woody

Try John Collins at Port Talbot, JC Motorcycles. Used to be a Bultaco dealer, knows a lot about them and has a stash of used parts. May have some suitable forks. It sounds as though someone has probably damaged a fork in the past and replaced it without realising there are differences. One of the the problems of 40 year old dirt bikes.... You never know what they've been through.

Ossa MAR fork tubes come in two different lengths and the longer ones, from '76 on are too long for a Bultaco. The earlier MAR forks are shorter and may be too short for a Bultaco so make sure you get them to measure them exactly before you buy them

I can't imagine they cast different legs so I'd assume it is the tubes that are a different length. As pointed out in the above post your frame looks correct for a 190 as does the bottom clamp. What I can't figure out is the 190 tubes shown in PSchrauber's picture as they don't look like they are from a 190... The knurled part looks as though it would sit below the bottom clamp but maybe it's just an illusion. The tube in the bottom picture looks more like a 190 Overall fork length can be shortened by fitting a longer alloy spacer on the damper rod which prevents the fork legs extending to their normal length so you could consider doing this if you found a pair of longer 350 forks. With your current forks though, if one is longer than the other, the longest can only extend to the overall length of the shortest so you would still have the correct overall length, so maybe there isn't an actual problem - unless I'm overlooking something. Or, to maintain the correct head angle with 350 forks, you could machine out the shoulder in the top yoke which prevents the forks being pushed through, then just push them through to match the correct 250 length.

Not sure how well 250 length forks would work on a 350, they were shorter because the 250 frame from '76 - '78 (up to the model 190) was different from the 350, particularly the headstock position. The bottom yoke was different as well. From the M198, they went back to using the same frame as the 350.

The forks fitted to the 250 models from '76 - '78 were shorter than those fitted to the 350 models so maybe someone has fitted a 250 stanchion at some point? I've no idea exactly how much shorter they actually are.

Just love the selector drum

The wheel is the correct one, you shouldn't have a spacer between the brake plate and fork, only a top hat spacer on the inside of the brake plate. If you have that spacer between the fork and brake plate, it is pushing the wheel too far over and will have caused the damage.

On a 190, there should be no spacer between the brake plate and fork leg, the only spacer on that side is inside the hub and it is a top hat spacer, the one in the photo isn't. It sits in the bearing oil seal, top hat side facing out and the inside of the brake plated sits against it. The bigger spacer fits on the opposite side, as it is in the photo and sits inside the oil seal between the bearing and the sleeve that fits inside the fork leg. The sleeve should stick out a few mm on the inside of the leg so that when the wheel is fitted it keeps the hub away from the fork leg, although the clearance isn't much, it sits very close. The spacer on the left in your photo is wrong for a 190, what front wheel is fitted - can you post a picture as the spindle / spacer arrangement is different for earlier bikes, has someone fitted an earlier wheel? Your front hub should be conical, if it's a full width hub it's from a much earlier model, maybe another bike. The spindle nut also should sit inside the fork leg when fully tight on the correct 190 front end. On the earlier bikes the nut is visible as it sits against the fork leg. The gouge is definitely from a conical hub, but when was it done? It looks old. A problem for a previous owner which no longer exists? Post a photo of your wheel / hub

I agree, can't remember why it was changed from having a seperate pre-unit class but it makes no sense for someone riding a big pre-unit having to compete in the same championship class as one of the lightweight 2-strokes - especially on tight fiddly sections that suit Bantams, James, Dot etc. Time to give them back their own class, even if it's poorly supported at first. Competing against similar bikes in their own class may encourage others back out. This should apply to both hard and easy routes.

Surely you can get the correct one from the US? Ossaworld Ossa Planet run by Keith Lynas - he must have one as he sells the thread repair inserts and does complete rebuilds Hogans If you use any kind of sealing paste in those fine threads you may come to regret it. In my MAR, I use the copper ring from In Motion which seals fine. If the ring starts to undo itself, wire it to prevent it.

The frames for the 250 and 350 were the same for each model year, so the '75 250 and 350 frames are the same, meaning the performance and appearance of the bike are unaffected by the change. Nothing to worry about unless you're bothered by originality - no point really on a 40 year old trials bike. Frame probably got damaged, someone replaced it. Confused by what you say about documents verifying the age though. A V5? If V5 states 250cc and numbers match the bike, someone has swapped the 250 frame for a 350 frame and actually had the log book changed - a bit of a rare deed you could say...

