woody

I don't know. Not sure if the crank is suitable for 2 bearings so I can't give you a definitive answer. However, I can't see any obvious reason why a later holder without the deeper insert couldn't be used. But I could be missing the obvious... By the way, you only use a gasket or an O ring, depending on which holder you have. Not both together.

The 175 used a 250 frame, it's basically a 250 bike sleeved down to 175. Easy to convert back to 250 with an overbore. Yes the wheelbase is correct because the 250 frames between '76 and '78 differed from the 325. They had a bend in the front tube just under the headstock and had shorter forks. They handle well and turn a bit quicker than the 325. From '78, they went back to using the same frame for the 250 as the 325. 199b - If you use an alloy tank from the model 198 you will also need the corresponding seat. That shape tank had a different slope at the rear from the plastic tank, so the front of the seat has to match. But they won't look right on the 340 at all. They only came with the plastic tank or a one-off UK alloy tank which was a squarer, different shape which is not the same shape as the plastic tank (or therefore, the alloy tank that is currently made in Spain) Shedworks do a fibreglass ethanol proof tank the same shape as the plastic tank but about 1" slimmer. Either in blue gelcoat finish or plain for painting, both options allow the use of decals (you're right, decals won't stick to the plastic tank) The exhaust looks standard. The weld you've pictured is normal. The 199b airbox is unique to the b model and works fine. The 199 and 199a used a different airbox which was considered restrictive and the factory riders used to replace it with the older type. Someone seems to have done the same to your bike for some reason. If ultimate performance isn't needed, a pair of steel bodied Betor shocks should do the job as they work reasonably well and are a reasonable price. If the bike runs fine I wouldn't waste money on a new carb, especially if you're not using it in serious competition. If you do want to fit one, a 28mm OKO (not the powerjet version) works well. I have one on my 340 and it only needed a slight decrease on the pilot jet to a 39 from stock settings. They're about £60 off ebay. I only mentioned not a powerjet version as mine is the normal carb, so I don't have jetting for a powerjet as they are different I think.

Sounds like you have spent time on sorting the bike and have most/all of areas I mentioned covered already. The way you described the engine response initially is how they are as standard, pretty flat. It takes a while to get the flywheel mass turning and then just as you want to power off it gets going. So the next thing to try is run it without the weight altogether.It will run fine without the weight fitted and you won't lose any tractability without it, but it should improve pick up again. Try advancing the ignition a little. I can't remember what the static setting is for the TY but you can advance it to 3 or 3.5mm BTDC which,along with removing the weight should help it pick up quicker. Something to note though, is that if you fit electronic ignition, they have a built in power curve which runs the ignition slightly retarded for the initial response, advancing as revs increase to give a more controlled and progressive throttle response which will keep the pick up on the lazier side. Not really needed on the TY250 as they aren't a sharp engine. More useful on snappier engines. It will probably pick up quicker on points, with it advanced as suggested. If you still want to try the 320 route after all else has failed, If I was doing it I'd look for a complete engine to convert. Once you've opened up the crankcases for the larger sleeve, I'm not sure how well it will work as a 250 again if you refitted the 250 top end if it turned out you didn't like the 320. There would be space around the bottom of the liner due to the smaller ID of the original. This may affect crankcase compression or transfer of fuel up through the transfer ports. I'm guessing, you'd need to check this out from someone with better knowledge on that than mine. Loads of TYs have been broken, getting hold of an engine shouldn't be too hard I wouldn't have thought. The Yam is a relatively short bike anyway and they are a bit light on the front on climbs, the 320 exaggerates this even more with its increased torque. The fact that the steering was steepened when they did the Majesty copy would account for the even shorter wheelbase you measured. Majesties didn't have their steering altered (generally, some did) Also, what did they do with the footrest position. If this was moved, it may also exaggerate the light front end. If you fit the mono forks, you will move the front wheel forward as they're leading axle and this will increase wheelbase further, now that you have fitted extensions to the swingarm. You may want to try a standard swingarm again when you have fitted them. The extensions will help stop the bike lifting on climbs but the addition of mono forks may not help the steering. It's all trial and error once you start modifying frames and footrest positions etc.

Sorry, forgot - the allen bolt that holds the fork leg on sounds as though it still has the original washers, as they were fitted with a flat washer as a seal and a locking washer. I just clean and inspect the mating surface of the leg to ensure it hasn't scored or whatever and fit a new fibre or copper sealing washer. Tighten with an air ratchet if you have one, using either of the methods in earlier post to hold the damper rod.

