woody

Yep, should run no problem, one of our lot has that combination on his 320 Majesty and it runs fine. I had some lugs welded onto my WES middle box to bolt the heat shield on. You can hold it on with a couple of good strong cable ties though. I've also done this without problem, they don't melt.

No, that's a one off pipe made by someone for Ian

depends on the piston used, there are various options and I think it's correct that not all need a spacer as some have the same pin to crown height on the piston as the 175.

Sorry, no idea what the number 18 signifies. Perhaps Nigel Birkett may know if some were stamped for any reason, he's your man for anything Yamaha. Piston kits are generally a reasonable price, but if the barrell needs replating then that costs a bit. Head gasket is pricey. The TYZ shouldn't rattle so something is worn but obviously impossible to say what, could be piston, small end, big end or all three. It's an amazing motor the TYZ, they really will take some abuse. My Birkett framed TYZ suffered a heat seizure on the road in the SSDT after a blown head gasket let all the coolant out. It was locked solid and very, very hot. After it cooled down I filled it back up with water, managed to free it off and kicked it up. It had no compression so I guessed the rings were stuck but it started and got me back to Fort William. Fitted a new head gasket and managaed to get another couple of days in before I retired as it was still losing coolant and I didn't want to damage it too much or get stuck miles from anywhere. I didn't want to get spat off it on the road either if it locked up again as one near miss was enough... When we took it apart after getting home we couldn't believe what a mess it was inside. The mains were gone, so was the small end and big end and the piston was worn. Parts of the plating on the bore of the barrell had picked up and embedded themselves in the piston in several places and the rings were also welded into their grooves in a few places, the bottom one probably 90% stuck, both of these due to the heat seizure when the head gasket went. Despite all this the bike was still running fine, wasn't rattling, just a bit of a grumble from the mains and it was still pulling like a train with no apparent loss of power. It was still pulling 4th and 5th up the sides of the mountains on the moor crossings no problem and showing a decent turn of speed on the road. Looking forward to seeing what it goes like when the rebuild is complete

Yes indeedy, got the regs and definitely be riding, hopefully bring one or two more as well

who else is doing front pipes for TY250 twinshock apart from Miller?

Yes, as Pitley says, Godden framed 175/200. It has the bend at the bottom of the front down tubes. Mini Majesty tubes are straight. Only way to tell if it is a 200 is by the bore as they use a 70mm piston.

Piston is a DT360 piston which makes 320. The DT has windows cut in the back for the inlet. You can use a YZ360 but this has an arch cut into the skirt instead of window and makes the bike sharper and also wears out quicker. DT with windows is the better option. Or you can use a DT400 piston for 340cc but there is no point really, I can't tell any difference between 320 and 340 when mine was done. Back to 320 now anyway. Don't forget you need the spacer under the barrell with the 320 conversion to retain piston/port timing. Craig Mawlam has these although you could make one. About 2mm thick I think. Try a mate of mine, Colin, for the piston, this is a link to his website below. Not sure what he has left now. He can also get an alternative electronic ignition for the Yams which they have been trying on the Yellow Majesty you can see on the website under customising. ty offroad website The fibreglass tank from Craig uses the original cap from the TY tank. Not sure about the tap, I think they are made to take the Ossa/Bultaco type that are always on ebay - that's what mine has anyway. I think he may still have some used full size alloy tanks too. I've had no problems with my fibreglass tank, except it doesn't hold much, although I've not run out yet on a road trial. Front wheel spindle is fine, won't give any problems, same size as Ossa/Bultaco. Your exhaust shield isn't a Yam one, if you want an original try Ellastone, they should have one, or Alan Pedder at A & B Autos, Cheadle.

