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You could start at a wheel builders for suggestions. Have you checked the acceptability of alloy hubs for a pre 65 machine. Some FB’s and James to name a few used smallish hubs not always alloy which might be less costly if you can track some down. You’ll also want the correct width etc for you forks and swing arm, mostly sorted with the correct selection of spacers. Oh and brakes that work not just look authentic. Try Gerry Minshall who you will find easily on Google.

You may also have an ignition coil that is breaking down under load eg cant produce sufficient energy at high revs to keep plug sparking.

Oh so its NOT having the latest most lightest, most ‘dialled in’ factory works bike and all and every day to practice then! Spain is one of the biggest transgressors of EU rules so FIM rules or any other organisations rules are so much old news. We on the other hand daren’t even take a headache pill before riding....in any event etc.?

If you use Automatic Transmission fluid in place of a heavier weight grade of oil then although no apparent damage is done, the down side can be for some bikes that the transmission is noisier or rattles at low idle or both. There are different types of ATF so pick carefully. ATF works extremely well in nearly all all metal clutches in bikes as the oil can work at really high temperatures just as it has to in a vehicles auto trans.?

Carb off and clean, tube attached to fuel inlet, gently blow using mouth into tube. Hold carb upside down, repeat blowing action....you should feel resistance to your air pressure. Float bowl off, repeat using a finger to gently lift float up....I’m guessing the float is attached to the carb and not sited in the bowl.... and lower the float allowing air in and stopping as you move the float. If the float is bowl sited then make sure any guide posts allow the float to move up and down smoothly. You will need to find actual height setting specs from the manufacturers manual. If the crankshaft oil seals are worn then this will allow a loss of crankcase compression and mixture which will affect engine performance and this is where I would be looking. If you can pull the crankshaft in and out by much then you may have worn main bearings which will load the oil seals more causing fairly rapid lip scoring. This will allow both air in and out while the engine is running. As a final few points to check as you seem to have covered most everything else, poor compression, badly worn cylinder bore, partial seizing...oil mix ratio+cooling issues. All can create similar symptoms to yours as described?

I wouldn’t be too critical of your current riding style, especially over ‘that’ obstacle....you clear it with minimum fuss. Most of the noise is suspension and chain whipping. Looks pretty much how most would ride over that type of hard edge. Maybe practice on a flat surface just kicking the rear up slightly with body weight transfer, a bit like a see-saw action from you using the bars to push your weight against and legs to try and bounce upwards ( a*** in the air style) once the rear starts to come up inertia and the suspension unloading momentarily will do the rest. Personally if you are clearing the obstacle you will only see it or its type for every lap, not dozens of times. You’ve obviously thought about this particular issue a lot, so you have planned to clean it, then ridden to clean it, mission accomplished. Now move onto increase your other skills. Also bear in mind your bike is a little heavier than the 2T bikes so reaction from the bike will be a tad slower, but that comes into the planning part???

Should have maybe used the back of the score sheet.....but then you would have scored your a***?Bet you’ve added toilet paper to your riding kit!

They should in theory slip straight in. Can’t see why Willybul has not carried out feetupfun’s suggestion!

57 whippersnapper?You’ll like the Beamish more when you get to know it better. Practice makes perfect.

Theres no comparison to actually trying on before you buy.

What year Sherpa T as the early stanchions were tapered at the top.

Yes they are heavily modded, those extension plates are 7 mm thick....TIG or stick weld needed if you use similar. They do bend as well so I use a tool to lever them back into position....its a weight thing?. You will notice that the original footrest stubs are retained so grinding off the welds means I can return the bike to standard quite easily. Because of the rear brake pedal location you can get away with the original brake cable, the adjuster just has to be wound in further. The brake pedal stop bolt is too long ( just in case any eagle eyed viewer comments) its a new bolt and it will be shortened...another weight thing. Also the airbox is missing....I’m making a replacement....read made a replacement.?

There you are modded rests etc? Please ignore rusty chain this is before refurb.

