feetupfun

Hi Michael Yes I have ridden both a M92 and a Cota 348 in standard trim recently. I would have said that the 348 responded to throttle input faster than the Sherpa, and the Sherpa had a slightly higher resistance to stalling at extremely low RPM. Are you sure the 348 you rode still had the clutch side flywheel in place? They are easy to remove and some people prefer the bike without it. David

Dave what did you think of the handling and steering of the Miller framed bike compared with your M92?

PeterB Where do you recommend getting one of those DellOrtos from? Thanks David (also from the West Island of NZ)

This may help you with your TY250 cylinder ID. The first TY250 twinshocks (sold here in 1973 and 1974) were called TY250 and had engine and frame numbers that start with 434. These tend to be called TY250A nowadays. The stand is on the frame, the tank is steel, there is a TK carby, the bashplate was fibreglass and they had the bulging engine covers. I suspect the next model was not sold everywhere in the world but here in OZ there is a model that was released in 1975 we call the TY250B that also has an engine number prefix of 434, but the frame number prefix is 493. The B model has an aluminium fuel tank, the stand is on the swingarm and they had a black Mikuni carby. The relevant bit here for you is that while the A and B models both had an engine prefix of 434, the B model cylinder finning goes all the way around the front above the exhaust, while the A model cylinder has a wide gap in the finning there. Later model cylinders (1976, 1977) have full width finning all the way down the cylinder. I've heard annual sales of TY250, 175 and 80 were around 30,000 throughout the mid 1970s.

Hello Felix If you are getting gearbox oil into the crankcase once the motor gets hot, you may have a problem with the vent for either the gearbox or primary drive case. If one of the vents is blocked, there will be pressurisation when the oil gets hot. Bultacos like yours usually have two vents - one for each compartment. The primary drive vent is usually a hole in the filler cap (at the front end of the primary drive casing) and the gearbox vent is usually a hole through the filler plug (located under the carby). The path of the oil leak may well be as Swooshdave found with his bike (through the centre gasket), or it may be through the crank seal or crank seal holder gasket. You may find the leak is not a problem once the pressurisation problem is fixed. David

You should make the electrical connection between the red coil and the frame as good as possible. If that means cleaning the paint off the mounting screws and washers then yes do it. If you have painted the mounting tab for the coil, or if it has a film of rust, it would be a good idea to clean up the mounting tab where the red coil makes contact with it to maximise the quality of the connection.

I fitted Boyesen reeds to a TY250D twinshock motor at the same time as it getting a rebore. It needed the air screw adjustment changed to get the jetting right again. I cannot feel any difference in performance or response riding that bike compared with another bike I have with a recently rebored TY250B motor fitted with standard Yamaha reeds. Both motors are standard except for both having their flywheels lightened the same amount. A riding friend fitted Boyesen reeds and a reed case spacer to his TY175C at the same time as a rebore. He could not attribute any performance improvement to the reeds or the spacer.

I can remember my Dad suspending a whole Norton 16H by the barrel when I was a kid. The idea was that the weight of the bike would keep the piston/cylinder sticking issue under load continuously. Soaking in penetrene and a hit on the piston crown every day with a wooden drift got it moving after about 4 weeks - lots of patience there. The 16H had been parked beside a sand track through the dunes at the back of a beach for about 20 years (with the oil tank lid open)

My (1976 Oceania) TY250 has an ignition diode, but it is a solid black object about 5mm square and 20mm long, in the ignition wire between the points and the HT coil and is located near the carby. The object on that European TY250 in the photo looks to me like a power resistor used to reduce the current to the battery when the lights are not being used, or in the case of the bike not having a battery, to reduce the voltage to the lights.

If you want to work out if your tyre is a tubeless type or a tube type, read the writing on the tyre wall. It should say "tube type" or "tubeless"

The timing does not have to be wrong for the motor to run backwards. With the timing set perfectly for running in the normal direction, a TY175 will also run backwards. It will be less responsive and less powerful than when running forwards because the timing will be retarded compared with ideal. Although it is possible to get one with good timing running backwards by half-hearted kicking, if it happens frequently, the timing is probably too far advanced.

Hi Copemech Yes we can buy Notoil here in OZ. The local Yamaha dealer gave me a sample pack to try for feedback a few years ago. I found it works well when freshly applied, but dries out much faster than the normal air filter oils. Yes it's more convienient and probably more environmentally friendly, but if a bike only get ridden once in a while, then you need to do the air filter service close to when you want to ride, rather than servicing it at the most convienient time. David

No. WD40 is not sticky enough to trap the dust particles, and will dry out quickly. There are oils made especially for the foam type air filters commonly used in off-road vehicles and you should be able to import some of this oil from wherever you bought your Gas Gas or a local motorcycle shop in China. It is just called "filter oil for foam air filters" and there are many brands. If you can't wait to ride your bike till you get proper air filter oil, use the same oil that you are going to use to mix with the petrol to make your fuel. It will slowly move out of the foam by gravity but if you reoil the filter frequently it works OK. For whatever oil you use, make sure all the foam is coated with oil and that you have squeezed all the free oil from the filter before you install it. Foam not fully coated = dust gets in engine = motor wrecked Too much oil = carburettor affected by oil flowing down from filter

