feetupfun

$AU52 is a pretty normal price for a TY fuel tap. Those diamond shaped seals can be bought separately if that is all that is wrong with the tap. A better tap for TY250 and TY175 is the Kawasaki KT250 tap. About the same price but uses a different idea for sealing which lasts longer. No idea if a DT250 tap is the same as TY250A.

Mines a recently assembled Majesty using a NOS Godden frame kit and the running gear from a TY250D. Aluminium replica Majesty tank from France Trial Classic. 340mm Falcons with 60lb springs. Standard exhaust with new front pipe. The motor is currently a standard (250) except for the lightened flywheel. Photo from a recent club trial courtesy of Drew Wickerson

Dear zotz The 1974 TY250(A) has a seat with unusual construction. There is a moulded foam piece which usually goes so hard it feels like wood as you describe. There is a pressed steel base in there which by now is usually mostly iron oxide. The cover is stuck to the foam piece and hence inseperable. The seat is screwed to that wonderful fibreglass seat surround that gives the bike a very distinctive look. With a bit of persistence you should be able to buy a fibreglass replica seat base to suit the A model and take it from there yourself or take it to an automotive upholsterer with a good picture of what it looked like in 1974 to go by. Yamaha made some replacement seats for the TY250A and TY250B with plastic bases. I know only because there was one on a bike I bought with the part number sticker attached. I don't think they are available any more from Yamaha. There are complete new seats available for the C and D model TY250 but you will need a new, longer (C, D model) rear mudguard and some small mounting brackets added to your A model frame to make it fit. David

Yes that gearing is a bit high. I use 12/53 (428 chain) which is the same gearing as 10/44 and my first works well in tight stuff. Yes you will need second gear for climbing big banks.

1. If it idles, there is nothing wrong inside the motor so don't pull it apart again. 2. You haven't mentioned checking the fuel level in the float bowl. 3. You haven't mentioned checking that the reeds close properly. 4. Are you sure a rag or a wasp nest didn't get into the exhaust pipe while it was off? 5. Have you checked that the jet size stampings match the actual hole sizes?

Neo I'm not sure if this is any help, but the head of that REV3 bottom shock bolt is a precision fit into its hole so you have to get some penetrating lube to the side of the head as well as to the thread. The REV3 I worked on was three years old and that bolt had never been removed before. After a few days soaking it with Silkopen it came free without resorting to heating it. David

Yes I used air caps on my TY175 for a few years in the 1970s both with and without steel springs. You already are using air pressure as a spring in standard TY175 forks but with zero preload (atmospheric pressure). You can vary the overall spring rate to prevent bottoming by increasing your oil quantity if that is what you want. Careful measurement of oil height is required though to ensure the forks are getting full travel. Yes air caps "work" because: You can fiddle to your hearts content with spring rate and preload by varying oil quantity and gas pressure. However air caps are not used much in real life because: The gas heats up and cools down depending on ambient temperature and bike use and so changes your carefully adjusted pressures. The gas volume in TY175 forks is so small it is very hard to get the pressure where you want it. The increased pressure causes increased drag on the fork seals. This is not good for suspension action on a trials bike. For the same reason the fork seals wear out faster.

Ever since my TY 175 became 205cc, I have been breaking kickstart levers frequently. Yes they are easily available but it becomes expensive having to keep buying new ones. I have experimented with different home made designs but am not happy with any of them yet. The Mini Majesty featured on page 38 of Classic Dirt Bike Issue 2 (Ted Salmon's bike) has a kickstart lever that resembles the Yamaha item but looks a bit more substantial at the knuckle end than the Yamaha item. Maybe it's just an optical illusion in this case but does anyone know of where TY175 kickstart levers of a superior design are available from? Thanks

Steve Mine says 81 08 106 so I'm assuming made in August 1981 David

Sounds like you are pretty keen to pull that Z motor apart. From memory, the puller for the magneto flywheel is the same as for the TY175/TY250.

