feetupfun

for what it is worth, the motor in the Majesty video is a 320

For second hand parts ebay is good New parts: In Motion Trials in the UK and South West Montesa in the US For more detail you might have to say what parts are you needing and where are you located

Another thing to consider is the (lack of) corrosion protection provided by running weak premix ratios and synthetic premix oil. Semi synthetic premix oil is better for protection from corrosion.

and all I can tell from that photo is that it is probably a post-1972 model 247. The tank/seat is pre-76 but that really doesn't say much because it is common for 247s to have the wrong year seat tank fitted. A photo showing the clutch cover and knowing the engine and frame numbers would help with the dating process What is the silvery looking lump on the front downtube?

Those rims are for tubed tyres The second plug hole can be used for a decompressor. Some people used them back in the day It is also possible to use the second hole for a sparkplug suitable for riding on the road. Quick change over of the cap when you go to ride trials again without any tools needed.

yes swapping yokes is probably easier than making changes to the frame, but it can't achieve the desired result. Apart from the theoretical reasons I have already posted, evidence for this is that if it worked, fitting different yokes to twinshocks would be a popular modification. What is popular, is fitting the forks and yokes from a later model bike, which improves the action of the front suspension. Making the steering more like a modern bike requires a steeper steering head angle.

All you do by altering the yoke offset is to change the trail and the wheelbase, does nothing to the steering rake angle. Steering rake is the angle of the steering head, not the angle of the fork tubes. If you increase the trail by using different yokes, you will need to move the axle forwards (ie use leading axle forks) to regain a decent trail dimension. Eccentric sleeves in the steering head or on the steering stem are used on other bikes to adjust the steering rake, but I suspect the Ty175 steering head is too small a diameter to fit eccentric sleeves. Another issue to consider is that if you just make the rake angle steeper without also moving the steering axis forwards, there will be clearance issues with the front mudguard on the frame and exhaust. Another issue with just steepening the rake angle is that you will shorten the already-short wheelbase

ACM has been going for two years now in Australia and the experience has been very much as old trials fanatic has already described, including the lack of Fantics. We run them on the same line as the Twinshocks. I would like to add that I would not count on too many new people coming to ride "old-bike" trials because of ACM class, rather it is riders who previously would have ridden Twinshock or Pre 65 who are riding the Air Cooled monos. I suggest you have a later cut-off than 1990 so that Yamaha Pinkys can ride.

does it really lock up the gearbox, or is it just dropping into gear?

I stopped watching FIM trials many years ago because for me, stationary trials bikes are boring to watch. I am very glad that there is going to be no-stop riding in the FIM events and will probably now start watching them again.

I haven't needed to do it because I prefer IRCs, but a friend has done it to the rear rim of his MAR and it worked for him with a X11 tubeless. I have also seen a posting that says you can grind away the inner edge of a tubeless tyre to get the same effect. I think I would prefer to grind the rim because you then only have to do it once

or use the same angle grinder to reshape the bead seats of the rim so the Michelin stays put

The postage is also pretty amazing (expensive)

The fluid only dissipates a miniscule amount of heat compared to the discs and calipers. There may be higher boiling point fluids available, but even if you raise the boiling point, the discs will just get hotter and melt the pad surface (losing their frictional properties) and maybe also catch fire. Bigger disc brakes as fitted to enduro bikes would work well for the sort of riding you do.

or fit a tubeless rim

I bought a TY175 that had DT front forks (in-line axle model) on it and they had used a brake plate which fitted both the DT fork leg and the front wheel, which is from an IT125, but has the same drum and axle dimensions as a TY175/250 front hub. If yours are in-line axle DT forks, you should be able to use the brake plate from an IT125 (or possibly DT125 E) for your DT forks and TY wheel. I fitted TY forks and TY brake plate to that bike so I'm happy to sell the brake plate that the bike came with.

oversize pistons usually have numbers stamped on the crown indicating the size that piston is bigger than standard size. The numbers could be imperial or metric values. If it says 010 it would usually mean 0.010 inches over standard size. If it says 25 that would probably be 0.25mm over standard size Pistons made for Yamahas would usually have the piston oversize in mm units Standard size pistons do not usually have size numbers stamped on them Sure-fire way to work out if it has been rebored is by measuring the bore diameter No idea what the > might mean

Welcome to the forums Steve. Please post photos of your Montesa when you get it. If it is from 1970 it will be a 247. If it is a 242 it will be 1984-86.

possibility 1 - when you put the carby back on you might have aligned it slightly differently with respect to vertical compared to before you took it off possibility 2 - maybe there was something holding the float valve open and you cleaned it out when you took the carby off

I have a lovely 1968 M49 so am always interested in other peoples M49s. I was pretty shocked and speechless initially with you making a tailpipe using plumbing parts, but accept that everyone has their reasons for why they do things. You did ask for feedback though so here is my 5c worth: The main section of the exhaust is probably not made of copper. Maybe it has been repaired using bronze welding which made it look like copper. Those mufflers are usually made of pressed steel. I can even see the weld along the seam on yours so it's probably just a normal Bultaco item made of steel. By using such a long tailpipe of such small internal diameter, combined with the 45 degree elbow and the steps in internal diameter that accompany the use of BSP plumbing fittings, you have probably created a design with more resistance to flow than the original triangle muffler. The piece of 1/2 steel pipe and the gal elbow with the super trapp on the end will put a lot of load on the end of the Bultaco muffler when you ride the bike on rough ground so probably need to be supported from the frame somehow. That is a pretty cool idea to use that super trapp muffler and I'm wondering what it came off. I haven't seen one with a 1/2 BSP thread on it before and was thinking maybe it came off a Briggs and Stratton stationary engine because they have a threaded exhaust port. One thing about the Super Trapp is that because the gas comes out all the way around it is hard to avoid the exhaust gas overheating things in line with the louvres. I managed to melt the edges of a few rear plastic guards when I had a super trapp on my 4 stroke enduro bike in the 1980s. I figure that might have been why you relocated it from where the previous owner had it mounted. Another way around the heat problem is to fit a heat shield part way around the outlet of the louvres. That did work for the heat problem, but after the super trapp fell apart for the fifth time despite reinforcing all the bits that failed previously, I put a normal muffler on. A super trapp on a M49 will have a much easier life than on a 400cc hotrodded 4 stroke enduro bike so it probably won't self-destruct for years. An alternative way to fit a low resistance tailpipe and muffler is to use smooth bore steel tubing of approx 22mm ID leading to an absorption muffler supported from the rear frame loop. If you need it to also be a spark arrestor, then something like a TY175 or TY250 muffler would do the trick. That size tubing should fit inside the shockie, and additional clearance for the tyre if necessary could be gained by making the tubing flat-sided where required. Regards David

Where I live most motorbike shops have that needle and seat set on the shelf

el cheapo chinese 240V approx 15 litres tank

You take the bits off that stop you seeing the frame and wheels, like the tank, seat, exhaust, mudguards, airbox and leave the wheels in place, then sight from the front and rear from all heights. Common frame bends with Sherpa ts are: Front end of frame pushed to one side or twisted at an angle to vertical or both Swingarm twisted (one side higher than the other) Swingarm arms pushed to one side (symptom will be rear wheel not in middle of bike) Front and/or top frame tubes curved (from frontal impact) Tubes under motor curved from banging on things

I'll bet the builder assembled the case halves with the crank seal retainers in place

Michelin rears $180-$200 IRC rears $150-$180 depending on Tube or Tubeless type