feetupfun

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

The early 5 speed casing is not the same as the 4 speed casing because the 4 speed has a large indentation for access to the bottom engine mounting bolt and the five speed casing does not. I don't know what it is like where you live, but here the cover that suits your motor is quite commonly available, probably because they were also fitted to the most popular (early to mid 1970s) Alpina models, which are not popular nowadays (compared with Sherpa Ts and Pursangs) so there are lots of Alpina motor parts available. I'm pretty sure you could buy one from any of the Bultaco parts suppliers. The later type (1975 on) has a different shape to yours internally and I suspect would not fit over your crankshaft flywheel

How much riding did it take to break those frames? I'm trying to decide if I should do some reinforcement before it gets replated.

What other help do you need?

Problem sound more like carby to me (maybe pilot jet blocked) Depends what you mean by proper Sherpa conversion Sprockets available from Bultaco parts suppliers in Spain, the USA, UK and Australia and probably many other places. One supplier in the USA is located in New York State and I'm sure of you google Bultaco Parts you will find them Your 115 Alpina is quite removed from the 1974 Sherpa T in design. The first model Alpina is much closer to being a Sherpa T than yours. At the bare minium you need Sherpa T triple clamps of the type to suit your fork tops to get the steering to work. Alpina gearbox is OK for trials if you get a big enough rear sprocket, but top speed will be low. Your brake hubs are heavy compared with Sherpa T and the tank is bulky. It all depends how good you want it to be for trials. The VIN codes just say it is a M115 Alpina which means it is the second generation of Alpina and is a 250cc. Your codes do match - PB means frame number and PM means motor number

The reason bars are made a bit wider than the average person likes is because they want to sell as many as possible. If they made them to suit the average rider, then people like me (with long arms) would need to buy something else. You can easily shorten bars but lengthening is not as easy

The design of a motorbike gearbox is such that any clutch drag will load up the gear dogs when the bike is stationary. It is impossible to prevent clutch drag completely but it can be minimised. The important things for minimising drag are: The steel plates are flat The steel plates are rough The oil is the right viscosity The disengagement travel is sufficient The springs all have the same rate and preload (the pressure plate stays flat as it moves out) The fingers have smooth edges The hub has smooth splines When you are moving the shift lever, do it in a way that you can control how far you move it. I often use my hand to find neutral so I can control the movement of the shifter better.

You won't like the steering so much when the front tyre hits the exhaust pipe or the frame tubes every time you load up the front end

The engine design, being Yamaha is very sound, but that may not be the most important thing in a bike that is now 19 years old. How it has been maintained can mean it might be fine or it might be knackered

If you do a search on these forums you should find my posting showing the construction of a puller for the primary gear The sprocket is easily removed using a cutting disc in a 100mm angle grinder The cylinder nuts sometimes need to be drilled away to get the cylinder off. Heating/cooling and leaving them to soak for a while with a good nut release liquid may avoid the need to drill the nuts/studs away The subject of working on 348 motors has been covered many times on these forums so you should have plenty of guidance by the time you have read previous correspondence. There is another thing with Montesa motors to remember. The side float for the crankshaft is managed with shims inside the crank seal carriers. A common mistake has people bending their crankshafts due to setting them up with negative float during reassembly. Standard gasket thickness is 0.5mm for seal carriers and gasket between crankcase halves Please keep us up to date with how you go with the motor. Disassembly order: Exhaust off Leave motor in frame Sprocket off Head off Loosening agent on cylinder nuts Oils out of both compartments Kickstart off Magneto cover off Ignition off Carby off Shifter off Primary drive cover off Primary gear nut loosened Clutch off Gear shift mechanism off Primary gear off Loosen crank case screws Undo cylinder nuts Take cylinder off Remove piston Take motor out of frame Separate case halves Remove bearings from near the weld repair

Yes removal of the primary gear from its taper is a special challenge, and the sprocket on a 348 is also on a taper and is usually very hard to get off. The cylinder nuts are also an unusual size (7mm internal hex), and usually bound to the studs with corrosion so for your first two-stroke crankcase split, you have got a bike with extra challenges compared with the majority of bikes. I suggest that if you are only splitting the cases to get the case welded where the kickstart makes a hole, then plugging the hole some other way is a practical alternative. The hole in my case was sealed with silicon rubber about 12 years ago and has not been a problem in any way since then. I have another case ready to go that has been welded up to repair the hole, but nothing has gone wrong with the motor in that time so it remains a spare.

check power is getting to fan, if yes check fan motor on a battery (12VDC) if no power getting to fan, check fan switch and power supply from rectifier

Some actions (usually within a turn) in mototrials can really load up the steering. Straight ahead is usually not an issue. The ideal width is usually the widest that still allows the rider to use full steering angle in all positions.

The sparkplug appearance shows the combustion conditions at the time that the motor stopped firing. If you want to read the sparkplug to check on the mixture at full throttle, you have to stop the engine while it is running on the main jet. Just because the fan starts and stops normally, that is no reason to think that the motor is jetted correctly throughout the range of throttle positions. The fan responds to coolant temperature, which lags changes in the heat production rate. The thermal inertia of the cylinder and coolant is the cause of the lag. If the lean mixture only cause brief periods of increased heat production, then fan operation will appear normal.

Yes if you fill the coolant system to the brim it will eject some coolant out through the overpressure valve as the coolant expands with temperature rise. I'm only guessing here but maybe for some reason your motor is getting hotter than normal when you wheelie, but you haven't given any details of what sort of wheelies you are talking about so it makes remote diagnosis difficult. One thought I had was that maybe your radiator fan runs backwards, and the only time your bike is ridden fast is during a wheelie, so there might be little airflow through the radiator if the fan starts while you are going fast? (fan working against the natural airflow ditection when the bike is moving fast) Same for "big climbs" are you talking 10 minutes or 10 seconds of continuous climbing? Fuel coming out the overflow usually means either a passing float needle valve, or the fuel level set too high in the float bowl. If it only comes out when you are riding, the level is set too high, or the overflow standpipe has a problem. If it comes out when the bike is completely stationary ie motor stopped and bike upright and sitting on a stand, it is a passing float needle valve. If you can leave the bike parked with the fuel tap on, and there is still fuel in the tank (and not on the floor or in the crankcase) when you come back to it, the float needle valve is working fine.

with the carby upside down and the gasket in place, measure from the upper surface of the gasket to the top of the floats