Memory a bit hazy but doesn't a TY250 twinshock gasket fit? I'm sure I used one at some point, although a long time ago

Definitely repairable Jim, I bent a rod on one of mine a couple of months ago (over 3 years of pretty hard use, so can't really complain) and gave them to Blai at Telford. He took them back to Spain with him, rebuilt them and sent them back. Might be worth having a word with Alan Whitton? I'll see him at the PJ1 round on Sunday, so I'll ask him anyway

Jim, In Motion are the new Magicals agent

I'd guess at not enough entries to date? There is the Exmoor 2 day classic on Easter weekend, Sunday/Monday, a long established event that gets a full house of twinshock and Pre65.. That may have taken entries from this trial, people not wanting to ride on Friday, then having to travel to Exmoor on Saturday Also, people may be away Easter weekend?

They look like the 305 forks, although a set of 303 forks I had were the same as those, but I had know way of knowing if they were the originals or not. I don;t think the 303 had the reverse damping forks, but I guess some of the last models could have had them. I phoned Bill Pye to ask him about this set up but after describing the internals, particularly the long tapered rod, he said he'd never come across anything like it - from my description that is... Looking logically, the conventional looking rod would do compression and the tapered one rebound Try and get a parts diagram for a 305 as I'm sure that's what they're from. From what I can see they look to be assembled correctly

Marzocchi forks vary a lot from bike to bike and even Fantic to Fantic, especially the 305 Fantic which had compression on one leg and rebound on the other. Yours could be 305 from your comment about two different set ups. Best option is to photograph them and post on here. Someone may recognise which model they are from.

Gearing is 46:11, standard is 39:1, same as the 199a and 199b I run my 340 on 43:1 as I find 39:1 too high Bottom gear on the Motak bike (same ratio as the 340) didn't feel too low with the extra 3 teeth on the rear Frame and swingarm all standard, no mods.

Series website here - but setting it up is a learning process as they go along, so not 100% complete yet. Has the dates though http://www.twinshockchampionship.org.uk/index.html

Forks try 180cc of 10W Gearbox takes 1 litre. Any modern gear oil such as Silkolene light. If you use heavier gearbox oil the clutch may not operate so well. I use Silkolene with Barnett plates, no issues.

I don't think you can compare the Vazquez bikes with what is happening in Pre65. Pre65 bikes in their standard form are pretty agricultural and the modernisation turns them into something that is more competitive than your average Bultaco / Ossa / Montesa etc. They bear no resemblance to the original and have few of the original parts. These Spanish bikes are pretty well built to the spec that the factory gave to their supported riders as opposed to the bikes sold to customers. Blue-printed engines, properly built and set up, various stages of porting if required. Exhausts cut open and properly repacked, sometimes with a modified rear box to remove the baffles. Carburation set up perfectly, same with brakes, clutch. The chassis mods are just altered steering, if wanted, something that was done by some riders back in the day, and lowered footrests. The cosmetics, like a seat pad instead of a seat are just cosmetic. They are still all Bultaco. They look and sound like a Bultaco. It's just that everything works as it should, they feel new, tight, because they are very well built and set up. If someone had the knowledge to do the work and the skill/means to do porting, tuning the engine to how you want it, it's nothing an owner couldn't do themselves. A works spec bike if you like. The cost comes from the labour involved and the cost of new parts which are getting ever more expensive. Are they better than a 'normal' Sherpa. Yes, because of the above, but as I said, an owner could turn his normal Sherpa into one of these if he had the knowledge to do so. It's not like Pre65 where you'd have to engineer new yokes, hubs etc etc. All the parts are Bultaco, with the exception of the GasGas piston in the 280. But you could argue that has Bultaco origins.... Would it make any difference to an average rider in an average club trial on a well set up standard bike? Only in the way that it would probably give the rider more confidence through knowing that the bike will behave predictably and how they expect it too. But that's what these Spanish bikes are. Very well set up standard bikes. No specially made or expensive trick parts

The flanged type are available from Talon, but they are hard to lace up to a twinshock hub due to the length of the split spokes. Hondas aren't so bad as the have straight pull spokes anyway, but all others with bends at the hub make it a difficult job. Only ever seen it done once, on a Fantic. Be aware with the used wheels that they can suffer corrosion on the inside which can't be seen if there is a tyre fitted. I've had a couple with cracks too, but these can generally be repaired easily enough by welding.