To answer the specific question 'is it permitted' is difficult as there probably isn't a specific rule that covers it. The only ACU ruling on twinshocks is that in the ACU Classic championship the bike must have been a twinshock at original manufacture and cannot be fitted with discs. In club events it is really down to the individual clubs what they will allow. Some allow Yam monos with twinshocks fitted to compete in and win the twinshock class, so fitting your 242 with the mono engine shouldn't upset them. In the ACU Classic the rules restricting modification are to stop that sort of thing (because where do you draw the line, a GasGas or 4RT with twinshocks should just as readily be accepted iof a Yam mono was allowed) and really to try and keep modification of the bikes ridden in the series to a minimum. A standard twinshock is more than capable of tackling the sections which are nowhere near as tough as the centre/national trials of the era, so there is really no need for serious mods. Bikes are more likely to be personalised than modernised. Given that some 240 Fantics are fitted with engines from the later 303/305/307 series then by definition, fitting the Yam mono engine in the 242 is no different. No-one bothers about the Fantics being updated with those motors so the same should apply to the Mont. But, it's also a problem of perception. The later Fantic engines look the same as the earlier ones, so it isn't an obvious update, unless you know what you're looking at, so the bike still looks standard. The Yam engine in the 242 will be an obvious mod. Does it matter? The Yam motor is superior in terms of performance so it could be argued that you're going to get an unfair advantage. My view is that yes, the engine is better but the events aren't about the need for power so it isn't going to help you float up the rocky streams of Bootle etc. It's also a mod you could have done when the bike was new as Yam monos were out 2 years before the others so they competed against (and slaughtered before finally killing off....) twinshocks. I'd say it's ok, don't know what other reactions would be - of course if you win on it, that will change peoples views, if you're at the back of the results, no-one would bother. People, as well as rules, are never consistent.... The only problem with mods like this is that it starts to push boundaries and you get the 'well if he's done that, I'm doing this situation'. And then where do you draw a line before it gets too far.

Having had a ride on a standard TY250 recently, for the first time, I was surprised at how nice it felt as all I've ever heard about them is negative. I know the front forks are under sprung and under damped from new and the rear shocks were useless on this particular bike, but the general feel of the chassis and the steering/handling was good. Engine was quite responsive too as the flywheel weight had been removed. I remember a Godden framed 250 Majesty that I owned briefly about 15 years ago and the engine was awful, flat as a pancake and no torque - which is why I always accepted the negative comments about the standard TY250. It must have been fitted with one of the heavier weights which killed it. Didn't keep it long enough to find out. I think if I was going to start with a standard TY and look to make improvements I'd forget raising the engine as they did on the Majesty. The standard bike has enough ground clearance and in my opinion doesn't need any more. It's debatable how much of an improvement it would make, especially as no-one riding one now is going to throw it up the same sections as they were ridden on in their time, sections in today's classic trials are nowhere near as tough as the National or Centre trials from that era. It's also an awful lot of work for how much gain?? I think I'd just do the shock repositioning, revalve the front forks (personal preference this as some people are happy with them, some aren't) reposition the footrests and 320 the motor as that sorts it out power-wise without any doubt. Contrary to what is sometimes said, the 320 doesn't need to be an arm-wrenching firework, they can be very soft and tractable but torquey enough to pull any gear. It's a pretty simple conversion too. Sammy Miller front pipe and WES exhaust (mate has one fitted to his 320 Majesty and it sounds superb - mine sounded like a bag of s**t with one fitted, don't know why but that's just the sort of luck I have... every other one I've heard sounds good) A mini or full size Majesty tank could be fitted to get the look - Craig Mawlam has either I think. I'd ride it like that and then think about maybe lengthening the swingarm a touch, depending on how it felt, it may not need it, but they are a short bike and a bit twitchy. On climbs, especially with the 320, they can be a bit front light, slightly longer swingarm helps with that and stability. They are very similar to an Ossa, as you'd expect as the Yam and MK1 Ossa share pretty much the same wheelbase, on the MK2 Ossa, which was after Mick had gone to Yamaha, the swingarm was lengthened by 1.25" If you can get a TY250 for for a resonable price I think a nice competitive bike can be made for a fraction of the cost of a Majesty or TLR etc.

