feetupfun

Here is what that original model TY175 Majesty looked like http://www.tytrials.co.uk/sitefiles/tytria...Article%202.pdf

There was another 175 Majesty type other than the two you mention. The first Majesty type had a modified Yamaha frame and looks very much like the one in the eBay photo. The frame mods were limited to the top shock mount being moved.

Paul, A current model Mikuni VM26 is nothing like the standard carby that came on twinshock Yamahas. Yes you can get new Mikunis to work on TY250 twinshocks, but don't expect to be able to buy jetting the same as what was in the TY250 Yamaha-Mikuni carby, and don't expect the needle jet, needle or throttle slide to be able to be transferred from the original carby to a current model VM26, they are dimensionally quite different. Parts for the original TY250 carbies are available. David

You might be interested in this thread http://www.trialscentral.com/forums/index....=ty175+big+bore Regards David Lahey

Ok here are the measurements for some Bultaco barrels from my shed. There were a few more that I had forgotten about. All are 71/72mm bores. All are distances from the top end of the sleeve Stamping, Exhaust top/bottom, transfer top/bottom, inlet top/bottom 27, 37/60,46/60,64/85 107, 32/60,46/60,65/91 and had finger ports 157, 38/60,45/60,63/83 86, 34/61,47/61,67/91 and had finger ports no stamping but is from my M198 and appears unmolested, 40/61,47/61,65/85 Yes I know that a M157 is not supposed to be a 250 but I'm just reporting what I saw Regards David

I can measure the exhaust and transfer port heights of a couple of Bultaco trials barrels, but am not offering to work out the timing from that nor am I offering to assemble anything to get the inlet timing The barrels I can measure at present are M198 (1977 238cc trials) and M27 (1967 250cc trials)

I believe that fuel-injected (Japanese and US brands) two stroke outboard motors are quite popular

The white with red stripe was also sold in Europe. We (Australia) got the pale blue one.

Cooktown is a great place for riding a trials bike, but is a long way from the closest trials competitions. There are trials riders in Cairns which is only a few hours drive and there is a group who ride trials bikes together and who ran one trial in 2009 in Townsville, which is about 8 hours drive from Cooktown. The major trials centres are in the South East corner of the state near Brisbane and near Gladstone on the Central Qld coast. Gladstone would be about 17 hours drive from Cooktown and Brisbane about 25 hours drive from Cooktown. You will find that long-distance dirtbike touring is very popular in the North end of Queensland and there are also very good MX and Pony Express events in the area.

If you are changing the angle at the headstock you will probably be limited in how far you can reduce the rake by the wheel or guard hitting the frame or exhaust header when the forks are compressed. If you are making big changes to the rake it might be a good idea to see what the trail will end up at before you get too carried away.

The diamond pattern looks like the pattern that would be made if the washer was gripped in the jaws of a bench vise

Some 1980s KX footpegs fit straight on but don't ask me which KX models. I just extended my standard KT pegs

Rickman did make frames for Montesa running gear and motors but I have only seen Rickman/Montesa enduro bikes not Rickman/Montesa trials bikes

If you want the standard KT bars they are available as replicas made in New Zealand (Fred and Debs KT Parts). My thing is to have 1970 bikes set up as they were at the time for comparison purposes so I use the replica bars on my KT (and on my OSSA MAR) and standard footpeg positions.

Who are the usual suppliers?

Hey tony27 you know me well I love Woody's broomstick tool idea but the rattle gun is just so fast. My record for TY250 fork seal change from go to whoa is 20 minutes with a rattle gun. I did make a tool to fit the round-with-two-flats type rod end, but soon after gave in and bought an air compressor. I'm sure the later TY250s have flats but I have a feeling that my 250A model didn't have any flats on the end of the rod. It also has the drain holes in a different place to the later TY250 twinshocks.

Haven't heard that one before Steve

26 or 28 is perfect for 250 and 325

Yes both of the tubes that go from the head to the swingarm pivot are necessary as is the stay that goes from the head to the top tube. On this bike and the 348, these components are not just to steady the head, they are to provide triangulation for the main frame loop. The other issue just means that the indent that holds the starting device on is not strong enough. Does it still have a MK11 AMAL carby?

We are allowed to use aluminium rims in pre-65 Classic trials here so there is not much call for stainless steel rims (or plated steel rims).

Some have circlip grooves, and some don't.

Mate there have been hundreds of forum postings already on this topic. Have a search and you will find what you seek.

Bultaco Betor forks were not the only 1970s forks to have vented caps. Yes non-vented caps can be used to tune the overall spring rate but beware because Bultaco Betors only have friction to retain the the fork seals so if the pressure goes too high you may cause a seal to pop out. I have been running a Sherpa T with non-vented caps and haven't had a problem yet, but that is no guarantee of anything

You couldn't be worse than me PA I tried to test ride a 348 Cota sidecar on flat damp smooth grass and could not get it to move forwards (I could go left but not forwards). Maybe it would have been easier if the passenger was not 100kg but I doubt it would have made much difference. The flat damp grass was outside the scoring tent at a popular trial and after failing so miserably in front of so many people, including the people who campaigned that outfit for many years, I have avoided trying a sidecar again, even in secret. My mate Cedric bought the outfit and the bike has been used solo for years now by his daughter Tharyn.