It's there now - I got distracted http://www.trialscentral.com/forums/topic/49557-motak-sherpa-280/#entry361810

So at Yesterday's Congleton twinshock trial I had the chance to try some Sherpas, The Motak 280, A Vazquez 250 and a Vazquez 325. This is by no means a review as I only had a few minutes on each and unfortunately wasn't able to try them on any of the sections used in the trial - which would have been an interesting comparison also against my own standard 1975 Ossa 310 that I rode in the trial. I was interested in the 325 in particular to see how it compared to my own 340 which has some Vazquez mods. The 280 Motak - Very pleasant bike to ride. It pulls well right off the pilot jet and the engine responds a little more strongly than the standard 250. Not snappy at all, it's very smooth and predictable off the pilot jet and consequently riding without the clutch down to nothing isn't a problem. But open the throttle and the engine picks up revs immediately, but without pulling your arms off. it's strong but it won't run off with you. I wasn't able to give the top end full beans as it had just been fitted with a new carb for the trial and it felt like the main jet was too big and over fueling the top end. Subsequent investigation found that the carb has been supplied with a main that is too big. With the right jet fitted it should rev very nicely, based upon the bottom end performance. A very nice engine. The clutch action was good, light and with no snatch or judder. It disengaged every time, no drag, no slip, no drama, with one finger operation when it was needed. The suspension worked well, the front was soft, but not overly so, didn't top out, neither did it bottom off some reasonable drop offs. The rear Falcons worked well. Older Bultacos, even with a decent pair of shocks fitted can still feel dead at the back. These last 198/9 a and b models give good feel from the back with decent shocks and this one was no exception. I'd liked to have tried it over a continuous series of rocks for a better impression, but on the terrain I tried it on, there were no issues. The footrests are lowered and the top yoke has been modified. Fat bars are fitted with a 7" rise and the riding position is good (I'm 6' 3" and the owner possibly a bit more, hence the high bars) The steering is not altered, other than longer shocks to quicken it a little. However, the bike steered as though it had been modified and felt a bit more precise than the usual slow Bultaco feel, as with my standard 340 (same frame as this bike) Whether this is due to the combination of the footrests being lowered but only moved very slightly rearwards (as much as makes no difference) and the top yoke mod which put the rider a little more over the front, it's hard to say and is subjective, but it steered very well. No washing out, it held into the ground on full lock turns and felt quicker than standard. Even the riding stance gave the impression it has been pulled in a bit - but it hasn't. We couldn't work out why it feels like that but it's a bonus... Brakes using soft linings within relined hubs worked very well, bearing in mind also that this was after the trial and the bike had been through water a good few times. In summary then, I thought the Motak was a very nice bike, easy to manage, giving the rider confidence, thanks to a smooth but strong engine and nicely set up suspension and brakes. A credit to the owner/builder The Vazquez 250. Very similar in feel to the Motak in terms of chassis, handling and suspension. This one has had the steering pulled back a little but it felt very similar to the Motak, which hasn't. Confusing... Chassis mods are the usual Vazquez with lowered footrests etc. The noticeable difference between the two was the engine. This bike has been ported whereas the Motak hasn't. This bike is softer off the pilot jet than the Motak and doesn't pick up as quickly or strongly - this doesn't mean it's flat, far from it. It's just not as strong off pilot, but more than adequate, However, once the it starts coming off the pilot, the revs really pick up quickly and it surges to a high revving top end - a result of the porting work no doubt and similar in character to my own 340 Vazquez. In summary, another nice bike, again, easy to ride, everything works as it should and it gives the rider confidence. The Vazquez 325. Identical to the 250 in terms of chassis mods etc. I was interested to see how this engine compared to my own 340 motor. When I first got that back from having the work done, it was lightning quick off the throttle, thanks to a bit of porting and lightening of the flywheels. It had a modern feel to it as with the reduced flywheel weight, it built revs very quickly and couldn't easily be ridden at low revs without the clutch, having a tendency to stall. This 325 was very similar when delivered from what I was told and was calmed down a bit to suit our more slippery conditions than the dry rocks of Spain. The motor was soft off the pilot jet and, could be ridden without the clutch without drama. It responded quickly enough off pilot without being snappy but the additional torque over the 250 was evident. But once you are off pilot, the revs build quickly, as with the 250 but much stronger - it pulls like hell. Nice. Very similar to my 340. All three bikes were very nice to ride, all three had very smooth and predictable power delivery and had well set up motors, chassis and suspension. Of the two 250 bikes, I liked the initial power delivery of the Motak 280 as it was a little stronger and with the right main jet fitted I've no doubt would rev out very well too. The Vazquez would probably hit higher revs due to its porting, but the Motak wouldn't be far off it, but with a slightly better bottom end I'll take one of each please....