feetupfun

If the M199B airbox/sidecover arrangement is the same as M198, I can help with photos of the original airbox. If you want photos, please let me know and I will do them this weekend. David

1. If you use TY mono yokes in a twinshock TY/Majesty frame, the standard mono yoke steering stops reduce the steering (side to side) angle severely compared with the twinshock yokes. Can the stops be trimmed back or are they just fundatmentally different in how they aremade? From memory new stops are needed on the bottom yoke to get enough steering angle ie they can't be trimmed enough. I would need to look at my riding buddie's bike (TY175 with TY mono front end) to be sure though. 3. TY175 yokes are made from the same basic forging as TY250 twinshock yokes so it makes no difference what you start with if you are going to bore them out to suit 35mm or 36mm tubes. If the yokes are bored out, should they be angled and offset a minute amount to account for the mono axle offset vs. twins shock centered axle? Would the reduced trail be a noticeable issue? I don't know the answer because I haven't done what you are suggesting. Remember that it is not just the axle that is offset differently on the mono front end. The mono yoke tube clamps are further rearwards than the twinshock yoke tube clamps relative to the stem and may well have a different angular offset too. One thing is for certain - if you bore the twinshock yokes out while retaining the same hole centres, you will only be reducing the trail by the offset of the axle so won't be too far wrong. Didn't someone else say it worked well to use the twinshock yokes bored out?

DabDab I agree that it would be great to be able to buy lightweight WES exhausts for our Sherpa Ts but WES already do make exhausts for the world's most popular vintage trials bike. It's just that the Sherpa T isn't that bike.

1. If you use TY mono yokes in a twinshock TY/Majesty frame, the standard mono yoke steering stops reduce the steering (side to side) angle severely compared with the twinshock yokes. 2. Yes the steering stems can be swapped to fit the mono yokes to a twinshock TY/Majesty frame. 3. TY175 yokes are made from the same basic forging as TY250 twinshock yokes so it makes no difference what you start with if you are going to bore them out to suit 35mm or 36mm tubes. 4. For people thinking about fitting Montesa, Bultaco or other Betor type forks to their TY/Majesty, carefully check the overall length to make sure the front of the bike ends up high enough because many of them are quite a bit shorter than the TY250 forks.

The local motorcycle shops here sell individual nipples and outer and inner of desired gauge by the metre. Cables made at home end up costing about $15 each this way. Alternatively their motorcycle mechanic will make custom cables for people at an hourly rate. Cables made this way cost about $40 each.

If you offset the forks or change their offset angle by altering the relationship of the triple clamp holes, you are changing the trail, not the rake. The rake angle is determined by the angle of the steering stem (steering axle), not the angle of the fork tubes. The factory MX teams alter the rake angle to tune the steering for a particular track by using eccentric bearing housings in the steering head. The easiest way to change the rake angle a lot (more than 1-2 degrees) is to do something like what Jay Lael has shown. Small adjustments can often be achieved by shockie length, fork tube height in triple clamps and spring preload front and rear but turning an oldish MX chassis into a Trials chassis normally requires some pretty serious frame work to get the steering nice.

Jays measurement will be correct only if there is no angular offset built into the triple clamps. Many bikes have this angular offset so beware.

Rake is the angle from vertical of the steering stem. It can be adjusted by changing the relative height of the front and rear of the bike (suspension settings or sliding the fork tubes in the clamps) or by using eccentric bearing seat inserts in the steering head or by cutting and welding the frame. Measuring the rake angle directly can be pretty tricky and is probably unnecessary. If you know how much you want to change the rake angle, the easiest way is to make an exact side view scale drawing of the bike then you can measure off the drawing how much you will need to change things (ie frame tube lengths) to achieve the change in rake angle you want. If you have access to modern drafting software it is possible to create drawings from photographs of structures.

Here in Australia all motorised vehicles (including trials bikes) are specifically excluded from my household contents and dwelling insurance policies. The only exception is for motorised wheelchairs.

$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