woody

It depends where you ride, so there is no definitive answer. Different clubs have their own ideas of what are acceptable, some don't have guidelines and are pragmatic about it, as long as no-one turns up with a GasGas front end. I think you are pretty safe anywhere with the billet yokes that various people supply as the pinch bolts are inside the stanchions and can't be seen anyway as they fit from the back. These seem to be acceptable for the clubs that have the most stringent rules, Red Rose, Yorkshire Classic and Pre65 Scottish. If your yokes don't meet the criteria you just go in the specials class (not the Scottish obviously)

Thanks Rob. I definitely don't have one of those. Whatever was fitted to mine, some kind of case saver, I haven't found yet as not had time to look. Next question now... Your sidestand. Is that the usual way they are fitted? Mine came with some sort of U shaped steel bracket attached to the kickstart when I bought the bike, although neither was attached to the bike. I assumed it was some kind of 'fix' and that the correct bracket had broken off the swingarm. Is that one on yours the correct bracket or is that something you've fashioned. It's neat, whichever. Mine has no holes in the swingarm where your 2 screws are. And finally... have you done anything with your clutch or is it standard. Maybe you're one of the lucky few who has a decent Rotax clutch operation. Mine is junk. I really like the bike, the engine torque is phenomenal with the reed fitted, but the clutch ruins it. I've just fitted Barnett plates (they work really well on my Ossa and Bultaco) but they've made no real difference. It still graunches and judders if trying to slip it in 3rd or above and it's almost impossible to get it light enough for one finger without it slipping on initial take up. Back it off to cure the slipping and it won't fully disengage and creeps. I'm going to start from scratch and set it up again before the weekend to try again, but just wondered if you had done anything specific to yours to make it work, or do you just put up with it. I'm getting to the point where I'm thinking about getting someone clever to fit me a different clutch in it.

Just bought it from one of the ebay sellers, can't remember which one as I've bought a few over the last couple of years, some based in UK, some Taiwan. Never had a problem with delivery from either.

They all use the same size (well, from model 49 definitely, I've never had a model 10 or 27) The Pyramid bearings are a straight fit as they are the correct size. You only have to machine the alloy head top nut if you use the Sammy Miller kit as the bearings are thicker than 12mm.

Problem with a minimum age limit Mike - I know two young lads who have only ever ridden Pre65, they've never had a modern bike. Their fathers ride Pre65 and when they took up the sport they did too in order to ride with dad. One rides regularly and has done for a few years. It would be tough to say to him you can't have a ride you're too young when he's ridden in more Pre65 events than the total of some of the other entrants put together.

The early bikes used gaskets on the seal holders, up to around 1973/4, from then on they had O rings, no gaskets. The gasket set usually has the gaskets and O rings to cover either as I doubt there was a definitive change over date/model from gasket to O ring, but it's easy enough to tell, the seal holder will have the groove machined for the O ring or it won't. Can't understand the overfuelling theory to be honest, it would still run, just rich. However, if your bike ran ok before you put it away the needle and jet aren't going to have worn when not in use, so it's difficult to see how that could be the cause. I'd be thinking along the lines that whilst laid up some stale petrol has solidified somewhere in the pilot circuit and is preventing it from starting and running once the initial carb flooding with the tickler has subsided. A blocked or partially blocked pilot circuit can virtually stop a bike from running altogether (don't ask me how, this is just from personal experience) May be worth getting the carb cleaned anyway in a good sonic cleaner for peace of mind which should break up and remove any blockage. For what it's worth I had a clapped out carb on a model 92 I rebuilt last year and I fitted an OKO as it was a lot cheaper than an Amal (just needed the inlet manifold of a later 250 as the OKO is push on not bolt on) With just a slight pilot and main jet change it ran very well. Can't remember the actual jets unfortunately but it ran quite well straight from the box.

From memory... At least loosen the allen bolt at the bottom of leg beform starting to dismantle as the spring tension should enable you to undo it without holding tools, especially if you have an air/electric ratchet. REMEMBER, the damping adjuster is inside the head of the allen bolt so screw it right in before inserting the allen key, otherwise you may damage the adjuster, it's only brass (bitter experience) Undo the fork caps from the stanchions. The fork caps are screwed onto the internal damper rod and secured with a locknut underneath them. To remove the cap from the damper rod you need to hold the locknut with a spanner and undo the cap. Bit fiddly as the spring/preload spacer is in the way. You can then remove the spring and spacer etc. making a note of their fitted order. Turn fork upside down and pump out oil, also pump the damper rod as this holds oil too. Then remove the allen bolt from the bottom of the fork leg, hold the fork leg in one hand (or vice) and pull the stanchion sharply out. You probably need 2 or 3 goes to shock it free of the bushes. Watch that the damper rod doesn't disappear as it is now free, no longer held in place by the allen bolt. May be better to remove it before trying to shock the stanchion free. Once the stanchion is out you can replace the seals and bushes, just note their order before sliding them off. Reassembly is the reverse. To fill with oil you need the leg upright with stanchion fully extended but no spring. Fill to the top with oil, then pump the damper rod 7 or 8 times through its full stroke to distribute the oil internally. Refill to the top and then pump the stanchion itself 7 or 8 times but not quite right through its full stroke to completely distribute all the oil. The oil level will fall again. You are looking for an air gap of 95mm (Birkett's recommendation to me) Add or remove oil as needed. Refit spring/spacer and cap and screw cap back into stanchion. Think that's it, been a long time so I may have overlooked something but I don't think so. Reset your damping adjuster back to original position.

Yes indeed, the Pre65 title was purely to prevent the Bultaco and then the Ossa and Montesa that followed, from competing in classic events. A far better definition is British Bikes Pre70 which has long been adopted by some clubs and national series.

