feetupfun

Some (not many) MK4 Matador components are shared with Alpina and Frontera. I would say they are no more or less valuable than any other early 1970s Bultaco.

Depending on the price of a new basket, it may be cheaper to pay someone to machine the finger edges flat with a milling machine. That would be about 30 minutes work on a milling machine

Yes I've done it but it was a few years ago so the photos will be a fair way back in the forum. It was the first time mine had been apart. One of the boxes had metal wool packing and the other was mineral fibre. Can't remember which was which. I used mineral fibre in each and made new perforated tubes for one of them. Mine didn't run any better after the repack but was lighter and quieter. I notice that later model Montesa trials bikes of Spanish origin had a much longer header pipe than the 348 which may mean that having the front section packed at the right density where it is in contact with the perforated tubes could be important.

YZ125C and YZ125X had this cover

I just bought a bike that had been sitting for 15 years straight with the clutch lever held in with cable ties because the owner didn't like it to stick. The clutch works perfectly

If they have falcon springs, the rate is usually engraved on one end of each springs, on the flat bit. They usually have just the first digit ie 5 for 50lb, although I have some that have the full number 50 for 50 lb. If there is nothing engraved you can work out the rate using a coil spring calculator of which there are many available free on the internet. Falcon springs are not colour or finish coded. Standard used to be chromed and now standard is powder coated black.

I'm not sure of your question. It shouldn't matter how much free play the arm has. Are you saying the cable inner is too long?

http://www.southwestmontesa.com/production.html This list says 250 Enduro and the first 3853 of them were made in 1974 so your number looks like 1974

Two stroke trials bikes are easier than two stroke MX bikes because they don't have power valves

Yes Maybe Maybe Hard to tell from your description what is causing the problem. Could be lots of things

OK first i want to clarify that this forum string is about TY175 footrests, which attach to the frame completely differently to TY250 footpegs. It sounds like you are asking here about TY250 footpegs, As for what a bike does when you blip the throttle, it is pretty much impossible to communicate bike response like that on a forum, in words. I can say that if you are sitting down and riding along flat ground in fourth gear, a combination of weight transfer, throttle position and clutch dumping will lift the front wheel high enough to get to the balance point. If you want to do a balance point wheelie in fifth gear on the flat you will need to be standing on the pegs to get enough weight transfer. They are about 16 horsepower. So much of what a bike does is determined by what the rider does with their body, that your question needs to be a lot more specific to be able to be answered. Keeping the front on the ground or floating around off the ground is something the rider controls, no matter where the footpegs are. I have no idea how the tyres I use are made. I remember that radial ply rears (AVON) came out in the 1970s and competition tyres have continued to improve since then. I run IRC tube type and Michelin X11 tubeless type rears with a tube on my twinshock trials bikes and they work way better than 1970s design tyres.

I've previously bought a new threaded insert from Keith Lynas in the US made from aluminium and then locally had the hole in the cylinder machined out and the insert welded in place.

Zinc-rich-primer (used for painting welds on galvanised structural steel) usually has a matt finish that is pretty much impossible to keep clean. I paint my frames with automotive lacquer for the same reason you mentioned - it is very easy to touch up the inevitable scratches, but it looks good, unlike the zinc spray paint

The 116 is the first 350cc Alpina model and it has a longer stroke than the 99 Alpina. The 99 may have been marketed as a 350 but is 325cc. Bultaco introduced "choice of shifting side" during the following series of Alpina (137/138). Some 137/138 are RH shift and some are LH/RH shift.

If you have the original rear rim on your 74 TY250, it will have a bead seat that is suitable to use with a tube and a modern tubeless competition trials tyre made by Michelin or IRC, or a modern tube type rear trials competition tyre made by IRC.

The only 325cc "350" Alpina was the very first "350" model and that is the M99 from 1972/73. All the "350" Alpina models that followed the M99 are 350cc (with the longer stroke). The M99 is the only "350" Alpina that shares frame and steering geometry with the Sherpa T of the same period. All Alpinas after the M99 "350" and M85 "250" share triple clamps with the Pursang/Frontera instead of the Sherpa T triple clamps. Some Alpina models also have a longer wheelbase than the Sherpa T of the same period, courtesy of a lengthened swingarm (M137, M138). Every model Alpina is a delight to ride. They all have light handling and incredibly good steering. The Alpina models after the M99/M85 have a bigger and much stronger front brake (shared with the Frontera).

I tried notoil but then went back to Silkolene because the notoil lost its stickiness after a couple of weeks. It is quite hot and dry here so it probably dried out faster than somewhere with a more temperate climate.

A stainless steel welsh plug does a good job for the oil pump hole

Sounds like you might have ridden something newer since then

The foam is "open cell" which means that what you see is actually like a skeleton of strands with random shaped pathways in between. The air flows around the strands in the skeleton because it is a gas. The dirt particles tend to travel in straight lines and will hit the skeleton at some point. To prevent dirt particles from working their way through through the foam, the foam skeleton needs to have a thin coating of oil on it all the way through so that the dirt particles will stick to it when they hit it. If you put too much oil in the foam, you will cause drag for the air by blocking some of the pathways (which will reduce the maximum power available from the motor) If you only put oil on the outside of the foam, then if any dirt particles which manage to get past the oily outside of the skeleton before hitting a strand will go through the foam and out the other side. Filter oil comes in spray cans and in bottles. Spray cans are probably a better idea because air filter oil has some light and fast-drying components that allow you to work the oil through the foam then evaporate off, leaving just the right degree of stickiness. Being a spray can, the contents are only exposed to the atmosphere after they come out the spray nozzle. When you buy filter oil in a bottle, each time the bottle is opened to get some oil out, some of those light and fast drying components evaporate from the oil in the bottle before you seal it back up again.

How long have you had it? Are you sure it is actually going into gear? My 348 requires a special technique to get it fully into first gear. If I don't do it, it goes back into neutral while I'm riding.

When I had the VM26 on it, I added a bush on the inlet bell to fit the standard Montesa connector to the airbox. With the OKO fitted it did not need a bush on the inlet bell, or stretching, to fit the standard airbox connector and it fits the connector to the cylinder which was from In Motion. If you are asking that question I'm wondering if you have read the info about fitting one to a 348 on the Mid Atlantic Trials website? My jetting is whatever it came with from Mid Atlantic Trials. I didn't pull it apart and haven't needed to pull it apart.

To answer your carby question, I've had a 26mm OKO on my 348 for a couple of years now and it works very well. Prior to that I had a VM26 Mikuni on it which was also good.

If it is a 360 Pursang cylinder then the cylinder will be longer than a 325 Sherpa T cylinder because 360 Pursang has a longer stroke. Yes the sleeve (and the barrel) could be machined shorter at the bottom to make the piston crown the right height for the cylinder, but the port timing will be wrong

Mine mount onto the frame exactly the same way as the standard peg mounts