feetupfun

Tom I'm a little bit lighter than you at about 205 pounds and ride 1970s trials bikes. There are plenty of guys your weight successfully riding old trials bikes and yes you can easily set up the suspension to suit. Modern shockies for old trials bikes can be easily bought with a range of spring rates and with standard damping that works great. I would recommend 60lb/inch shockie springs for your weight. They come in stiffness increments of 10lb/inch. They are way better quality and performance than what came new on your Sherpa T. Falcon and Betor brand shockies are popular and suitable. I have fitted Matador springs in my M49 Sherpa T forks, and have increased the preload over standard by about 20mm and use 20WT fork oil. Seeing you are a Bultaco nut, have a rummage throught your 35mm Betor forks parts and see if you can find some springs with a higher rate. If not there are plenty of suppliers with new springs for Bultaco Betor forks. By the way, the ideal suspension sag for trials use is lots more than for speed type bikes. I use 50% sag with rider aboard and 5 mm sag without rider.

Yes you are right. The change to being allowed to stop/reverse without penalty till your foot went down did happen during the later part of the twinshock era. However being a certain age, the bikes I want to see used in competition are from an earlier time. One that springs to mind is the Cota 348. When I ride my 348 in events that are suited to stop-start riding, the 348 is hard work compared with the OSSA MAR, KT250 or any Yamaha, mainly due to the clutch action. We have a once-a-year event that is run to no-stop rules, and the 348 is just as easy to use and maybe even better than some of the others in those conditions. I'm not alone in choosing not to ride their 348 in events with modern rules, instead favouring a bike with a nice clutch. Part of it is to get a lower score, but mostly it is to be able to ride all day without being beaten up too much by the bike. I suspect that in the UK, the sections that twinshock bikes are ridden in are generally more suitable for clutch out riding, so there may not be such a divide between the suitability of different bikes there.

Have you got a decent photo of the Alpina tail-light you are seeking? I have some Bultaco electrical items including tail lights that I don't need but do not know what models they are for.

I reckon when it comes to the twinshock bikes, there are some that are much more suited to stopping than others, mainly due to action of the clutch. When the twinshock bikes were made, the rules penalised stopping, so it didn't matter what the clutch was like and those bikes were not at a disadvantage. Here in OZ, almost all twinshock competition riding is to modern, stopping-allowed rules. By allowing stopping, the bikes with suitable clutches for stop type riding have become more popular than the others. My concern is that there are lots of twinshocks that are not being used in competition, due to their being at a disadvantage under stopping-allowed rules. I enjoy riding both non-stop and stop type trials equally, but would love to see more variety in the range of bikes being ridden in twinshock class so would be happy to ride twinshock as non-stop all the time if that would make a difference.

I'm not totally sure what you are asking but it is common for a new bike to be sold in a different year to when it was made (sold as a superceded model). In the case of Yamaha twinshocks, the last model may have been constructed in 1981, but the last of the bikes constructed in 1981 might not have been sold until 1985. To me they are still a 1981 model but some people may call them a 1985 model, because they were sold new in 1985.

The answer depends on what you mean by making monoshock bikes. Yamaha made works monoshock trials bikes in the mid 1970s that were non-linkage (cantilever) type. These were not available for sale to the public. Yamaha started selling single shock trials bikes in 1984 but the design was nothing like the works bikes of ten years before and had a linkage type arrangement for the rear shock (monocross). Twinshock Yamaha trials bikes continued to be sold up until and probably even after 1984 (leftover unsold production) but while the graphics changed over time and were different in different markets around the world, were mechanically unchanged from the models first sold in 1976. 1973/74 and 1975 models are mechanically slightly different to the 1976 and later twinshock models.

It doesn't look like the standard tank for that bike. Here's a TY250 with a white TY250 tank for comparison purposes.

There are good photos of one of those cantilever OSSAs in a recent VMX magazine. From the photos there you can see one reason why that concept didn't work out that well - there is no space to fit an airbox. I can't help but think that some manufacturers had a bit of a rush of blood to the head at the time when Yamaha started selling their cantilever MX bikes and then the Mick Andrews works bike appeared and seemed to go well. In all likelyhood, the Yamaha cantilever design on Micks works bike did not work as well as the moved-up/laid down twinshock designs later seen on Fantics, SWMs, Majestys and others, due to the higher centre of gravity, greater mass and greater unsprung mass of the cantilever design compared with a good twin shock design.

Yes the wheel hubs are the same on all the twinshock TY175 and TY250 models. However there are some minor differences in the brake actuating arms and brake backing plates of some models - ie some have steel arms while most have aluminium arms and some have inspection holes in the backing plates. The differences do not prevent interchangability.

If it happened suddenly, I would guess that you have a split in the centre section of the exhaust pipe. Have a good look along the welds.

Thanks Tim. That is the most informative story I have ever seen in the mainstream media about motorbike racing. I wonder of there any lessons in that story for us regarding the popularity of Motorcycle Trials? David

Woody who do I contact about buying a replacement ignition to fit a MAR? Thanks David

The 1983 349 is better to ride and harder to get parts for so it depends on how complete and in what condition they are as to which one is better. Why decide anyway? If you like 1980s Montys, just buy both and enjoy comparing them.

