woody

It's the same as a MAR engine so the Clymer manual will cover it. The only difference is the MAR has a cushdrive on the clutch whereas the Gripper doesn't, it has a counter weight. Gearbox sprocket nut is left hand thread. The ignition flywheel may also be left hand thread, some are left, some are right - can never remember if it is the early Ossas that had left hand thread on this or the later ones - it changed around 1974. Clymer may mention it.

To be fair with the rookie rule, Yamaha, Ducati and Honda all wanted it ditched - but I take your point, the combination of Honda, Repsol, Marquez and the Spanish connection probably helped.... As for CRT, it's a joke and has achieved nothing. More bikes on the grid but for what purpose

What I did with a Pursang a few years back was to cut a pair of Bultaco rests in half and weld the half that bolts to the frame lug onto a Honda (or whatever) motocross footrest. This gave a modern wider rest which bolted to the existing frame lug. It was the best option I found for better footrests if you aren't bothered about moving their location. Used M/X footrests should be plentiful and cheap on ebay - They're usually steel off the older bikes.

Supposedly made for the home market as holiday resort rental bikes - most had the dual seat, lights and passenger footrests. I remember seeing a good few of them in Ibiza many years ago. Basically just a model 190 with sleeved down barrel to make it 175. Only difference in the frame from a 190 seems to be the rear mudguard loop which is longer like the later 198/199 bikes.

Memory is a bit hazy but it is part baffle and part tube / packing, so if you're handy with the welder it's worth cutting the back off and checking the condition inside. If you're going that far you may as well replace the insides with a tube from front to back with a single outlet. Welding them back up is the hardest job for me, I can only use a mig and it's too easy to blow holes in the thin metal. I have to 'spot' it all the way around. I hate the job.... The Jumbo is a standard Jumbo frame - doesn't look so nice in silver. The last 240/320 bikes used this frame as well and they're quite rare. They are a sharp handling bike with quick steering and light on the front - especially the 350.

The 221 model used the 250 frame with the bend in the downtube from the 190

If I can remember correctly, the SWM backbox is similar to the Sherpa clubfoot and is part baffled inside. If so, what they've probably done is remove the baffles and replace them with a straight through tube and packing, like they do with the Sherpa. Unless you're really serious and want to ring every last rev out of the engine, it's not going to be worth the work. The standard system works well on the SWM if it is in good order. They have a great sound when the system has been repacked.

The noise could be anything, primary chain, weight catching the casing, main bearing, big end, piston… Your movement on the crank could be a loose weight as they can work loose. Take off the ignition cover and see if you can detect any play from that side. You should definitely detect play up and down if there is any in the main bearings. If the weight is loose and is catching on the cover, just re-tighten it and try again. The weight is held on by a type of allen bolt (odd size but can’t remember what – 9mm maybe) You can shove a thick rag inbetween the chain and sprocket to jam the clutch in order to re-tighten the bolt. It should have a lock washer under it so may be worth removing it to check first. You will have to replace the casing to start the engine as if you don’t there is nothing to support the shaft and you may bend it with the compression the 350 Gripper has, but anyway, without the casing fitted you won’t know if it is catching. If the chain is worn, it will have to be replaced, there is no tensioner on the Ossa. If it is very badly worn it will score the casing with the excess movement it has. Replacement is fairly easy and involves removal of the complete clutch as you have to fit the chain to the sprocket and basket and fit onto the shafts together. As above use a thick rag inbetween the chain and sprocket to jam the clutch to undo the weight’s allen bolt. To undo the nut that holds the basket put the bike in gear and lock the back wheel which will stop the gearbox shaft turning when you try and undo the nut. The weight just slides of its splined shaft. When you remove the weight there are two semi-circular thrust washers behind it and these will fall out. Use grease to hold them when you refit it (can be fiddly) Once the weight is off you can slide off the crankshaft sprocket but it must be done together with the chain and basket/hub. The hub may be a tight fit on its shaft and need a bit of persuasion. If you don’t have suitable pullers, you can use tyre levers to lever behind the basket which will bring the hub with it but obviously be very careful what you lever against to avoid damage. It shouldn't need excessive effort. The basket sits on a sleeve with a thrust washer and spacer behind it – these should remain on the shaft but make sure they don’t get dragged off with the basket. Refitting with the new chain is a reversal of the above. If you still have noise then you’re going to have to look further at other components such as piston, mains etc. Check that the bashplate isn’t touching the engine underneath as the vibration this causes can make noises that sound like worn components. I once had this on a Bultaco and all that was happening was that the engine was vibrating against the bashplate. It sounded like the engine was falling apart…