Your springs are the correct length - 17" I've used an impact driver on drain plugs, it's worked without me using too much force. The screws in the bottom of the caps are some kind of valve to prevent fork pump up due to air pressure. You should see a small hole in the top of the fork cap somewhere which I believe was to let air out and prevent pressurising. I've never understood how these are supposed to work and on Bultacos in particular have only ever served the purpose of squirting oil in my face when the forks compressed. I've always sealed up the hole and never noticed any problem of pressurising in the forks.

If you've tried the usual sources, you've probably overlooked John Collins at JC Motorcycles, Port Talbot. He has used Bultaco parts. You could also try Wakefield Offroad as they have broken lots of trials bikes over the years.

They have the deep insert for the engines that have only a single main bearing on the clutch side

The problem with the 320 is that there are good and bad. Even if you try one, with no prior experience of riding them you won't really know which you're trying. They are infinitely tuneable to make them soft, sharp etc. and it is possible to get the 320 to rev clean out (I had one but it was like it when I bought it) But, the difficulty is getting it how you want it as they do seem to finicky in set up, especially carburation. I've had three and they were all different and only one would rev until it screamed, the others flattened off before top revs. I've heard of other people complain of the same problem, yet I've also ridden others that have hit top revs. This is what I mean by finicky to set up to run as they should. On the last two I had, I did wonder if the electronic ignition was stopping them hitting top revs, but never put them back onto points to check. When I bought the one mentioned above it was on points and screamed, but after we rebuilt it, it never revved out properly What you have to consider is what type of trials are you riding it in. There are no classic club trials that need the power of a 320, a standard TY175 is usually enough for 99% of classic club trial sections and more often than not, 100%. The 320 was introduced as an expert bike for national standard riders who were riding big sections. You'll encounter nothing like that in a classic club trial. They can be very good, but they are pokey - do you need that power. Is it going to get you in trouble. Money spent on the 320 conversion and then the time to get it running right, is probably better spent on sorting other areas on your 250. Decent shocks (steel body falcons are by far the best value for money), good tyres, brakes shoes relined with softer material for efficient brakes, front fork set up and get the 250 motor running properly. You'll have a bike that works well and more than enough for classic club events.

I'll check spring length tomorrow. From memory I think they come to just where the fork cap threads are in the tube and they had one spacer as standard. Oil is 180cc and 10W works fine. As you're dismantling completely check the fibre 'piston ring' on the bush at the top of the damper rod (earlier forks didn't have one but yours should I think, depends on what parts they used) If this is worn it will let oil past which reduces damping effect. As a guide, see how loose the damper rod is in the stanchion before you remove it. Push it up into the stanchion and with the stanchion upright, let it go. If it drops back out with no resistance, the fibre ring is probably worn. You can replace these with PTFE card, available from ebay as a sheet in varying thickness (same as is used in Rockshocks) Just measure the thickness of the existing ring. Cut strips from the card using the original as patterns for length and renew. Refit the damper rod (it will be a tighter fit this time and need a bit of persuasion) then repeat the 'test' from before by pushing the damper rod into the stanchion and then letting it go. It should now hold its position due to the tighter fitting bush, or at worst, lower itself slowly instead of the previous 'freefall'. A bit fiddly but worth it as the damping qualities of older forks need all the help they can get after 40 years use and wear, although the Ossa had the best from that era (in my opinion) EDIT: Is the difficulty to remove the allen bolt in the bottom of the fork or the drain plug? If the allen bolt that holds the fork bottom onto the tube, fit the spring and some extra spacers and replace the fork cap, the extra spacers will preload the spring more as this sits on the top of the damper rod. When you turn the allen bolt, if it is tight it will just spin the damper rod inside the fork, as it is the damper rod it screws into. The extra preload on the rod should stop it from turning. However, if it is really tight, it will need shocking free and that is best done with an air ratchet. The other way is remove the spring. The damper rod has a slot in the top of it which will take a blade, such as a flat blade screwdriver blade. Push the fork leg up as far as it will go and shine a pencil torch down inside the stanchion, you should see the top of the damper rod and see the slots (some rods don't have them but Ossas usually do) Check that the splash guard isn't obscuring the top of the damper rod. This is a U shaped piece of metal that is a press fit into the bottom of the spring and comes out still in situ. If it ihas lost its tension it may have dropped out of the spring and be sitting on top of the damper rod. It will just slide out if you tip the leg up. The slot in the damper rod is thin, too thin for most screwdriver sized blades. Dealers had a special tool. You can grind a bade and lengthen it, or make something suitable that will run down inside the fork tube and locate in the slot, this will hold the damper rod and enable the allen bolt to be undone. If it hasn't been apart for some time, it will probably be tight.

