feetupfun

yes if you choose the right person it is possible to weld-repair magnesium castings. Yes it is a specialised job. My brother-in-law does this work regularly (he's in Australia though)

Hard to work out from what you have written, because there are only two MAR colour schemes and neither have any yellow or any black stripes.

The points should be touching with the flywheeloff so at least one problem is that the points are stuck open. I would replace any old-looking wiring because with vibration, the copper conductors work-harden and eventually break. What is that black thing with the green and yellow wires,a horn? ingition keyswitch? speedo?. The points cam follower and oil wiper look very dry. Have a look inside the flywheel at the points cam too and see if it looks OK. It needs to be smooth, clean and very lightly lubricated, or the points cam follower will get worn away very fast.

yes, undo the clamp bolts to reduce the chance of the thread jamming. It does make quite a difference

If you have contaminated the friction plates with friction modifier additive, it will not clean up by just changing the oil back to non-friction-modified. Having said that, I thought that including friction modifiers in car engine oils went out of favour years ago

Thanks oxboy. Sorry about the aluminium fuel tank thing. I don't know what made be think that. Your old bike leaning against the wall looks exactly like mine except for the tank. Your google search suggestion has also helped me to see how to modify a TY175 brake pedal to fit that frame. Also in the search results there were photos of a (full size) Whitehawk that shows that they have square top frame tubes, which someone was disputing. It also shows great detail about the frame design and in every shot the frame construction details are the same as on my frame.

I've done some assembly and posted comparison photos and dimensions of the bike here. It's a long forum string. The post date is 9 June 2012 http://www.trials.com.au/forum/viewtopic.php?f=16&t=4785&start=420

For external appearance, the closest crankcases are the DT175 A,B,C,D but the internals are different and so internal parts may or may not not be interchangable between motors eg crankshaft, gearbox, clutch. From E model on, the TY cylinder and flywheel cover wont fit. Yes the kickstart return stop can slip on the kickstart shaft, allowing the shaft to return too far. This allows the head of the screw on the spline clamp on the kickstart knuckle to hit the casing, punching a hole.

Rocking horse poo now on ebay http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=251081315734

yes it was - sorry about that- have just emptied it out

Thanks everyone for the info. Much appreciated. I now plan to put it together and do some size and geometry comparisons with a standard TY175 and will post up what I find.

The John Cane one fits neatly up in the frame under the fuel tank and works well. The electrix one also works well, but requires the coil/black box to be fitted behind the plastic sidecover and supporting it requires some thought and ingenuity to achieve. It also means the HT lead is extremely long.

No-Toil dries out and becomes not-so-sticky much quicker than normal filter oils (in my climate anyway)

It's false economy to only change the rollers. The pin and rod will also be worn if the rollers are worn, even if they look OK and someone will be having to do the whole job over again shortly. yes head gaskets are expensive, but you don't have to change the head gasket if you take the cylinder off with the head intact

maybe the points are not working? maybe the stator coil insulation has broken down? Maybe the stator coil is open circuit? maybe the HT coil has failed? maybe the killswitch wiring is shorting to earth?

why would you ever want to change just the needles and cage?

The motor ID number (M4) says 1963-1965 Sherpa N 200cc, but the cylinder head and the rest of the bike looks like M16 (MK2 Matador 250cc 1965-1967). The MK2 Matador was developed from the Sherpa N, so this bike may be a very early Mk 2 Matador. I suggest you fit an air filter before starting the motor, and get ready to stop it quickly if any of the motor bearings get noisy

Before there was "air filter" oil people used car engine oil or two stroke premix oil on foam air filters. It will work fine if you oil the filter the night before, or on the day of the ride. Not long after that though it migrates downwards, making a bit of a mess in the filter casing, and leaving the top section dry. I use a proper air filter oil mainly so I can service the air filter well in advance of the ride when I have the time available.

A riding friend had a tubeless rear rim fitted recently no problems to his TY250D (and also one to his Bultaco M198). I don't know if the rims came undrilled, or if the angle can be changed, or if the angle was fine as it came, but I do know his wheels are fine. The rims used are the type with the rubber wedge seal ring, which means that the spoke length will be different to standard Yamaha spokes. If the spoke angle is wrong the spokes have a curve in them that looks terrible and are more prone to breakage than if the nipples are at the right angle.

Reversing would be interesting

baldilocks the system OSSA uses injects the fuel in the linet tract. It is called throttle body injection. Same principle as on a Honda Montesa 4RT. Some modern cars and modern outboard motors have direct injection of petrol, where the injector sprays petrol into the combustion chamber. About why the OSSA still have an inlet port and transfer ports, is because that is how the air and fuel gets to the combustion chamber. Even if it had direct injection, the inlet port and transfer ports are needed to get the air in.

They are all Honda parts because Honda is an owner of Montesa. Maybe you are asking what countries are the various parts made in?

Yes, but first I need to know which parts of the frame I should be concerned about!

I've recently bought an unused SM Highboy TY175 frame kit. I am in the process of puting it together to ride. I have have never seen another one and am trying to learn all I can about it. The frame looks remarkably similar or identical to a Whitehawk TY175, but it has a fibreglass one-piece SM seat/tank unit rather than the Whitehawk setup. Can anyone give me some leads or info about this bike? All I have heard so far is that they have a tendency to crack the front frame tubes and that the frame was probably made by Dave Cane. All suggestions welcome thankyou photos here http://www.trials.com.au/forum/viewtopic.php?f=16&t=7408

The important things to note are It is very easy to damage the gear teeth if you use a puller that pulls on the teeth The gear is usually very tightly attached to the taper