woody

Anyone know how to tension this f***ing thing..!!?? I've looked at this for what seems like hours and can't figure it out. Clymer manual is a great help - refit kickstart...!! Parts book is just that, shows the parts, no instructions. It came off the bike working so I know it will go back on - somehow... There is a notch in the kickstart where the hook of the spring locates presumably. Can't see anywhere else it goes. With the shaft fully home, the spring fitted to the shaft and the kickstart offered up in the 'home' position, the hook lines up almost directly with the notch in the kickstart. However, there is no tension on the spring like this and when the kickstart is rotated it won't return. How is the spring tensioned? I just can't work it out. Anyone know.

Yes. The tube type tyre will not fit properly on a tubeless rim. The tyre is creeping around on the rim which is why the valve is pulling out. The tubeless rims use a thick rubber band around the inside of the rim to stop air leaking through the spoke holes. Hopefully this is still fitted. If not you will need to get another and you will also need a new tubeless type valve. This is different from a normal tubeless valve as fitted to cars or road bikes so you will need to get it from a trials dealer. Then the fun starts of trying to fit a tubeless trials tyre. If you've never done one before, presumably not, it will be best to find someone who can show/help you do it, or take it to the nearest trials dealer and ask them to fit it/show you. It can be a real bitch to get the tyre to seal on the rim, you need a compressor that will inflate to around 100psi and it works best to have a line off the compressor straight onto the valve (valve removed) without a gauge. You need an immediate high pressure blast of air into the tyre to try and pop it straight onto the rim, so the fewer obstructions between the compressor and valve the better. Once the tyre is seated on the rim you can let it down flat, it won't come off the rim now, then refit the valve, refit the gauge to the airline and inflate to the correct pressure. Maximum, this would be 5psi, as mentioned in the previous post they run at 2 - 5psi depending on tyre and conditions. IRC or Dunlop are the easiest to fit as they come with the beads spread apart so pop onto the rim easier. On Michelins the beads are closed together like a clam, so they are more difficult. Your local bike tyre sales may do it for you but normally they hate the sight of tubeless trials tyres. As regards which tyre to buy, the IRC, Michelin and Dunlop are all roughly the same price and all work equally as well in most conditions until you become good enough to feel the difference, but IRC is very very good in muddy conditions. The IRC has softer sidewalls than the other two so if you weigh over about 13 stones you really want a slightly higher pressure than on the Michelin or Dunlop as the IRC can roll on the sidewalls when traversing cambers or going over rocks. In cold weather as we have at the moment (UK) they will stand a lower pressure as the rubber is harder but when it is warmer the sidewalls soften considerably and they roll with 3 - 4psi in them so 5 may be needed. The Michelin and Dunlops don't suffer from this. Don't consider cheaper tyres such as Mitas, Barum etc as it is a false economy, they don't perform anywhere near as well as the 'big three'. As you're new to trials, if you don't want the expense of a new tyre just yet, if you know anyone that already rides, see if you can get a good used tyre from them to start with.

Can't comment about the strength of your swingarm now that it has been modified as I wouldn't know, but as regards the rear wheel, the one out of the 71 Alpina will be different from the one I used so what I did to get chain and rim alignment may not necessarily work with your wheel. It shouldn't be too different but you'll need to check. The Bultaco frames up to mid '72 were quite heavy as they only began using lighter materials from that point.

I've just had a Bultaco rear wheel rebuilt to fit in my C15. I have the standard swingarm fitted, can't see that it has ever been widened as it looks the same dimensionally as a spare I have. Yes, it's tight on clearance but it's never caused me a problem. If you fit a chainguard it won't clog the final drive with mud. Can't comment on lengthening the swingarm as mine isn't. Depends on other frame mods really as to what affect that would have. The wheel is the type fitted to the '75 onwards Sherpa (model 159) All I did was machine back the boss (or whatever you call it) from the brake plate where it sits against the swingarm as the sprocket has to sit very close to the swingarm for chain alignment. Leaving the boss as standard pushed the sprocket too far away. I think the Bultaco spindle fits straight into the C15 swingarm spindle slots and I don't think I had to alter the standard wheel offset to centre the wheel in the C15 arm.

I made the sleeve out of aluminium (no idea what grade etc) The fit is such that it can't be pushed in by hand, it has to be tapped in with a soft mallet, same as you would a bearing.

You carb will be an Amal MK1 if it has the tickler, the MK1.5 was a MK1 body but with different pilot circuit and with a choke lever fitted, no tickler. If it is a 627 then the chances are it is the original carb so you could also have wear in the throttle slide/throttle body which may hinder starting from cold as it will weaken the mixture a bit. When you press the tickler down until fuel pours out, this has flooded the carb and the biike should start first or second kick if the carburation is ok, even with a worn slide generally. (this is assuming the electronic ignition is performing correctly and the timing is correct)

I'm not an engineer so I don't begin to understand the various fitting methods you mention in point 1. The sleeves are 3mm wall thickness which isn't thin to me, the previous sleeves I had were to take TYZ head bearings and they were only 1mm thick. All I did to fit the sleeve was to tap it in using a drift, same as I fit the taper roller outer cage. Once the sleeve was in I fitted the outer cage into the sleeve by the same method. Simple as that really. To remove the stem from a Bultaco fork yoke you need to press it out, no other way that I know of.