Any of the barrels can be used, it doesn't matter which If I was having it done I'd give the barrel and new 360 piston to PJ Motorcycle Engineers in Wolverhamption who will make and fit a new liner. It needs a new liner as the original hasn't enough thickness to be bored to 80mm. The 320 isn't ported any differently from the 250. I'd only use a genuine Yam piston. Patterns can be poor quality and will rattle soon after fitting. Yams don't rattle if bored properly and run in properly when using original pistons. The DT piston is better as it has windows cut into the inlet skirt rather than the YZ which has an arch cut out of the skirt. Windows give a better bearing surface and longer life to the piston. You can use a DT400 piston which will give 340cc instead of 325cc. No difference in performance, they both pull like a train. If you're buying from USA remember postage costs and you may have to pay import/customs duty. The latter is the luck of the draw. If you have to pay it you'll be close to £150.00 anyway. If buying from UK make sure it is a genuine Yam piston. For genuine pistons in UK try Moto Ward, Moto Link, who both specialise in old YZ parts. Or Nigel Birkett who may still have standard size pistons Can't help you with what to do with the head as I haven't a clue, but with 10mm difference in the bore size, the original 250 obviously won't work. The 2mm spacer is to restore the piston/port timing as the 360 motor uses a 70mm stroke whereas the 250 is 65mm. Therefore the 250 piston is a different height from the 360/400 The crankcase mouth needs opening up to accomodate the bigger liner which has a much bigger OD with the 320 liner. This can be done with the engine built using a flap wheel (how Shirt did it apparently) but obviously you have to protect the bottom end from swarf etc. Jetting is similar to the 250 but you have to go bigger on the main jet from memory. However, be warned, that they are a pig to jet and get to run properly and very difficult to make rev out cleanly. They have loads of bottom end torque but don't like to rev out. Ask yourself is it worth the effort and cost for what gain? I'd estimate you're looking at around £500-£600 to do all this. You may be better off speaking to Nigel Birkett and asking him if he can port your 250 barrel. He never used the 320, just a 250. With a properly ported barrel and a lighter flywheel weight, the 250 will go very well. Even just removing the weight altogether and nothing else makes a difference. Which is something else to consider. The 320 had a custom made weight to keep it tractable, a fair bit bigger than the heaviest of the standard weights fitted to the 250 motors. It's unlikely you'll find one of these now and the 320 with a lighter weight can be a bit lively.

Willie, I agree with what you say in principle, but Yorkshire Classic don't allow those forks into Pre65, only Pre70. As far as I know, the Pre65 Scottish won't accept them either, but their criteria for forks is subjective and vague at best. So someone, at sometime, made the decision not to accept them as Pre65. Difficult to change this view now I think. Now my point is, that if those forks were definitely available to the public before 1965, and the whole Pre65 ethos for eligibility is around maintaining period appearance of components (but fails in actual fact) what's wrong with a pair of Ossa or Yamaha forks which aren't leading axle and have the same appearance as the aforementioned. Or Montesa yokes that are virtually identical to modern billet. This is where I think the criteria achieves nothing and contradicts itself.

Yes, MK1.5 is the MK1 but with the MK2 choke device. As far as I know, the internal workings of the MK1 and MK1.5 is the same. I've heard it said that the pilot system differs but from what I now and remember of the MK1.5 that I had, they are the same, someone with more knowledge will no doubt clarify. The jets, slide, needle etc are common to both. The MK2 uses the same jets as the MK1 but has a different slide, so not interchangeable. Not sure about the needles, can't remember. I think it has a different, more efficient pilot circuit than the MK1, but again, someone with more knowledge will clarify.