There is a great big void when it comes to rider ability and ‘any’ machine they care to ride. I agree with you entirely, ‘a good rider on a ( should we be saying standard here?) TY 175 or TY 250 could compete in classic trials at a very good level’....and I’m sure they do. Certainly Mr. Shirt and Co hovered up the remaining stock, if I remember correctly the 250 came one per crate but the 175 and 125’ came in two per crate. But they did not hoover up that many! Yamaha were more concerned with the many hundreds that were languishing unsold and un ordered by the dealer network in the US, plus other parts of the world. Another issue that was troubling potential buyers was that some felt the power delivery for the 250 was too abrupt, a rumour or otherwise distraction put about by some to steer customers in another direction! The other concern was the TY was more heavy than some of the other options. My own thoughts on the TY were considered on my experience of dismantling brand new TY’s, then building them back up again using Majesty frame kits. The ground clearance was a bit low, The lighting system, wiring harness and switch gear were too road orientated i.e. some of it straight off the DT range. The handlebars were flimsy and weak at each bend...most people would throw the OE one away and fit aluminium. The exhaust was a bit heavy and restrictive, entirely understandable considering street use noise rules etc. So lots of extras needed if you were going to be seriously trialing, where as the Fantic was a different ball game, lighter and better steering, less threatening engine, all the right bits on the bike from the start. There were quite a few Fantics being campaigned by riders that either got a brilliant discount or free even to use, that was a marketing strategy that put Fantic in the buying publics eye, not sitting around in a case in a warehouse waiting to be bought. Whatever stpauls buys I’m sure they will enjoy their ride. Cumulatively we have provided more than enough information and history enabling a decent machine to be purchased. ?

Best check carb jet sizes again, those pictures look as though the plug has been extremely hot, hotter than the grade of plug used. The gap will have an influence on spark power. If you carry a plug put it in a container that will protect it from the other stuff you carry. Your petro-chemistry is questionable in that the additives might not be suitable mixed together. If that fuel worked in your M/X bike ok then it might be the fuel has gone stale past or it could be the amount of oil you are adding is lowering the octane rating too much.

Theres a place in Chesterfield might be able to help with a kit or suggest a replacement. Think its Powerhouse might be wrong on the name but Google should help.

Could be interested but a price expectancy would be helpful....to many Dutch Auctions around at the moment! Nice to have someone looking for you. I’ll be in Spain Octoberish...not looking for bikes, but I could be.

Yes I do realise the pounding the sides of most fuel tanks get especially trials bikes. Pushed and twisted by the riders legs from balancing, turning and the bike dropping to the ground. Lets not forget the errant tie down or rope being tightened down on the tank too! Mud and grit and the seams on riding gear are not a good combination for fuel tanks either. My 250 Sprite tank had a split in the side before I even got it to a trial or practice area. I was just 16 though and impetuous ??

I used to sell brand new Yamahas, road, trial and enduro. John Shirt was not too far away from my shop so naturally I sold some of his kits and other items too. The difference between a factory standard TY and a Majesty were chalk and cheese. The TY’s were better made than some of the Spanish offerings and my personal favourite is/was the TY 250 E. I thought the mark one version was too bulky looking more like a scrambler with a low front mudguard, my opinion. I got to ride John’s development Majesty 320 which had a YZ80 front hub and other bits for testing. This was at a test day that I organised at a local quarry, many people were offered the chance to try standard TY125, 175 and 250 machines. A few were offered a try on a Majesty 175, 250 and some tried Johns bike including me as I already said. The standard TY was slow to turn whereas the Majesty was much quicker and more predictable....yes Mr. Andrews certainly knows his stuff and he and John produced excellent results. Yamaha were struggling to sell the TY range and did pretty much anything to shift stock. The Importers at the time, Mitsui, Oakcroft Road, Chessington. would lend you a demo bike without much difficulty at all. I borrowed a TY 125 for a charity weekend event, we rigged the throttle so it couldn’t be revved high. Set up an easy obstacle route ( the event was in a riverside park) and used straw bales to prevent running into any people. We charged a nominal 50p for two laps. The guys working on a nearby fun fair, also part if the event queued up and paid their 50p except some thought they could overcome the restricted throttle...it held! So what with those guys and the public that waited patiently for their go the 125 was running virtually continually for Saturday and most of Sunday. The TY 125 was great bike running faultlessly, using a tiny amount of oil ( we kept it standard so it retained the oil injection) and my partsman only went for fuel a few times. So I feel justified when I say the TY steers slow when compared to some of the other machines on sale at the time. Just fitting longer rear damper units at the rear would quicken the steering a modicum. There is somewhere on the web a whole story on modding the TY frame and steering head angle to quicken the steering. Lets not forget that the TY range was aimed at the larger USA market, so it was in Yamahas best interest to produce a bike that had reasonably stable steering and not too twitchy as they realised that many TY’s would be used on the trails rather than trials.?