Gilles Burgat after geting stretched, forgetting how arm-wrenchingly powerful the Jumbo was Or Bernard Cordonnier

Gollner KT was yellow, Gollner Ossa was something else.. Blue maybe? or just white/green as normal. No-one did a yellow one as far as I know, probably just altered by a previous owner. Or maybe a dealer's colour for a supported rider (I'm assuming you didn't buy it new, otherwise no need for the question...)

Thing is, what would you want to do with it? A rare bike the Fraser, it would be a shame to do anything to it to spoil its original look and design. And whatever mods you do to it, it will never be as competitive as an 80s bike. In standard trim, it would be a bit of a handful in some of the Normandale rounds but someone of your ability could hustle it though a lot of the sections and make a reasonable fist of it, but not the ideal choice of mount. Modifying it I believe, wouldn't make much of a difference, just spoil it. Barry Roads will give you a better idea of what to expect on that bike - I can imagine his face when you ask him... I rode a KT in some of them - it will do the job but obviously harder work than a modern t/s and the KT would be an easier ride than the Fraser.. Best option is to choose the events you ride it in. The Miller series woould be ideal as the sections would still present a challenge on that type of bike but none would be unmanageable. There are two down your way to the end of the season - North Berks and Perce Simon. Then there are the club level classic events, as mentioned above. I'd leave it as is, a nice piece of history and rare, just pick the right events to use it in.

That's the problem I found when trying to set up my Jumbo clutch. The actuator travel is generally not enough to allow the plates to clear properly, therefore they can drag. If you adjust it to clear the drag you can get slip in the higher gears or even 3rd and 4th if you're howling it in sections. The clutch is also slow to take up when it is like that. They're a real pain to set up and vary from bike to bike. Lengthening the arm makes it lighter in action but worsens the affect on the actuator as you need more travel on the lever to clear the plates. I think there are 3 different actuator designs with different size ball bearings (at least there are for the Jumbo which uses a different clutch case) Best fix on the 'ordinary' models is to fit the clutch case from the Aprilia with the external arm which gives a much better action and solves the problem. Unfortunately, that wasn't an option on the Jumbo due to the different case design. The actuator design inside the clutch casing is awful.

As long as you measure everything up properly so you know where to make the cuts, yes it's a viable conversion. Pitfalls are cutting in the wrong place.... You have to get the angle just right on the front downtube to mount the D shaped bracket and make sure there is enough clearance under the engine. That's probably the trickiest part. The rear is easy enough.

Looks like the shocks, footrests and head angle have been modified Better? It's subjective and impossible to answer without riding back to back with a well set up standard bike. Modernising older bikes doesn't always work well. My 340 has a steepened head angle and there is a trade off. It steers quicker and is easier to manage in nadgery stuff but it's lost its stability and is very twitchy.

There should be a ball bearing between the pushrod and the 'mushroom' that acts upon the pressure plate. The fact that you have no thread left indicates the ball bearing may be missing.

If you do a search on clutch adjustment there are two or three seperate articles on how to set up the clutch from a while back. Shouldn't be too hard to find