Derek - my comment is still there, it's on page 1 of this topic. But it needs to be taken in the context it was written, and that was in reference to a comment from 340Villiers and people 'breaching' current rules, which have been in their current format for, at a guess, about 10 years or so. Not whatever rules you wrote back in '79 for your trials. Current eligibility rules allow the use of modern components as long as they are either hidden inside period components or machined to resemble the originals. They rule out the use of '70s / 80s twinshock parts such as wheels or yokes, because they aren't Pre65. Neither are newly machined parts Pre65 but the reasoning is they resemble the originals, so they are allowed, the concept being that they keep the machine within the spirit of Pre65 and resembling the original: ie: the silhouette . Except that they don't as a current Bantam, Cub, Ariel etc bears no resemblance at all to a 1964 bike. Bantams can use 4 speed motors when they differ visually from 3 speed. One club allows Cubs to use Dellorto carbs but nothing else can. So as far as I can see, the rules do not achieve what they are supposed to achieve, which is keeping the machines looking period. They're nothing like, hence my comment that you picked up on. It's a fairly straighforward view and one that is hard to dispute and I raise it because I get sick of people calling others 'cheats' for having 'non-elligible' parts. My own BSA has a Faber MK3 frame, it has Alan Whitton Yokes, Ossa forks, a Grimeca front hub and a Sherpa rear hub. The Ossa fork legs look the same as any other alloy fork legs that are allowed, but they aren't. The front hub looks like a Greeves or Rickman conical hub, but it's not allowed. I guarantee not many people would recognise what the rear hub is and it looks very similar to a modern billet hub. All 'silhouette' as they say - not that I built it to try and comply with anyone's rules, it's from parts I had lying in the shed, but silhouette nontheless. However, it's a 'fiddle' or 'cheat' bike according to some. The fact is it is far less 'fiddle' or effective in competition than many elligible machines. So yes, with those facts, I stand by my view that eligibility rules are flawed, cost people a lot of money and do not achieve the one thing they were supposed to - keeping a machine looking period. In the case of Scotland, it can cost a lot of money for no purpose, building a competitive bike that complies but never getting an entry. I still can't see what the issue is with modified machines, and modified is modified regardless of whether the parts used are deemed acceptable or not. If people want trials for standard machines just run them... !!??

ACU link http://www.acu.org.uk/Uploaded/1/Documents/Trials%20Results/2014%20TRADITIONAL%20CHAMP%20REGS.pdf

First round is the Phil King at Colchester on Feb 2nd I just found the series regs on the ACU website which has the new classes. On the harder route, the new class G is for machines with air-cooled engines, that's the only criteria. So in other words, that covers twinshocks, highly modified twinshocks, monos with two shocks fitted or monos, including the Scorpa SY 4T monos. Seems reasonable to me, in view of what's happening with bikes. Personally I couldn't care a toss about the classes, I just want to ride my Bultaco or Ossa in trials I enjoy, so it will change nothing for me, unless they make them too tight, as I can see the majority of the entry being modern bikes.

I'd have said with that background you'd be fine with the Normandales. They aren't as difficult as a British Championship or Centre championship from the late twinshock era. Up until now, I've always ridden the twinshock class, so that's been the harder route. Pre65 and over 50 riders on modern bikes rode easier routes through some sections when a section was marked out with 2 routes. Because of the class changes this year, I don't know if the hard route will now be made harder, or whether the trials will stay the same as they always have been. I've seen no information on what the purpose of the class changes is. I only rode a couple of rounds last year for various reasons, so I don't know if there was some sort of discontent with the trials themselves. I haven't heard anything other than some murmurs of discontent about how some bikes are being modified. I'm going to enter the hard route for the first event, see how it goes and take it from there. If they're just going to tighten evreything up needing clutch / brake everywhere, which will encourage stop/hop riding on the 'more capable' bikes, which will inevitably go unpenalised, then that will be the end of it for me. I can buy a GasGas if I want to ride trials like that. I don't.

Both have roadwork Both have classes for twinshocks Miller series is on about the same level of severity as an average classic club trial Normandales are a step up from Miller in level of difficulty but can vary from event to event. The easiest is harder than the hardest Miller round. Normandales have a class change this year and the twinshock class has been moved from the harder to the easier of two routes, where two routes are used. Some trials may only be one route, but most now have a percentage of sections with two routes. The easy route is still harder than the Miller series. Normandale still has a twinshock class on the harder route but it is a class for twinshocks AND air-cooled monos now. I can only assume this has happened because of the more radically modified twinshocks that are appearing (not many but a sign of things to come?) and air-cooled monos being fitted with twinshocks. If riders are looking to win a championship, they will enter the hard route. If they are doing it on a bike that no longer resembles the original twinshocker or it is modified mono, maybe the ACU have decided to lump them all in one class with monos..?? An attempt to discourage it or just coincidence. Who knows. Of course, this doesn't stop someone entering the twinshock class on the easier route on a similarly modified bike, but I guess the thinking may be that they are less likely to bother going to the trouble and expense of making such modifications and just use a standard twinshock. Or maybe there was no such thinking at all. Who knows. I only know about the class changes because they are on the entry form for the first round. I've seen nothing on the ACU website about it. Doesn't mean it isn't on there but I haven't seen it. There are moves to organise and run some twinshock only trials this year, in different locations. These are seperate from the above two series. A sort of pilot to assess interest with the intention of running a series next year, no roadwork. Discussions are ongoing, logistics etc. whether there would be any interest, a set of sensible rules needs to be drafted, with the intention of 'discouraging' radically altered machines. It would be nice to see a series again like the old Sebac / Falcon series of the early 90s before it got screwed by making it one route. Entries of over 100 at virtually every round and a nice variety of pre65 and twinshock bikes. I used to enjoy that series, happy days.

