woody

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.

So it appears the BTC running no-stop haven't hurt his performance in the WTC stop allowed events then....

I'd imagine the cost of booking that in as a proper job with an engineering firm would be hugely expensive. The set up time and machining time etc. You may be better off buying the top yoke that will take the fatbars from Yamaha Majesty.com - assuming your bike is a TY175 that is. There's no real advantage having those bars though, a lot of expense for no gain. Unless you just like them of course which is a different matter, then no other reason needed.

Jet numbers for one make of carb don't always correlate to another. 145 would be a massive jet in the Dellorto. eg: The 350 Jumbo only used (approx) a 95. My 340 Bultaco with Dellorto uses 98. My 325 Bultaco with an Amal uses about a 150. My other 340 with an OKO uses a 115 I think

On the Dellorto yes, fuel screw

These are the Dellorto settings from my 340 Bultaco Pilot 40 Main 98 Needle tube AV264 Needle X2 Slide 4.5 Very similar. I don't know which is the weaker needle, X2 or X1 but your slide is very weak at 6.0. Maybe that is most of the problem for running weak. I can't remember the settings in my Jumbo now as I no longer have it, but the main jet was definitely not bigger than 100, so I don't think your main jet is the problem.

The ignition is the same on all the Sherpas from the first 5 speed models, so you can swap over no problem (never had a 4-speed so didn't want to commit to including that...) I remember the M159 '76 Sherpa as being very quick in its power delivery after the earlier models. The later bikes seemed to be a bit softer, more like the early models. I have a M92 325 which is soft but pulls like a train and would probably pick up a lot better with a new carb (still on the original well used Amal and everything else...) I agree with ND on the electronic. It won't make the bike develop more power, or run or pull any better than good points. There is a lot of hype over electronic. What it can do is get the engine to rev a bit more due to the advance curve they can build in. I have a Motoplat on my 340 and it revs like hell (also has a tiny bit of porting and exhaust baffles removed, but I suspect it is more down to the ignition and spot on carburation) You also get a bit more peace of mind with electronic when submarining through water... And no maintenance issues. But more power - I don't believe you do, but just personal opinion.

You're going to an awful lot of bother for little gain, if any, to be honest If you compared a 325 and 340 motor back to back, without being told which was which, chances are you'd not tell which was the 325, which was the 340 (power that is, gears excepted of course) You may as well just fit the ignition to the 340 engine and use that. If you want a 6 speed with 325cc, easiest thing to do is fit the ignition and 325 top end on the 199b engine, but the 199a crank will fit as well if you want to go that far. The crankcases are very different inside the gearbox for the 5 and 6 speed. I'm no engineer but I don't see how the 5 speed could be altered to take the 6 speed cluster..