Dave I think I have worked out what is going on with Woody complaining about Michelin tube type rears - there were/are two types of Michelin tube-type rear trials tyres. The one I used successfully for years and would still buy if I could get them is the X11 tube type. They are/were terrific to use but became more and more difficult to buy here, being imported only twice per year, and the flat track racers snapping up most of them. About two years ago I heard that Michelin were developing a tyre that will fit both tubeless and tube type rims, but in searching for them, I discovered that Michelin also make a tyre that looks just like a proper trials tyre, but is not a radial and is not called X11 tube type. I don't remember what it is called exactly, but I have seen one on a M198 and saw enough to know that it is pretty useless for trials competition. David

Assuming you mean Godden Majesty frame for TY175 motor Early 1980s Appears to be the same angle as standard Yamaha TY250 and Godden 250/320 frame. Only know for sure that the wheelbase is longer than the TY175. Suspect it is the same as Godden 250/320 which is 25mm longer than TY250.

Cota 200s are nice to ride and relatively light. Montesas of the twinshock era are generally well designed competition machines that won many titles at a high level in their time. The Cota 200 kickstart mechanism has a weakness and the supply of genuine parts to fix it when it breaks have been used up. I haven't heard of anyone making replacement parts yet. The weakness with the kickstart is a design issue that is shared with a few models that use the same mechanism (mainly Cota models 172, 200 and 242). There are design weaknesses with all bikes, including Jap bikes. Other Montesa Cota models have different weaknesses. Maybe you could do a bit of searching on the forums on this website to learn more about twinshock Montesas.

The Mini Majesty frame for the TY175 motor has a wheelbase shorter than a TY175 frame and a steeper head angle. The series 1 Majesty 175 is based on the standard TY175 frame and shares the same wheelbase and steering head angle as the TY175 frame. The Godden Majesty made for the TY175 motor has a longer wheelbase than the TY175 frame and a steeper head angle.

There must be thousands of them at wreckers yards from other TY250s. I can send you some from orstraylia if you are stuck finding some.

Yes your TLR200 came with 2 rim lock holes on the rear wheel. Yes you can ride the TLR with your new EXCEL tube-type rim and no rimlocks but you will need to run approx 15psi to stop it slipping which will make it useless for trials. When you finally drill the holes for the rimlocks, choose locations situated in the gaps between two groups of four spokes. If you study the rim you will see that the spokes are arranged in 9 groups of four spokes. In the gap between the groups of four spokes the spokes are angled away convieniently away from each other. You will find 8 such locations on your rim. Someone previously suggested fitting the rimlocks at 90 degrees from the tube stem. This will work nicely for tyre changes but be aware that the standard rimlock locations are opposite where the tube stem hole is and in the the next gap to the valve stem hole. This provides the least disturbance to wheel balance by the rimlocks. If all this is a bit confusing, just have a good look at another tube type rim that has rimlocks fitted and you will work it out. You might get away with one rimlock if everything else is right and you use a high quality rimlock, but most people just use two rimlocks and avoid problems. An easy option is to spend some more money and fit a tubeless rim and no you cannot make you your EXCEL tube type work reliably without a tube (the bead seat is the wrong shape and the wrong diameter and the spoke holes will leak)

That seat tank unit is a Sammy Miller product and no they were not fitted to TYs from new. The exhaust heat shield is home-made. The main exhaust chamber that is on your bike is an aftermarket type and does not come with a heat shield but probably should. A neater looking heat shield (made of metal or composite fibre) would improve the overall look of the bike.

Further possibilities are: The drive key for the crankshaft sprocket has sheared. The person asking has never before started a bike with non-primary kickstart and is pulling in the clutch lever when kicking.

I hope this tastes better than it smells

Increase the preload till you get half travel with you on the bike in riding position. Yes just wind in the spring seats. You won't be able to tell if the springs are the right rate for you until you set the preload. You will have the right rate springs when you have 50% sag with you on board and about 5mm sag without you. If you set the sag to 50% with you on the bike and there is no sag with you off the bike, you need higher rate springs. I would have thought for an 80kg rider on a TLR200 that either 50 or 60lb/inch springs would be pretty close. Falcon springs are usually engraved on the flat part at the end with the rate. Once you get the springs right, then start thinking about the damping. Yes I did experience this with my first set of Falcons (springs being too soft) and since then I have specified which spring rate I want when I buy them.

The whining of a Beta is usually the primary drive gears - the gears that transmit the power from the crankshaft to the clutch basket. Betas and a few other bikes make that noise because the primary drive gear teeth are straight cut and this is a good thing as it prevents side loading of the crankshaft and clutch bearings and reduces the overall power lost through the gearbox. Many people like the noise and even seek it out.

I'm guessing the bike is a Cota 349 and it sounds like the clutch is slipping. Try easing it just past top dead centre before taking the kickstart back to the top again then do the starting kick. Also suggest you post in Twinshock forum for further queries about this bike as most postings here are for modern Montesa/Honda bikes. David