No it hasn't, it followed the rule change back in the early 80s when stopping and hopping became allowed. The trial got steadily harder and the sections less flowing. Numbers dropped to a point where the trial was in collapse and the organisers were asking people to come and ride. It went back to no-stop in '97. Within 3 years it was over-subscribed. I guess this was the theory applied to BTC which had become so difficult only 3 riders could make a reasonable attempt at the sections whilst the other 6 struggled. Return it to no-stop, reduce the severity and attract more riders to get the number of participants back up again seems to be the intention. Whether it will achieve that time will tell. Ultimately, it depends on what is required of a BTC as to how you measure its success. Is it for riders (like it used to be - people watched out of enthusiasm for the sport and that amount of enthusiasm doesn't exist any more and I can't see arena type venues requiring an entrance fee getting it back) is it for spectators or is for promoters to make money out of. Each of those objectives would have success measured differently. As for rules, I much prefer no-stop as it is a far more pure version of trials and to me what the sport is about. One chance to get it right, not to be allowed to stop, re-align and have another go. But I'm not convinced it will solve anything at BTC level. I don't think there is any more a problem with observing no-stop than there is stop allowed. It is equally possible to be erratic at either and I've seen many rides get away with fives under stop allowed when they have clearly gone backwards. No-stop is no less or more difficult to observe / enforce now than it was 40 years ago. But does it now fit BTC. Is it what riders really want and will it increase the numbers taking part. That is what this year's experience should establish.

Will this be coming out to play in any of the Miller rounds then Martin Be nice to see an old Cota being used

Cancelled due to lack of entries

Cancelled due to lack of entries.

I walked past one parked up at a section and didn't notice it, thought it was a Beta with no graphics... And no, I'm not criticising the bike as I haven't a clue how good they are. In appearance, I just didn't think it stood out from anything else (makes no difference to me, but that matters to some)

Two ways of looking at putting the air-cooled mono engine in a twinshock. One for, one against. Against - it is post twinshock era therefore shouldn't be allowed. For - reed valves have been around since the early 70s and were fitted to Yamahas (and Suzukis I think) as standard, Ossa UK were fitting them to the MAR as early as 1974/5. Many privateers fitted reed valves to their twinshocks. Therefore there's nothing wrong with someone fitting a reed valve to a twinshock Fantic. By the same reasoning, you may as well save yourself the engineering work and/or cost and just fit a later engine. Same result, different means. Personally, I don't think it is worth it. There is nothing, in any of the classic events I've ridden anywhere, that a standard 200/240/300 Fantic would be stretched on - or any other of the later twinshocks. They're well in their comfort zone and nowhere near the limit of the bike's performance. The trials are nowhere near as hard as the BTC and WTC of the day, so how can they be. I've always felt that the 38mm forks, later engines etc. aren't worth it as they don't give any real advantage in the events in which they are ridden. A standard bike will easily cope with the sections - in the end, it's down to the rider. Converted monos are a different thing altogether though. Personally I don't see the point or the attraction of a bike that never existed, other than looking for a performance advantage. I don't understand the 'I want to ride twinshock trials'. thought process. A trial is a trial, I'd have thought it was more a case of I like such and such make bike, for whatever reason (twinshock, modern, air-cooled mono) therefore you get one and ride it in whatever event is suitable.

Converted monoshock - therefore not elligible to compete in the twinshock class in Normandale or Sammy Miller series In club trials, it's up to individual clubs whether they allow it to compete in their twinshock championship class (ie: allow a rider to use it but not be elligible for their championship) They are a 'nothing' bike. They never existed when new so no-one has any affinity for them, never rode one when they were new or aspired to own one (because they never existed) Built purely to get the biggest machine advantage possible in the twinshock class, no other reason.

Just don't see the point The 305 was as good a bike as you could get at the time, if not the best air-cooled mono. It works fine as it is. If you're riding it in an air-cooled mono class, the whole point of that class is for bikes built during a certain period and for the spec of those bikes. Change all that and it is no longer a bike with a spec from that era. If you're riding it it modern events it's a different matter but to compete against other air-cooled monos, you're drifting outside the purpose of having a class for an era of bike. Personally I don't get why people want to do this. Presumably, old bikes are bought because their owners have some kind of affinity for them, used to ride them or wanted to but couldn't afford one at the time. So why buy them now and then try to change them into something else that they weren't - may as well buy something else to start with. Same with twinshocks. Only my opinion of course. Your bike, so up to you what you do with it.

That wasn't my intention, but see your point, only intended as a tongue in cheek comment for a bit of fun. Definitely don't want to provoke another 'discussion' on stop/no-stop on here, that's doing quite nicely on the BTC thread.... Don't really pay much attention to the WTC or BTC these days but yes, agreed, nice for them to get a decent result.