About 2" taken out of the front down tubes and the rear tubes that go up from the footrests to the front/rear of the seat. This lifts the entire engine cradle upwards by that amount. The tube that runs under the frame's top tube needed a piece cut out of it just before the toolbox to clear the sparkplug/cap and the exhaust had to have a piece cut out to reduce its height to allow for the engine being raised. The airfilter to carb rubber was now a really tight fit and rubbed on the rear top engine mount as the engine was closer to the airbox.

When running an Amal MK1, the Ossa (250 or 310, they use the same carb) uses the same size carb, jets, slide etc as the older 250 Bultaco Sherpa. I know that Allens over Nottingham way have carb settings and jet sizes for the Mikuni for the Bultaco, so you could get those of them and use them as a starting point for the Ossa.

The airboxes come as a bare item, nothing else, the idea is that the original grommets etc are used from the old airbox. If you don't have the original box though, getting the filter cover plate may be a problem. They aren't available as a new item as far as I know. They are made from rubber and fit in the same way as a rubber grommet does - which is in effect what it is, a very large grommet. No nuts and bolts involved. Try Bultaco UK or John Collins for a secondhand one or maybe they can be sourced in Spain now, otherwise you'll have to make something. The sidepanel pins locate in rubber grommets which fit in holes in the airbox. You just drill them out to fit the grommets. These can be bought as new items and I'd recommend buying them before doing any drilling to be sure of the hole size. There are also 3 rubber 'funnel shaped' grommets which fit into the three holes in the top of the airbox, not sure what they are for other than to maybe direct air into the box from a direction that water can't be drawn in. Don't know if these are available or not but not sure they are really necessary anyway. Chances of finding a good second hand box are probably zero as they break up for whatever reason - hence the replacements

Thanks Frenchie, be good if you are able to get it done

A bit more on the flywheel weights. We were up at Mick Andrews' for a trial this weekend and my mate went to say hello afterwards. He asked about the flywheels on Majesties and Mick said that there were some fitted with different flywheels (not just weights, the actual flywheels) in addition to some having different sized weights fitted as well. Seems there are a few more variants from the standard TY setup knocking around out there.

Frenchie - be interested to know what modifications were made to the clutch, so if you are able to get them I'd appreciate it. Mine is useable now but far from ideal.

As you mentioned in your first post, there are quite a few alloy head/barrell variants, Parkins, Greeves, Dot, DMW and more that I can't recall right now. Problem with buying one off ebay is it is difficult to know what you are getting, it could be a kart, trials or scrambles barrell and unless you know how to measure the porting and know what the porting should be for each, or know someone that does, you won't know what you've got. I had what should have been a 250 37a Villers engine in a Sprite with a Parkins barrell and head. Turned out to be a 197 when I took it apart and it wasn't a 37a either I don't think. No-one could identify the barrell, best guess by Vale Onslow was that it was a Greeves and as it was 197, probably a kart barrell. Anyhow, converted it to 250 and when the engine was fired up it had no bottom end at all but revved like hell but it was all wrong for trials, messing with the compression ratio etc did nothing to make it useable. Gave up and sold it. The alloy barrells are a lottery in my opnion, so unless you are sure of what it is I wouldn't buy one - not to mention the stupid money they fetch too, as you've said. A lot of riders here in the local Pre65 scene reckon that the round iron barrell is a better choice for trials as the porting gives better trials power and some have gone back to those. There's no doubt that the alloy barrells look nicer, it's knowing which one to get that is the problem. Apparently though, new trials engines can be bought from Nametab in Redditch as I know someone who bought one recently and it had an alloy head/barrell fitted, so maybe someone is casting them again suitable for trials. If you're buying second hand though, beware - there are plenty of 'experts' out there who will tell you what it is but do they really know - in my experience above, no. Don't know what head/barrell is fitted to Mick's bike.

