woody

Although I said I don't know about Avgas on your other post in terms of actual use, I do know it contains lead and therefore isn't allowed in trials as only unleaded is allowed (obviously no testing is done so no-one is going to know) However, you really don't need 100 octane fuel for a Sherpa, it runs fine on premium or super fuel. However, I'd avoid E10 due to the increased ethanol which could damage your tank if it's fibreglass (as you have a model M150 it could be an alloy tank) Just stick to premium fuel from the main brands as it contains little to no ethanol Trials engines, from that era especially, are low compression ratio which spend hardly any time on full throttle in comparison to road racing or motocross

The engine is dated in the same way, as from the factory the engine and frame numbers matched, apart from the letter prefix, so your engine is from a 1971/72 bike. There is no difference in performance between this engine and the original engine. Apart from the clutch cover they look the same. There are however a few internal mechanical differences so it is important you give the engine number when ordering parts I don't know about Avgas

The practical advantage of the flanged tubeless rim is that eliminates the possibility of losing air through the spokes which can happen on normal tubeless rims if the seal isn't good (I use silicon sealer instead of a rubber band, the type used on aluminium window frames) However, with some tyres either type can leak from the tyre bead so flangeless doesn't 100% guarantee that a tyre won't deflate slowly over days/weeks Others like them because of appearance which is just personal choice The problem lacing to a Bultaco hub is the length of the spokes on the sprocket side can be a problem. I've seen Fantics with them so it can be done. I think though that they are hard to find now. If you buy a used rim make sure you see it first as they can corrode on the inside so if there is a tyre fitted you won't see it, as outwardly they look fine

There is shortage of IRC, next batch is due at the end of the month. There's a shortage of most tyres at the moment it seems

It's the stroke

They're usually quite tight, helps to warm the piston and it should push out. You can also tap them out but you need to suppoprt the piston so that it doesn't get damaged against the studs and also that lateral force isn't imposed on the rod You can also buy universal pin removal tools which are quite cheap

You won't find the 70 number prefix on the ID listings as it is one of the few number prefixes that doesn't appear for some reason. The Verde 250 is usually a 72 prefix but there were some with 70. The MAR colours disappeared in '76

It's a TR77 Verde which would originally have green frame, tank and guards, not uncommon to find later bikes painted in the MAR colour scheme. If you google Ossa TR77 Verde you'll see images

Yes, it's suitable for that engine

I don't think any record of this will exist, given the small amount made they were probably all assembled around the same time anyway. From what I remember the only variances are bottom fork legs with one or two seals and some not being drilled for pinch bolts on the brake side. A bracket on the down tube on some, triangular alloy head steady on some and a mix of alloy or steel brake and clutch arms. All this can app;y to both 340 and 250 though. As mentioned above some 340 escaped with tapered forks, not sure whether this happened on the 250 as well. Some, maybe all 250 had a small Pursang type weight on the crank, clutch side but still with single row chain, not duplex (mine is like this) Then there are the half dozen that were 6 speed for France - I know this is a big debate as to whether it happened or not, someone has posted on facebook with pictures that they have one. It isn't hard (for a machinist) to adapt a 5 speed case to take the 6 speed cluster, so no reason it couldn't have happened at the factory, or they could have used 250 Frontera 6 speed cases. I have a 199B that has a 5 speed casing modified to take the 6 speed gears

On the model M92, the exhaust does run close to the tank but obviously shouldn't touch. The header pipe slides into the silencer. It may be that it isn't pushed in far enough which is causing it to sit at the wrong angle and slope upwards towards the tank. The silencer has a fixed bracket for attaching to the engine mount so unless that has been altered the silencer can't be mounted incorrectly. From what I can see of the silencer it looks to be the correct one Take the header off, slacken the silencer bolt and refit the header without the rubber and ensure it is pushed fully home into the silencer and see if it sits correctly. If the header is the correct one it should do. If it still touches it's possible the front pipe has been altered or is the wrong one, although it looks the correct one, just painted black, as mentioned above it would be chrome originally. A picture showing the full exhaust would be better. Picture below is a model 92, you can see how close the exhaust is and the angle it should sit at

So we're back to the Talmag again, one trial from many, as other events allow modified bikes so give it a rest banging on about rules you know nothing about and cheating riders. The Talmag has no specials class, all of the bikes should conform to their original spec. Those that don't shouldn't be accepted. That is up to the club. They obviously choose to accept modified bikes and have done for years. No it is not cheating as it is all in the open, everyone can see it, nothing hidden. No-one claims to ride something it isn't. If someone entered on a bike that looked every inch original, claimed it to be original but had hidden or disguised modified parts to gain advantage, then that is cheating. That isn't what happens though is it

I've just been ordering some gaskets from Showe Performance in Stourbridge and noticed they also stock a large selection of of reed petals - may be worth a try if you measure yours, see if they have a match