Unless you are made of money, don't pull anything apart till you know what is wrong with your Z. You need a much better diagnosis. I'll try and help. First off you need to describe the symptoms much more clearly. Why do you think it is "oiling up the cylinder" and what do you mean by killing spark plugs? There are many reasons for losing spark and changing the crank seals is probably the last on the suspect list and the most expensive to do. If your crank seal on the clutch side has failed, gearbox oil will be getting sucked into the engine so you can easily diagnose this by the gearbox oil level going down with use and the exhaust gas being very smoky and smelling unusual. Your spark problems may be something much easier to fix so how about some better information about what is happening with the bike.

The frame kits that Craig is now selling are made on the jig used for the last of the 250/320 Majesty frames. These frames differ in many ways from the TY250 frame. The wheelbase is longer, the motor is higher, the swingarm is longer, the footpegs are much lower relative to the motor and the shockies are mounted to provide about 6.5 inches of rear travel. The overall effect is a bike that has much better ground clearance, much better rear suspension action, better balance, better stability, more room between the pegs and handlebars and very similar steering. The only thing that is not quite as good as the TY250 framed bike is the front wheel takes a slightly wider line in tight turns due to the longer wheelbase. The other frame you are talking about I'm not sure if you are looking at a mini-Majesty framed bike or a Majesty framed bike. The Majesty 200 frame is the same as the 250/320 except for the differences needed to mount the 175 motor. The Mini-Majesty is a completely different frame that is much smaller and uses the Ty175 swingarm. The mini-Majesty suits riders of small stature and is very light. Newly made full-sized Majesty frame kits to suit TY175 running gear are available through France Trial Classic. NOS Mini Majesty frames are available through Craig Mawlem.

Thanks Woody. I'm happy that you have debunked my conspiracy theory. I'm now trying to work out if all that work on the frame would be worth it.

If the float arms are close to horizontal when you hold the carby upside down you are pretty close. You may also want to check if either of the floats has a hole (and full of fuel). The most common cause of what you describe is a worn float needle/seat. If the fuel height is too high of course it will run rich. I would be amazed if fuel came out the float bowl vent while the carby is up the right way. More likely to be the float bowl overflow line (the one that comes out the bottom of the bowl). I've just looked at the owners manual and the text says the fuel level should be 4~6mm below the joint between the main body of the carby and the float bowl. The diagram shows the measurement as 2~4mm below the joint. To check the fuel height the way the book says requires a special fitting that replaces the float bowl drain plug with a clear hose on it. If you want to see the page from the manual, send me an email and I will send a scan of the page.

If the float arms are close to horizontal when you hold the carby upside down you are pretty close. You may also want to check if either of the floats has a hole (and full of fuel). The most common cause of what you describe is a worn float needle/seat. If the fuel height is too high of course it will run rich. I would be amazed if fuel came out the float bowl vent while the carby is up the right way. More likely to be the float bowl overflow line (the one that comes out the bottom of the bowl).

I'd like to explain my conspiracy theory about the early Majesty frames based on the TY250 frame. I have studied photos of Majestys of the type that use the modified Yamaha TY250 frame till I'm blue in the face and am not convinced that the motor mounts were moved in the frame. Yes I know that is what is said in the famous magazine test "In The Rough" when these early Majestys were publicised but I reckon it is bunkum. Yes the motor is higher from the ground than in a TY250 fame but it is done with two simple modifications: One is that the swingarm is set at a steeper angle down at full droop. This lifts the rear. The other is that the main frame loop has had about 25mm added to the length of the top tube. This is where the modifications to the toolbox section come in. They are just a result of the work to add the extra bit of frame tube. This lifts the front of the bike (and steepens the steering angle) because it causes the front section of the frame to pivot forward around the front motor mount bolt. Maybe the top tube is lowered too. I don't know because I've not seen a detail photo of one with the fuel tank off. The reason I started thinking about this was that I had a few spare TY250 frames and wanted to build a Majesty replica but if you have a close look at the TY250 frame, the technical difficulty of raising the motor even one inch is quite extreme while achieving the same result using the method I have described is quite simple. If someone can debunk my conspiracy theory I would be very pleased. Good close up photos of the top frame tube modifications and of the rear engine mounts would be quite sufficient. David