The mounting pins are placed differently on the 340 sidepanels as the mounting holes are in a diferent place on the 340 airbox. Pins are closer together

Easiest way is to bore out the existing yokes, that is how everyone I know has done it. I have mono yokes on mine but the steering angle has been altered and it has a replacement headstock to take the mono yokes/bearings. If I was to do it again I'd use the existing yokes. The statement about the trail being less on the twinshock yokes is based on what all of these others have told me, I've never checked it myself. If you want to use the mono yokes I guess you could press out the stems from each set and fit the twinshock stem into the mono yokes by modifying them to suit - maybe the trail could be altered at the same time, but boring out the existing yokes is the easier way to go

TY Mono forks won't fit into TY175/250 yokes, yo have to bore out the 250 yokes to take the mono forks. 175 forks are smaller again so I don't know whether there is enough metal in them to bore out for the mono forks, however, 175 and 250 yokes are interchangeable as far as I know, so fitting a pair of 250 yokes and boring them would be the answer if 175 too thin. You can't fit the mono yokes to the twinshock as the stem bearing sizes differ - unless you can overcome that of course. However, the mono yokes have more trail than the twinshock so you really need the twinshock yokes to keep trail to a minimum in view of the mono forks being leading axle. As for steering, as mentioned in previous post I tried a Yam framed Majesty with mono forks in it's own yokes and it steered fine, no problems at all.

Removing the weight will enable the motor to pick up revs quicker as there is less mass for the engine to move. The bike will therefore respond a bit quicker from low revs which may make it feel a bit torquier also. I rode a TY250 for the first time recently, same year as yours approx and this had the weight removed. I was surprised at how well the motor picked up as everything I've ever heard about these bikes is that they are a pile of crap. Not so at all, I was quite impressed with it to be honest, steered well, felt very much like an Ossa, as you'd expect... A couple of years ago I tried a 250 Majesty (most of these had standard 250 motors) and this had the weight still fitted. It was slow to pick up and felt lethargic, almost underpowered which it wasn't, I guess it was just the effect of the weight. With the weight off it would have been a very nice bike. The only negative aspect you may experience with it removed is that the bike may not 'plonk' as well at very low throttle when riding without the clutch. With the weight fitted, the extra inertia will keep the motor rolling over, without the weight you may find it stalls easier. Depends how you ride, if you use the clutch and brakes and ride with a tickover it won't really be a problem, if you ride on the throttle and no clutch with no tickover then that is when you may notice it stalls easier as there is less inertia to keep it turning with the throttle closed. At least removing the weight is not irreversible so the best thing to do is try it the next time you go out but take the weight with you so you can fit it back on if you don't like it. It's a quick job. Removing it may be another matter though if it has been on from new as it may be a bit stubborn...

My preferred set of rules too, as more in the spirit of what trials was all about. However, riders on modern trials bikes with modern techniques will never ride no-stop, they'll still hop and maneouver under the argument that they are still moving (missing the point that it's supposed be moving forward that is the object) It's what happened when the WTC went no-stop, they didn't ride no-stop by any stretch of the imagination. The SSDT is no-stop but stops and sideways hops still happen with the top riders when they get into trouble and 99% of the time it goes unpenalised - as it does in our own Classic championship. Don't know what the answer is to WTC and BTC lack of entries and personally, have no interest anyway, but I don't think the traditional style of no-stop is workable anymore in its true form due to modern techniques and modern bike capabilities.

Yes indeed - which is just what they've got - a few And British Championship has gone the same way, something around 10 at the last round, with 25 in the Experts and 6 youth riders

The Majesty doesn't have a different flywheel from the standard TY, they are the same item. The flywheel has a weight which is a steel ring bolted by 4 screws around the circumference of the flywheel. The weight can be seen in pictures and parts diagrams in the TY250B manual. Remove the weight and you have a lighter flywheel. Maybe some of the TY range came without the weight fitted.

First Majesties appeared 78? probably 79 with the modified Yam frame and the Godden frames appeared 80/81 so they both ran for roughly the same period of time so maybe the numbers are fairly equal. Don't believe everything that is said about the Godden framed bikes being superior to the Yam frames. Are they? The best Majesty I've ridden to date is a Yam framed 320 and it rode and handled beautifully. Only mod was TY Mono forks but the chassis was unaltered. Down to personal taste I guess.