuild on a mate's bike hat's been standing for about 30 years and must have had a hard life in the first 10

I'm rebuilding 3 199B engines at the moment. One looks as though it has never been apart before, the pushrod in that is 185mm. The rods in the other two are 187mm....

I'm not aware there was / is an alloy tank for the M49 but Holtworks make an alloy tank for a Pursang which looks the same apart from not having the small flares at the back which line with the seat unit and a seperate breather as they use the cap. It also has twin fuel taps but just blank one off

As Naichuff said, crank,clutch and output shaft. Of the the two larger, one goes on the crank clutch side, the other on the output shaft. The smaller goes on on the mainshaft behind the clutch basket. Each of them sits in a groove in the sleeves that are on each of those shafts There is a blog here that someone did for a model 80 rebuild and he has a model 80 parts list. This will show you where the O rings are on the engine parts diagram as they fit the same on the M92 http://ralphsbultaco.blogspot.com/2014/04/12-download-parts-list.html

Simon Anderson can help with engine parts, his name on here is BOSTIT or you can find him on facebook, John Halfpenny has used spares, he runs the Armstrong Trials website http://www.armstrong-trials.co.uk/

Yes it's possible someone has grafted in the bottom section from a later model, also moved the rear brake pedal to inside the frame. In Motion sell a new seat base unit and seat. This place in Spain do lots of parts for Bultaco including the mudguard stays, mudguards and fuel tank https://www.motosdelabuelo.com/pdf/bultaco.pdf Picture of M49 here, the colour picture is of the last version, the black and white pictures are the first version http://perogress-is-fine.blogspot.com/2014/05/bultaco-sherpa-t-model-49.html

Would going to the pub account for the seat unit being on backwards.... Your frame is confusing, it has the twin tubes under the engine from the last series 49 but has the top shock mount position of the first series 49. Also has the timing cover from the earlier model. Any evidence that the top shock mounts have been altered? Doesn't matter obviously, just curious. Frame number would be interesting but I understand if you don't want to put that out

Sid's Wheels in Stafford will rebuild them if that's what you're looking to have done, he makes his own spokes. He is busy as he has lots of trials riders sending wheels to him. He's done the wheels on my M10 and M27 Sherpas. He can also get hubs / rims anodised, painted, polished, whatever is asked for

The blind bearings in the crankcase, heat the casing and try tapping the housings with a hide or rubber mallet or such like, as this might drop them out, if not use a blind bearing puller The two main bearings usually stay in the crankcase, I'm guessing they didn't as the bush that sits on the crank behind the clutch weight is still in situ ? It looks to be from the picture but not sure. If it is it will hold the bearings onto the crank. These bushes can be very tight sometimes so you may need a normal bearing puller to get them off and pull the bush with them. Without the bush they would normally prise off quite easily Not sure about repairing crankshaft surfaces as that's specialist and I've never had it done. Someone will know. Make sure you use 6205 C3 bearings on the crank, not plain 6205 The detent needs to come out really otherwise reassembling the gearbox can be awkward as it means trying to get the selctor drum in whilst holding the plunger back and out of the way against the spring. They can be tight but it should undo without too much trouble Yes the old race cups need to come out of the headstock as the taper rollers have their own The seat is a push fit into a slot at the front of the fibreglass side panel unit and then held at the rear by two springs from the seat to the frame, there should be two spring hooks on the inside of the frame by the top shock mount

In Motion are closed for Easter, open again Tuesday. With the gearbox, there is one selector that will fit either way around, if wrong 4th and 5th gears can't be selected, it will only go to 3rd, so just test the gears with a dummy build of just the gearbox and selector mechanism to ensure all 5 engage before fully assembling

Which plates, friction or drive. From memory, the friction plates are the same on all Sherpas but the drive plates are different on the M10. possibly the same as a Sherpa N, but don't actually know. In Motion may have some now if any came with the NOS they have recently taken in. Or these people in Spain may be able to help https://www.motosdelabuelo.com/pdf/bultaco.pdf