Similarly soul searching is the issue about whether to allow the Yamaha MX400B in Post-Classic motocross events. Here in OZ, Post Classic MX is for pre-75 bikes and the MX400B came out in late 1974 so should be eligible, but like the OW10, is also a (cantilever) monoshock bike. I reckon that if we were lucky enough for someone to turn up on the OW10 at a Twinshock trials event, we should welcome them with open arms to have such an interesting bike to watch. The more competition oriented riders can be assured that such a bike would not provide any technical advantage over late model Twinshock trials bikes. There are good reasons why trials bike design did not follow along the lines of the OW10.

Perhaps the numbers would be different if the riders had their choice of riding two or four stroke. Being factory riders means that they usually don't get to choose.

The concept of protecting the tank by putting it within the confines of a perimeter frame might be an advantage depending on whether you put a higher value on the frame or the fuel tank. I personally think it is easier to fix or replace the tank than to fix or replace the frame in the event of that part of the bike being hit hard enough to damage it.

Its probably dry bearings or brushes and may be able to be fixed with correct lubrication which may entail pulling the fan apart. Is it possible that water has entered the fan motor from a high pressure water blaster? It seems that every trials bike I know that has had the cooling fan motor fail has an owner who cleans the bike with a high pressure cleaner.

My Majesty 250 is finally ready to ride. Was put together over the past few months from a NOS 1981 frame kit. As fas as I can tell there are now three 250/320 Majestys in Australia. Photos on the Trials Australia website. http://www.trials.com.au/BB2/viewtopic.php?t=2420 David

I had the older treatment for short sightedness (radial keratotomy - radial cuts partial thickness of the cornea) in 1995 at age 36 after wearing minus 3 glasses for 23 years. I had tried all the types of soft contacts available at the time but my eyes were too dry for them to work for more than a few minutes. The radial keratotomy RK technique is now about 45 years old and was developed in the USSR. As with LASIK the results were astoundingly good for activities like Trials riding, swimming and snow skiing (yes we have snow in Australia). It is now 12 years later and my vision for driving and riding is still fantastic but I am 48 and old-age vision has crept up to the point where I need reading glasses for close work. LASIK was available at the time but was relatively new then so I chose the time proven RK method. Time has since proven the LASIK method as also being successful long term. I would have paid lots more than what it cost to get the results I got but don't tell the eye surgeons that.

Of the covers made by Yamaha, the 1975 B model and later models had a flat cover with a bump in the middle and covered the sprocket and are made from magnesium and painted silver The 1973/74 A model has a domed cover that is aluminium with a polished finish and also covers the sprocket. There are also covers made by specialist UK trials suppliers which are flat with a bump in the middle, don't cover the sprocket and are of much stronger (thicker) construction than the magnesium and aluminium Yamaha covers. If you want photos of the three types, send me a PM.

If you explain what pilling is and in what way the clutch isn't working I will have a go at helping you. It would also be good to know: How long have you had it? Did you work on the hydraulics or just on the clutch assembly? Did it work OK for the previous owner?

The usual reasons for a failed big end in a two-stroke: Corrosion due to being stored with only fully synthetic premix oil for protection. Corrosion due to motor being filled with water by accident and not immediately dried out. Pre-ignition and/or detonation over an extended period. Poor air filter maintenance practices (usually affects the bore and piston/rings first). Its pretty hard to read your message without any punctuation but it sounds like either your mate only just bought the bike last weekend or you only rode it for the first time last weekend. Any other clues about the bike ie how did it run prior to the failure and what sort of riding does the bike see?