And that one statement pretty well sums you up. You deliberately isolate an extract from a sentence to comment on, twist it and use it out of context for your own agenda which ultimately leads to repeated accusations of cheating. Repeatedly you say what you want but write as though you're writing on behalf of these ''hundreds of owners of original bikes'' who no longer use them because of the cheating. Prove that. Prove that is why they no longer use them. You actually uinderstand nothing. It's been pointed out several times by people who are out there riding week in week out, why the original bikes are disappearing. AGE. There are several riders in a local club who rode original big bikes, rigids or otherwise, alongside riders on modernised bikes. All mates, week after week, year after year. They stopped in the end because of age and went to lightweight bikes but one or two are now struggling even with those. AGE is the issue but although you know none of these people you'll tell me they put their originals away because of the others cheating AGE is the issue. It's like vintage cars, interest in pre-war and immediate post-war vehicles is dying off along with the generations that had an affinity for them, Later generations have little interest

Do you just interpret what people write as you see fit to suit your own argument. I'm not interested in the Talmag rules as they are for that trial only and I don't and never will ride it, I've no interest in it. Whatever rules are applied to the Talmag have no influence or relevance to what other clubs throughout the country run for their events. And it's not the only event to bring riders from the continent, as you'd know if you rode classic events If it upsets you so much that people are flouting Talmag rules with their bikes, go there and glue youself to the ground at the entrance to section 1 in protest until the organisers haul all bikes back to parc ferme, scrutineer them and put those you think should be there into a specials class. If you believe in and want something, put the effort in and do something about it. You say how hard can it be to note down original bikes? Well go to the Talmag and try it as you're obviously unhappy with the way they do it, go and show them how it should be done and see how easy or hard it is examining almost 300 bikes for anything that might deem them a special As for investing time on this, all you've done is spend 6 years rattling on about it on a forum which doesn't take much time or effort does it. Obviously people are going to think you're trolling and doing it for a wind up when that's all you've done

I asked to see the current rules because riders can only ride to current rules and as I have already explained, there are no current ACU Pre65 rules. It's like accusing football players of cheating because they aren't adhering to the offside rule from the 90s which no longer exists. I'm not interested in the Talmag rules as they are their own rules for that event only. Interest in original 50s and 60s bikes has waned considerably due to the riders that used them back then now being too old to ride them, they're in their 80s at least. Most Pre65 riders, those that ride week in week out, are 50 years old plus, many in their 60s and a good few in their 70s and few have any desire to heave around 250lbs plus of old original bike. Those that do have an interest in them, ride them, enjoy them for what they are and have no problem with current class structure or modified bikes. You'd understand if you rode in the same events they do Most are still ridiing because of the modernised lightweight Bantams and Cubs. Without them they'd have retired. Even modified C15 or B40 are too much in that if they get in trouble they can no longer hold onto it and can get hurt. Anyone with common sense understands this. No-one, as far as I know, has a problem with it and no-one is asking for class revisions. You keep taliking about your rules, amending them etc but what for? Who do you think is going to want them? You're kidding yourself if you think anyone is going to want to impement these ideas. Trials are getting harder and harder top prganise for a variety of reasons, no one wants additional burdens. I'd say if we're lucky we have 10 years maximum left of trials as they currently are. A handful are driven towards winning, most want to just enjoy riding whilst we still can. I help coordinate the Rockshocks national championship and in an attempt to encourage more older twinshock bikes from the early 70s, introduced a class specifically for Pre75 bikes with no later parts allowed which I was happy to vet as it would have been easy. The sections are perfectly suitable as they are and they would have been competing against each other, nothing else. What do you think the take up was? I'll tell you. Average 3 entries per event for that class over the first three events out of 100 plus bikes. Times have changed, even riders who rode those bikes back then are now pushing 70. They want later, lighter and easier to handle bikes so that they can still walk Monday morning. You're living in a dreamland, stop calling people cheats when the bikes they have conform to current rules, not 30 year old rules that are no longer applicable. If you want to resurrect those rules it's been said many times before, lobby one of the clubs to run an event to those rules and if they agree offer to help with scrutineering. If none are interested lobby some like minded riders and form your own club (not hard via AMCA) and run your own event. If you're not prepared to invest any time or effort into doing this why expect others to burden themselves with the extra work of implementing change, when yours, on the surface, is the only voice calling for it

Come on, you're not serious? You're quoting rules for the original Miller series from 30 years ago. The series evolved, the rules changed but regardless, it doesn't exist any more and the ACU do not run a Pre65 series or have a set of Pre65 rules

Which ''real'' ACU rules would these be? Point them out please - if you have the time. And you do realise the ACU don't run a Pre65 championship? And that most of the Pre65 events that happen are non-ACU? Before you continue with your cheat diatribe I suggest you familiarise yourself with the rules of the more regular Pre65 event organisers as if you did you'd understand that modern replica parts are allowed

