feetupfun

This mod does not stop slipping. It is to stop the kickstart lever clamp screw head hitting the casing on return. If this is your first TY175 it may be that you are just not accustomed to the kickstart engaging at a low position. Normal engagement is with the lever just below the level of the footpeg

The brake pedal in the photo is not tweaked, it is from the "trail" kit and the tip is too far forwards for use in conjunction with the "trials" footpeg location

That's a standard TY250A brake pedal. The pegs are standard TY250A in the standard position. There was a trail-riding kit available from Yamaha that had a different footpeg location and a different brake pedal and a bigger seat

What model Ducati is it based on?

Yes you can squirt oil inside or any other way to get oil in there. Yes you can heat the outside, but the idea is to burn the gunk that is on the inside, so you need a fire happening inside. If you direct a torch inside, you can accomplish this easier. If you only heat the outside it will take longer and you will need a way to create a draft through it to provide oxygen for the fire. If you have big and small LPG torches you could heat up the shell with the big one, then aim the small one into the pipe so that air gets sucked into the pipe with the small flame and is carried through. I usually use a big oxy-acetylene welding tip and direct the flame inside the pipe until the gooey carbon starts to burn (lots of dark smoke comes out the other end and the pipe wall starts glowing dull red in a ring at the closest end to the torch). I then turn the acetylene off and blow pure oxygen in with the welding tip which pulls in air with it. I control the flow of the oxygen to control how fast things are happening inside. The glowing ring slowly moves through the pipe until it gets to the other end. Be prepared for a big bang if the conditions are right inside the pipe. Think about what is happening inside there - especially if you decide to use oxygen. No problems hanging the pipe up to do it, but if you want to move it around while it is hot, I find it easier to do it with the pipe on the ground.

It's the first 349 model and sold in 1979 and 1980. The following 349 model was the White Wonder. The standard swingarm on this model is longer than other 349s. They are not easiest trials bike to ride in tight sections, due to the motor and the wheelbase. They are awesomely good for riding up mountains.

Sounds like you are having fun. I don't know what will happen the way you are suggesting but it sounds fairly explosive. I never put any solvent inside and they burn out fine. If you have washed out the gunky oil with a solvent you may have made the job more difficult that it would have been. If you can't get it going with a torch you can always put the whole thing in a wood fire. I usually have to maintain a draft through the pipe to keep the fire going in there. Oxygen is good but you have to be careful to avoid melting the steel (and glass). Fresh air draft takes too much heat out unless it is slow velocity. A gas flame directed into one end works well to start it up

The nuts are not obvious and are 7mm internal hex drive

I put the flame through the inside with the direction of flow the same as the exhaust gases. The pipe is lying flat on the ground. After it is cooked and cooled you can tap it and shake it to remove any loose stuff. If you want to try and get the glass to flow out while it is liquid it would be best to get it to flow towards the inlet end because it will get trapped inside at the outlet end. Don't leave it sit around for long after the burn out or the insides will rust out pretty fast. Refitting it and going for a ride does a good job of coating it.

The chamber in the photos has not been opened for cleanout previously. On something like a Bultaco trials bike, cutting out a flap or hatch and butt welding it back works well because there is a lot of space between the wall of the chamber and the cylindrical mesh tube inside, and the tube is only held at the ends. On a TY chamber that technique does not work well because the internal perforated mesh is attached by welding to the outer wall very closely in many places. If you want to clean it mechanically (and I'm not suggesting that is a good idea) you need to cut the chamber in half lengthways, cut out the perforated mesh, fit the packing, weld back the mesh then weld up the chamber. I recommend burning the chamber clean. Keep it at or below red heat. Some people use a wood fire. I use either a large LPG (Propane) torch or an oxygen-acetylene torch. It should take about 10-20 minutes to do.