That seems fairly conclusive then, they were available before 1965, which contradicts everything I have been told about when they were manufactured.

Thanks Tony, mine did have some sort of case saver but I think it was more from rock damage than the kickstart. I can't remember exactly what it looks like, from memory it was different from yours, maybe the same as the one on the ignition side, but I can't find it at the moment, it's 'safe' in a box somewhere with some other parts. Maybe it will do the job. I'll have a hunt for it tomorrow

No, it's intact but that seems to be the return stop, not s stop to prevent the full rotation of the kickstart?

Does anyone know whether the Rotax motor has a 'stop' on the kickstart mechanism? Mine is the Jumbo but I believe it's the same as the 240/280 motors. Problem has occured in that the kickstart travel/rotation is long and on full swing the knuckle of the kickestart has gone round and punched a hole in the casing. I can't see how to stop this happening. It's never happened before but it's happening now. I've looked at the parts diagram and had the kickstart ratchet and spring out but can't see that there is anything to stop the kickstart shaft continuing to rotate until the kickstart hits the casing. There is no way I can kick it gently enough to shorten the swing to prevent this happening, not even using the decompressor, the kickstart travels full swing. I repaired the casing yesterday and it's holed it again today. Am I missing something?

They were defintely manufactured after 1965 so they aren't genuine Pre65 class eligible, definitely not Scotland. However, most clubs now run as Pre70 so it doesn't cause a problem. If a club is running a Pre65 class, a 2011 spec James/FB/Cub is ok, a genuine 1966 Sprite isn't. Oh the irony of Pre65 eh.....

If you're not using it on the road you have nothing to worry about with a plastic or fibreglass tank. The law that was passed around 1973 prohibiting the use of fibreglass (not plastic) tanks on the road was UK law, not an ACU ruling banning them from trials use. Presumably this law is still in force but there are plenty of bikes in use in road trials using fibreglass tanks.

I'm going from a none too clever memory here, but if the '74 swingarm is from a TY250A then I think they were frame mounted, not on the swingarm which would be why the mount is not there. Can't help you with the chain lube mechanism as I've never used one, I always blocked them off and manually lubed the chain.

I was working on my 340 last night so whilst the tank was off I took a couple of pictures of the alloy head steady. I can't post photos on here so if someone who can will PM me their email address I'll email them to you and you can post them.

Just another topic being subjected to the usual forum-itis. Lots of people 'in the know' who know the reason why the bike isn't really going to Sheffield. I've no idea what the reason is but in this day and age when professional sport has been controlled and ultimately ruined by big money sponsorship, it's the sponsors who rule and call the shots. To me, however ludicrous it sounds, it's perfectly feasible that the clothing issue could be the cause. Look at formula 1, the drivers aren't allowed in front of a camera without someone from PR shoving the appropriately logo'd baseball cap on their head. Lewis Hamilton has to mention Vodafone in every sentence To come up with a reason like this if they were covering something else up, Ossa would presumably need the agrement of the sponsor, I doubt they could just make it up. Would you take the blame if you were the main sponsor and not the cause of the problem.

Ossas and some Bultacos had stainless steel spokes as standard fitment, so they must be strong enough for competition use. I had my Ossa MAR wheels rebuilt nearly 20 years ago with new stainless steel spokes and that bike has been seriously used over the years and taken a good hammering. I've never even had to adjust a spoke in that bike, certainly never broken one.

Yes, they are a standard fitment to Betor forks fitted to Bultacos and Ossas They aren't thick enough to have any affect on spring tension. I can only guess that they prevent the oil squirting geyser-like, straight up the forks tube, from the top of the damper rod when the forks are compressed. For what purpose I don't know, maybe to help slow the oil flow and help compression damping? So yes, they do belong in there, but in my experience, there is no difference to the damping or fork action on either a Bultaco or Ossa if they are fitted or not.

They've already won two trials in the UK. If production bikes are seen to be winning or thereabouts in club and centre trials, then it is proving itself in the real environment of outdoor trials in the hands of club and centre standard riders. This has to be more relevant to potential buyers than what happens at the X-circus on a factory indoor special

Yes, I'd say the same, stick with the Dellorto. An OKO is a decent option if the original carb is no longer available, or was not particularly good, but a Dellorto is a good carb and available new. An OKO is minimum

It's the same flag, whether called the Union or Union Jack. The 'Jack' reference is because it was the part of the ship it was originally flown from (I've no idea what that part was) As far as I know, Union was added to the name some time later. I hope those lads never turn out in a Pre65 competition on those bikes - they look a bit handy...

SAE refers to the grade / thickness of the oil so SAE5 is thinner than SAE30. The thinner the oil the faster the damping piston will move through it, like trying to move your hand through a bath full of water as opposed to treacle. The forks will compress and rebound quicker with SAE5 than with a higher SAE. The SAE has no direct bearing on the quantity of oil used, or not that you need to worry about. The recommended quantity for the Bultaco is 160cc. They have a shorter fork leg than most other bikes. However, it's only a recommendation and there is tolerance to use more than that. Use your SAE10, start with 160cc, take it from there and add 10cc at a time if required, but 200cc is the absolute maximum

106cc is not enough, did you mean 160? The Bultaco forks take a bit less than other bikes with Betor forks so between 160 and 180cc is a benchmark for starting with. SAE depends on personal preference. Bulto forks aren't exactly the best in the world and even with 180cc (and more...) of SAE30 they can still top out. As you've got SAE10 already, use that and try 160cc to start with and add 10cc at a time if you think they need it. Once you get towards 200cc though they will start locking through too much oil

Is that with the rider..... Weight is around 95kg