It's been a long time since I had mine but I think they are the same size as TY250 twinshock. When they made their reed cages they would have used existing petals and at that time the Yamaha was probably the only bike with reeds fitted. The last petals I had in mine were two stage (Boyeson I think) and they were definitely off the shelf items. TY Trials stock the Yamaha reeds

With ruibber, even if the spindle is siezed solid in the inner sleeve it won't affect the swingarm movement up and down, it will still move as normal as the inner and outer sleeves are bonded to the rubber sandwiched inbetween. The outer sleeve rotates around the inner and the rubber twists with it which is the resistance you can feel. They're crap (in my opinion that is) and the bronze/steel bushes work better with no resistance on the swingarm which is what you want, the smoothest and most free swingarm movement

Usually, once the spindle siezes in, it's siezed for good There are two kinds of bushes for the swingarm. The original bronze outers with steel inners, or, the Miller type rubber bush with steel inner and outer. You should be able to tell which you have by looking, the original bushes both have collars on their outer edge. The inner steel bushes touch in the middle so that when the bolts are tightened the frame contacts with the outside face of the inner bushes and pushes them together. This leaves the outer bushes free to revolve around the inners when the swingarm moves as the inners are now fixed in place. You should see the two collars. If you have the rubber bushes there is a spacer between the swingarm and the frame to take up the gap that would normally be filled with the collars of the original type bushes In either set up, the spindle siezes by corrosion in the inner steel bush and usually it's stuck for good and you need to replace the whole bush/spindle assembly If you can't shift it you're going to have to carefully cut through it both sides between the arm and the frame to remove the arm. If you have the original bushes you should then be able to grind or cut off the collar, or what's left of it, from the inner bush on one side and then drift the spindle and inner bushes as one assembly out of the other side, leaving just the outers to then remove If you have the rubber bushes you might have to drill all around the rubber to break it up on both sides (burning with a torch helps but they won't usually melt the rubber, it's so hard - a proper oxy acetylene torch probably will) Once the rubber is broken up you can again drift the spindle out with inner sleeves leaving just the outers to remove Whichever way, it can be a bitch of a job. With working bushes, even if you have a grease nipple (as not all do) it pays to take the arm off and grease the inner bushes and spindle once a year if the bike is used

If that is how your damper rod is assembled then it is correct. The top out spring is the small spring you can see. It doesn't stop the forks topping out if they aren't set correctly with oil but it cushions the impact - you will still hear the metallic bang If you think the forks aren't working correctly drain all of the oil out and then, with the bike on its wheels, push the forks right to the bottom. With no oil you should easily be able to do this in a smooth fashion with no binding. If there is resistance one or both tubes could be bent or there could be an incorrect length spacer on the front wheel which is pulling the bottom of the forks together or pushing them apart, which can also cause binding. Assuming they push to the bottom normally, push them sharply to the bottom and let go. The spring should be strong enough that they rebound quickly and maybe right to the top so that you hear the metallic bang as they top out. It's possible the old springs have lost strength and don't fully extend, if not pull on the bars to check they top out. This will show whether you have full travel up and down on the forks. With the bike standing on its wheels the forks may drop (sag) by maybe 20-25mm under the bike's own weight. Pull up to full extend the fork and to see how much they sag. If it is a lot more than that it's possible your springs are weak so may need some extra preload spacers which is trial and error. It could even have the wrong springs. The fork caps letting air out when you compress the forks also affects the rate at which the forks compress. If they don't vent, the air pressure gives extra preload, if they vent it weakens preload - and can also spew oil out as well as air. Personally I think they are not needed and block the holes off to make them solid caps.

It fits the frame as you can see as it's already in there, but it isn't the right exhaust for that tank/seat unit which is why it's been cut. The model 80 silencer slopes down to the footrest. It also has a small triangular end silencer between the frame and the shock but the bracket for that has been cut off. Just google images for model 27, 49 and 80 and you'll see the similarities and differences

You'd be incredibly lucky to find a 27 frame, Bultaco didn't make many of that model. For use in trials, the frame you have is a better frame with more ground clearance, there is nothing to gain by reverting to a 27 frame if you could find one, other than it being the right type for appearance (just my opnion of course but those early frames with the Y bottom tube layout are quite ugly and clumsy looking)

As mentioned above the frame number is a DIY stamping, not Bultaco, The number isn't even formatted correctly as there should be no 'J', that prefix was introduced around 1975, it should just be a B prefix. It would need to have a frame number related to its age to get a dating certificate to register it on an age related plate, that's probably why it has been stamped up like it is. If you take the paint off the other side of the headstock you might find a trace of the orginal number unless it's been completely ground away Engine stamp is genuine