If it was me I'd burn it out. If you are dead-set keen to keep the packing intact, try the hot tub first. Your locations 1 and 2 would allow you to fix only the areas where the holes are cut. The chamber has to be cut in half and remove the perforated mesh to do the job properly

Sounds like the casing has pressure inside for some reason. Maybe the vent is blocked and when the motor warms up due to expansion of the gas inside it generates pressure that is not being relieved. Could also be a drive side crank seal leaking.

The main chamber has packing too. It is a thinnish layer between the outer wall and a layer of perforated steel mesh that follows the shape of the outside. It doesn't actually make much difference to the sound if the packing is functional (dry) or gooey or absent, but it is certainly a lot lighter if it is not gooey. If you heat the main chamber to a high enough temperature, the packing will change from being a fibrous mineral cloth to a glassy viscous liquid. If you do it right, the molten glassy material will flow out of the chamber. If you are someone who is fastidious enough to want to completely restore the main chamber to original performance, it is possible to cut it apart, remove the perforated metal, remove the gooed up packing and fit new packing and weld everything back together again. There are photos somewhere in the forums of how someone cut theirs apart and rebuilt it.

The thing that looks like a wagon wheel is the swirler part of the spark arrestor. It causes the exhaust gas to accelerate and spin. By making the exhaust gas spin as it moves rearwards, carbon particles (sparks) are caused to move outwards and become trapped on the outside of the inner tube, while the gas flows through the inner pipe. The wagon wheel looking thing is made from cast aluminium and will melt if it gets hot enough. The second zone of the end muffler is the muffler and to quieten the exhaust, requires the mesh to be clean and to have dry muffler packing around the outside of the mesh.

The double-chamber muffler looks interesting. How does it work?

Standard TY250A end muffler has a cast aluminium swirler inside that is part of the patented "Yamaha-Krizman" spark arrestor mechanism. If you burn this muffler out, the swirler usually melts and the motor then runs much better

The usual technique to avoid wasting money is to get the person doing the re-boring to measure the cylinder and tell you which oversize piston kit to get before you order the piston kit

Your best bet is to either ask on this forum or phone a Bultaco parts shop. There are thousands of people who know Bultaco Sherpa Ts intimately. Many of them look at this forum. There is no compiled cross-reference of model parts to refer to. The parts don't come with the part number marked on them. They did come in packaging that had the part numbers. Some parts changed during the production of a single model designation. There were some years when more than one model of 325/350 Sherpa T was released. Some models were sold for more than a year. Some parts were unchanged on subsequent models. You have a common model that will not be hard to sort out.

I'm guessing its the fuel tank vent hose. Being fairly elaborate-looking I'd say that it comes with the bike to enable it to be sold in some countries that require a one-way valve in the vent hose for emissions laws compliance. Does it have a vacuum operated fuel tap? Some bikes have a fuel tap that opens automatically when the engine is running and this could be the hose for that. Maybe it's the coolant system vent hose.

They are about $20 from Wiseco sellers

In 2010 I said they fitted perfectly. That means I didn't have to alter the piston or the cylinder or the crankcase or adjust the ring end gaps to be able to use it. One engine was a TY250B and the other was a TY250D. I haven't fitted any Wisecos in TY250 motors since then. I'm eventually going to re-bore my TY250A which is still on the original piston and rings, because I just rode a friends TY250A which had a fresh rebore and mine is a bit down on power compared to his, which usually means worn rings, especially if they are 44 years old like mine are. I'm thinking of using a Wossner piston kit this time. I'm not interested in just fitting new rings.

Here's another ventilation hole I found in a M85 frame. The wasp thought it was just perfect

lorenzo I just checked a couple of M85s for the hole in the underside of the rear loop and they both had the hole you described. My thought is that hole in the M85 frame rear loop is for ventilation to avoid problems with internal pressure during the welding process. It looks similar to the holes required for tubular structures to be safely hot-dip galvanised.

Might be the military version Sherpa T with a gun-rack (joke) They did make a Sherpa T model that had a dual (long) seat. What was your frame number prefix again? I think the dual seat Sherpa T model was prefix 221 and it would have had a seat like a model 212/213 Alpina