Look forward to seeing the Italjet out. Someone rides one in the Perce Simon Miller round every year, a nice one too. Be good to see another one. I didn't know anything about the class changes to the Normandales until I got the regs for the Phil King. There's a twinshock class on both the hard and easy route now although on the hard route, the twinshocks and air-cooled monos are in the same class.

I think it is a factory 250 engine.

Normal circumstances ?? I've lost track of what they are these days I think conversations go along the lines of " I want to ride twinshock trials, so I'm going to buy an air-cooled mono and stick 2 shocks on it, or I'm going to buy a twinshock and then modify it to such an extent that it bears no resemblance to the bike it started out as". Because, " I need a highly modified twinshock because modern classic trials are so difficult that a standard twinshock can't clean the sections" Of the latter, someone point me in the direction of the classic trial that has sections as hard as the '70s Superstars trial that has been posted on here, or a typical early 80s British championship round. Anyway Dabster - when are you going to notice the hydraulic clutch on that SWM..

And the Scorpa gear lever... I thought the engine in that bike was one of the factory six speed versions, not a 175/200.

Late 70s, early 80s

Yes, forgot to mention it's a powerjet but I've no idea what it's supposed to mean or how it works. I just ordered it and I'll play it by ear when I fit it. Not sure if the jetting will be different. The spare jet they mention they'll supply seems bigger than the usual 112 that other OKOs I've had come with. The OKO carbs I have, some have an inlet banjo (ie: fitting to take a pipe the same size diameter as the overflow pipes or the powerjet pipe) in the top of the inlet stub of the carb. No idea what this is supposed to do or be connected to, I blank it off. If you don't it will just suck air in. Others I've had don't have this. They all seem to work the same..? The Armstrong airfilter and hose is one assembly but you can't get them anymore. Because I fitted a non-standard airbox I didn't bother to find out what they use instead now - or more likely I've forgotten.... Bostit will know but not sure how often he's on here. I'll send him a text and ask him to reply.

I agree, emptying the tank is the best option - I just forget... I may learn the hard way one day...

I've just bought an OKO off ebay for a Bultaco from a seller called extremeimport who is in Peterborough. Should have it by Tuesday next week, postage was free, cost was £59. The OKO I fitted on my 320 performed pretty well out of the box, as they seem to on all bikes I've tried them on. In general, only slight changes to pilot or main jet have been needed and maybe moving the needle. I've never fitted a different needle or needle jet. I've got one on my 310 Ossa and 340 Sherpa and both run very well (26mm and 28mm respectively) I no longer have the jet sizes I used on the Armstrong unfortunately, I can only guess at 118 main (normally they come with 112 as standard) and something like a 40 pilot. The jets are quite cheap for a box of 12, so worth buying a range of pilot and mains. I'm not convinced that there is any worthwhile performance difference between the various carbs. I think when people fit an OKO and feel a difference, it's more likely that they feel the difference between a new carb and an old worn out original and the same difference would be apparent with a correctly jetted, new Dellorto, Mikuni or Amal. My other 340 Sherpa has a Dellorto fitted and it runs every bit as well as the OKO bike. When I had Armstrongs new, they ran absolutely fine on the Amals which were obviously new as well. I can honestly say that there was no noticeable difference between how the 320 I recently rebuilt with the OKO ran and how I remember my old 320 with the Amal. I thought about buying another Amal as there would be no problem jetting it. The only thing that stopped me putting a new Amal on the rebuild was the price of £140 plus which is a lot more than an OKO and a fair bit more than a Dellorto - and the fact that I had an OKO already. Taking the above into account, if you're prepared to play with the jetting, the cost of the OKO makes it the more favourable option for a new carb. Edit: - forgot to mention that Bostit has an OKO on his 320 with a standard airbox. I can't help with knowledge of the fit of the OKO with standard airbox as I had the alloy one made to use a different filter and hose.