http://www.rexcauntracing.com/ He never actually lists the Ossa springs in his products category for some reason, normally you can find them in his ebay shop but they aren't listed there either at the moment. He definitely sells them, may be out of stock at the moment. Contact details are on the website if you want to ask him

Yours is correct, the other one has been modified by cutting off the bottom frame tubes and fitting the bashplate. It's done to gain a little more ground clearance

Found the wheels To measure, I put a long ruler across the hub with the brakeplate removed so it overhung the edge of the rim and then measured the distance to the rim (the flat side of the rim rather than the little lip that runs around the edge as not all rims have that lip) Front offset is 22mm Rear offset is 68mm

A rear MT43 is an acceptable tyre in terms of providing an adequate level of grip but it's old technology so it is not as good as a modern Michelin/Dunlop/IRC in any conditions other than snow or ice where its harder compound bites in better. Same for the front really - they'll grip ok, but a Michelin is probably the best all rounder on the front. In the end, depends how serious you are as to how much you want to spend. The pirelis will be adequate, no more.

I should be able to help with the wheel offsets but not until the weekend, I have a pair of 240 wheels but at the back of an unlit shed underneath loads of other stuff - unless someone else provides them beforehand Why not just fit a new standard spec Delorto - not sure what the prices are in Australia but here they are a bit less than a new VM Mikuni at about

too right - he'd reverse the charges

I don't mean to jump down anyone's throat here, each to their own and all that, but why is there a need to find a trial that has a class for a type of bike. Surely, you ride the type/make of bike you enjoy riding and just go to a trial and ride it. Most clubs have at least 2 routes now, many have 3 or 4. Just ride it on the route that suits you and that bike. If there is no aircooled mono class just enter whatever is appropriate for you - clubman, novice o/40, whatever. It's what I used to do on my Ossa long before the various pre65/twinshock series sprung up. What's it matter if there is no specific class. Never can understand this. Only time it matters is if an event is for a specific type(s) of machine or if it is a championship for specific type(s) of machine. Then obviously you have to comply. Normal club trials cater for just about anything these days. Some classic clubs tend to try and keep more modern bikes out. Don't know how old you are but couldn't you ride one of the over whatever on modern bike classes at Bath

Assuming you're using the Jap kill button with two wires, one goes to the larger spade terminal on the HT coil (should be the blue wire from the stator if it's original wiring) the other to earth.

You don't mention ignition timing - have you checked that

Michelin x11.... It's easy enough to rip the knobbles off those on a trials bike, never mind a KTM - brave lad.... Anyway, the tubeless rims like that on your Gasser, are about

Which tubeless tyre are you thinking of running on a KTM - enduro/motocross tyres are tubed and the tubeless ones they were experimenting with are completely different from trials type. It's usually only the Pirelli MT43 that riders use on enduro bikes and that is tubed. It's a hard enough compund/construction to put up with the abuse an enduro motor will give it. The tubeless trials tyres are modern soft construction and I would think they'd be shredded in minutes on an enduro bike. A rim lock isn't required on tubeless rims and once you've drilled the rim to fit one you're going to have to fit a tube as it will no longer seal....

If you want to be fussy, the 85 Alpina frame doesn't have bolt on footrest hangers like the 80 With the 49, depends which 49 frame you're referring to, there are 3 types and only the last type is the same as the 80 (excepting tank, seat and sidepanel mountings as mentioned) First type the shocks are more upright and there is only a single tube under the engine Second type has the shocks repositioned but still only single tube under engine Third type has two bottom frame tubes with wire mesh between, like the 80.

Magical has one leg longer then the other...

Montesa Cota 247 and Ossa MAR both use a spindle attached to a right side pedal which runs behind the engine through bushes in the frame plates by the footrests which then operates a rod or cable on the left side. The Montesa set up is better as it uses an arm attached to the left side of the spindle which is then connected to the brake arm on the wheel by a rod or cable. The Ossa's is a slightly more tortuous affair where the outer cable is used as the actuator rather than the inner cable - definitely not worth copying. I think Sprites have a spindle arrangement too.

With that sort of form there's every chance he could go past 7 wins - hard to see anyone who can match that ability - stop or no-stop rules

Yes, whilst dished sprockets were still around Keith Horsman made a very neat bearing carrier that bolted onto the dished sprocket which gave support to the spindle. You ended up with 4 bearings on the sprocket side of the wheel. The spacer used with the flat sprocket conversion also acts as a bearing carrier.

The bikes had a nice dished sprocket as standard. An alternative aftermarket conversion was to fit a spacer to extend the hub and a flat sprocket. This was generally a Sammy Miller conversion, not sure if anyone else did it (in the UK) With the dished sprocket, there was a long spacer between the sprocket and swingarm and as the spindles are only 12mm and a bit soft, the pull of the chain could bend the spindle slightly where it was unsupported. I don't know whether the flat sprocket conversion was to cure this or because it was cheaper to produce than a dished sprocket - or both, although pattern dished sprockets were produced as well by some companies. Dished sprockets have been unavailable for years now, but finally they are being reproduced in Spain

Found it thanks - reason I completely missed it is because the clutch arm is located incorrectly and at the wrong angle. It's pointing forwards so the end where the nipple fits is way in front of the locating lug in the bottom mount. Easy enough to put right at least. Thanks for your help.