I wouldn't single out Majesty parts prices on that. The prices for the Majesty fuel tanks are similar to prices for replica fuel tanks for other bikes of the era.

It's just the brilliant Aussie sunshine ScrumpyJack. This photo shows the colour better

Here is what one of the French aluminium replica tanks looks like on a 250 Godden Majesty

After the discussion on KT250 steering geometry on this string, there has been a bit of experimentation going on over here in OZ. While I was continuing to try multiple different setups with the KT forks, another Aussie just went ahead and tried fitting forks and wheel from a TY250, retaining the KT triple clamps. Soon after I heard how good the steering became, I set my KT up the same and we both think it works very well. KT purists will probably miss enjoying the visual appeal of the polished conical hub and extravagant brake arm setup but once they go for a ride, they may be won over. A word of warning though - the standard TY front guard as seen in my pictures touches the exhaust. It doesn't hit hard enough to affect the steering but does put small scratches in the finish of the guard. I'm working out what alternative guard to use. The KT in the pictures has 340mm shockies and I have also tried 360mm shockies. The bike steers very much like a TY250 now with either length shockies on it. For people with an interest in the change to the dimensions, sorry but I haven't measured anything exactly but by eyeball the front axle is about 25mm rearwards (in-line axle) and the steering head is about 25mm lower (shorter length forks) as a result of the changes. David Lahey

Steve You'll find plenty of things that will interest you in the Honda, Twinshock, Classic and SWM forums. David Lahey

I don't know what sort of terrain you ride enduros in but where I live the landscape is heavily covered with plant life much smaller than trees (regrowth, woody weeds, vines etc) and which typically whack semi-continuously against the barkbusters both sides even when you are riding along in perfect control in the middle of the track. It's not called single track for nothing. When riding in open grazing country or in desert type terrain or on a 4WD track, it is less of an issue. I agree yes if someone is hitting trees there is something wrong with the way they are riding. The person who wrote about using them on a trials bike mentioned catching on vines, not trees - easily done without barkbusters and not a pleasant experience.

Sorry but isn't that a photo of a pre-65 Bultaco Campera? The M10 Sherpa T came out later on and had leading axle forks, a different exhaust, a radial fin head and other differences that are not discernable in that photo.

If you do the rebuilding yourself, you can buy individual parts for Falcons and just replace what you want. That way you don't have to replace the shafts. The parts are not cheap though. I usually only replace the oil seals and the dust seals when I fix seal leaks on Falcons. Not sure of this is the main reason for the variability in seal life on Falcons, but the Falcon seal life can be shortened if you rely on the rubber mountings twisting to provide the movement as they rotate about the mounts. They need to rotate freely on the mounts to minimise side loading of the seal/sliding bearing. I'm happy with Falcons overall (well - happy enough to buy three sets so far) and have done back to back comparisons with the Betors that look just like Falcons and found the Betors have damping that is a bit too heavy for my liking.

I rode with brush guards on my enduro bikes for about 18 years (from when Goddard's Barkbusters were first available) so was keen to use them on trials bikes too when I started using trials bikes for setting out enduro courses in the 1990s. I did try those exact same Acerbis guards on a trials bike (TY250A). For trail riding on a trials bike they are a definite safety and speed benefit by preventing crashes due to things pushing against or catching on the levers while riding along. However for trials work, they made the steering feel too heavy so they came off again.

Here are some facts about what was ridden in our Twinshock Masters event late in 2007. Modern riding rules applied to this trial ie stopping was allowed. Fantic 240 - 1 1970s Spanish - 6 (OSSA MAR, M125, M159, Cota 348, M199, Highboy frame Sherpa T) 1980s Spanish - 3 (Cota 242, M199B, Cota 349) 1970s Jap - 10 (TY175, TY175, TY175, TY175, TY175, TY175, TY175, TL125 special, TY250, RL250) 1980s Jap - 5 (RS200, TLR250, TLR250, TLR200, 250 Majesty) 1970s bikes - 16 1980s bikes - 9 Spanish bikes - 9 Jap bikes - 15 Italian - 1 To me this indiates that at this modern twinshock trial: There was a wide range of bike ages represented. 1970s Jap bikes were twice as popular as 1980s Jap bikes. 1970s Spanish bikes were more popular than 1980s Jap bikes.

I reckon there is nothing wrong with the standard cam or actuating lever on the front of Yamaha twinshocks. I recently did the machining thing on the drum surface and on some new oversize brake linings combined with a new low-friction cable on my Majesty and the front brake is brilliant.

Who gives a fig what their bikes cost to be made rideable? I wanted a 348 for 25 years and finally got one a few years ago but it had nothing to do with wanting to have the most "competitive" twinshock but simply to be able to ride a 348 and to look at it and learn all about it. The way you are telling it, we should all ride the world's "best" twinshock - whatever that is. B*****ks! Everyone has their own idea of what they like and old Spanish trials bikes feature pretty heavily in my favourites list.