The TY engine is more difficult than say a Bultaco if you are new to engine work. Otherwise with care they can be sometimes less problematical. I don't think I mentioned crank cases, sorry if I confused anyone I was referring to the outer cases. I still have the AJS factory supplied gudgeon pin circlip pliers that came with bikes tool kit, they’re dinky but so useful. They are a permanent guest in my top tool box drawer?

Yep, agree entirely with the correct positioning of the kickstart lever. Usually at the same angle as the bolt on frame tube or slightly closer to 12 o'clock doesnt look as neat though. Except when you have a really tall and strong bloke kicking like mad with the bike leaned well over, this enables the kickstart to be forced further round and knocking ‘seven bells’ out of the crankcase!

Excuse the pun sparkieb, but thats quite a crack you have there! Studying your photo there appears to be other cracks in the casing. I don’t know what Montesa were thinking about when it came to the kickstart stop, relying on the rider to kick only as far as the footrest seems farcical to me. My 348 has a chunk missing but without the other cracks. If you get the case welded its only going to get mullered again the next time you use the kicker in anger....say in a section or someone else does the kicking. I have opted to use a Polyester sealant that a) will keep water out if wading b) will flex and potentially stay in place or if it falls into the magneto then it shouldn’t do harm if any. My 348 has modded footrests S3 pegs, lowered and back mounting plates so the footrest no longer acts as a kicker stop. I’m considering a simple drop down bar fitted in the original footrest mount hole...we’ll see?

You are probably correct but that was 40 years ago and environmental issues have seen the petroleum producers changing the formulas to the detriment of many things including fibre glass. As a previous owner of a few fibre glass boats you rapidly learn a lot about the construction and materials used. Therefore you find out that fibre glass and its gel coat are not waterproof and will absorb water over time, hence the dreaded lift out and drying out time usually every year or two depending on how affluent you are? Petrol or any liquid will be absorbed in a bikes GRP tank if left in for long periods. My Montesa tank had what us boaters call Osmosis that is bubbling of the sides of the tank, a paint specialist friend reckoned it could be micro blistering of the paint finish, the tank had been repainted at some stage in its life. A quick test with a pin proved that it was ethanol attack, the strange thing is that the base of the tank was clear of any bubbling; but then there was no gel coat applied in this area? So some bright spark petro-chemist decided that ethanol would be good to reduce petrols environmental impact....without considering some of the potential issues.

Hi faussy, All I can say is the price is extremely good. Yes the maker is producing a mould from my original tank, pretty much how most people go. The exception here is that I asked for reinforcement in the seat and side panel areas.

I have been restoring a Montesa Cota 348 Malcolm Rathmell Replica over the last few months, unfortunately although the tank/seat unit looked very good the dreaded Ethanol has attacked the inside even though it had been treated with a sealer ( make unknown). Great lumps of the stuff could be heard rattling around inside when the tank was shaken, after fishing as much out as possible ( depressing work) I realised that the only really effective repair would be either an alloy tank beneath a shelter or a complete alloy tank and seat unit both of which were turning out to be expensive options. I set the unit to one side and pondered my next course of action. Fate played an Ace for me when I took some friends to visit Adrian Walkers Spinning Wheel Classic Cars in Dronfield near to Sheffield and Chesterfield. Apart from seeing plenty of bikes both road and competition based I saw sitting on top of an arcade machine a beautiful red glass fibre fuel tank. Can I touch this I asked Adrian, no problem he replied I’ve just had that made. It was to say the least an outstanding piece of workmanship. The underside was as good as the topside, there was no sign that it was fibre glass no mat no smearing just perfect. I removed the filler cap and peered inside, incredible there was no mat or strands evident. Who made this I asked and was shown an invoice for the tank. I made a note of the maker and the following day I made contact enquiring if he could make me a new seat and tank unit. Well I haven’t got a mould for that but I could make one. Will the Rathmell signature show on the new product, yes was the reply. Please go ahead. If you are looking at having a new Ethanol resistant fibre glass tank made for your bike then Roger Ennis is the go to man. This is not a sales patter and I hope that the moderator approves. Rogers been making fibre glass tanks etc for years and knows his stuff, a very entertaining and interesting person to talk to. I have asked his permission to pass on his telephone number which is 01594 562361. ??