woody

Yes, that's how I did mine - glad the info was of assistance.

That picture was taken at Robregordo this year, that's Chris Denney in the picture and I'm buried down by the Ossa back wheel looking at the swingarm which was from a 242 Montesa. I had a ride on the Ossa and it was a very capable bike, everything worked perfectly and felt very light to ride. Suspension set up was superb. The Bultaco was a bit overdone to be honest and other riders weren't happy with the Sherco forks and yokes - a step too far. All of the Puma bikes have original forks with reworked internals so they look correct. The front end on that bike looked out of place and is wrong in my opinion but in practise at least, I'm not sure it actually offers any advantage over a Puma fork set up which is excellent. I can't remember if it had a Puma engine or not but it did go well.

It wasn't Wrighty we were referring to Charlie, just one of our local riders. No animosity intended towards the person involved, just a bit of local banter.

But that isn't representative of the classic scene overall. Most classic club trials are on the gentle side and have 2 sometimes 3 routes, so there are plenty of events that would accomodate a bigger bike. Things only start to get difficult in the ACU Traditional series and very occasionally, the Miller series on the hard route, but there is always the easy route - and they are National Championsip events after all. The Manx Classic is a tougher event and a standardish big bike on the hard route would be a handful for a skilled rider but there is an easier route to opt for. Pre65 Scottish is fine for a big bike as proven by the number of rigids that take part. As far as which bike - impossible to answer really as if you don't have a favourite marque, or something you have a particular affinity for then the choice is huge. Most people gravitate to the type of bike they used when they first started riding, British from the 50s or 60s or Spanish or Jap from the 70s. If you don't fall into this niche then you have to really look at the combination of your ability, the type of events you will want to use it in and what is catered for in your area. Just because it is a 'classic' (hate that term) it doesn't mean you have to ride it in classic events, most modern trials have 3 routes these days so you can ride a twinshock or Pre65 on the middle or easy route. Choice all depends on what you want to ride and why really

Don't overlook the fact that to use a DT360 piston, you have to open out the cranklcase mouth to take the bigger sleeve, fit a spacer under the barrel to get the correct port timing as the DT piston is of different dimensions (pin to crown height) and machine the head out to match the new bore size (I have no idea what needs to be done to the head but they are definitley altered on a 320 Majesty, you can't use a standard 250 head) You also need to open out a 250 head gasket to fit as there is no 'off the shelf' head gasket for a 320 - assuming the DT gasket has a different stud pattern.

Cota 247 does have a vertical slot in the back of the piston and the earlier Cotas are 247cc using a 72.50 piston. Later models may have been sleeved down as were Bultacos and Ossa Grippers, but not the earlier models. Bultacos don't have a slot in the back of the piston, they have a couple of small holes at the top, but no slot.

In addition to the above, Beta twinshocks, TR32,TR33, Fantic early monos 301 etc, Armstrong, Aprilia all used Grimeca hubs. There may be slight differences between the various bikes and models in design, particularly with the brake plate, but I'd think most could be made to fit without much effort. They should all have the same spindle diameter. Watch out for the early SWM and maybe Gori hubs though, as they had a cush drive. Probably still fit but very heavy in comparison.

Hi Javier, no disappointment for me in not getting an entry as I didn't really expect to - 2 acceptances out of about 11 attempts, this one being the last I'll make. I can take it or leave it these days, there are plenty of other trials to ride in. Hope to see you in Robregordo again next year. Yes Simon, I can make a good guess.

You need to bear in mind as well that the modified Yam frame version of the Majesty (ie; the original Majesties) had a fair reworking of the entire rear subframe and engine cradle, not just a case of repositioning the top shock mounts. Whilst that alone will probably improve the TY suspension, it isn't going to put it on a par with a Majesty. The front frame downtubes were shortened by almost 2" and the rear of the frame altered to match. How they did this I don't know, I've had a Majesty Yam frame and standard TY frame side by side and although I can see the difference, I can't see how it was done. Very clever though as the rear suspension on the Majesty, with decent shocks of course, is close to the best twinshock rear suspension setup I've ever tried.

Yes, list of competitors must have been finalised as I've had my annual bugger off you're not riding letter

No, they are the early Fantics, not the same. The Jumbo is the same as a 303 Fantic though, odd size of 20x43x14 (maybe 15)

Anyone know the bearing number? I've put the old one down somewhere and can't find it at the moment to get the number. I have to go to the local bearing stockist tomorrow so if they have some in stock I can get some whilst I'm there.

Thanks Wayne

Any of you Montesa experts out there able to confirm the oil quantity for the gearbox on a 1973 247 Cota? I have a spec sheet which says 200cc but that can't be right, surely? It states 300cc for the clutch which sounds ok as that's the same as a Sherpa but a Sherpa has 600cc in the gearbox, so 200cc for the Mont seems low. I have a Clymer manual and that says 200cc for the clutch and 300cc for the gearbox..... Just spent the last 2 days cutting open, repacking and welding up the middle and end silencers and what a **** job that is, so now I want to see if the pain was all worth it, get it fired up and see if the newly rebult motor purrs, just like my mate's did back in '75 - don't think I've seen one running since then...

New class for 2010 then - British Replicas Looking forward to seeing who has entered what in which class at the first round..... I guess riders could say they should still be in the 2-stroke, pre-unit or unit class or whatever, as there are no 'replicas' of 60s bikes out there.... Now, where's the avatar for slapped wrists and mischief making

Don't know of any limited production run models in 2001 with the Bultaco name. The Bultaco name was only used in 1999. The original Sherco, or GasGas clone.... was produced in 1999 and they hired, leased, borrowed or whatever, the Bultaco name to launch the model. They couldn't call it a Sherpa because, somewhat strangely, Kawasaki owned the rights to Sherpa. Bizarre when Bultaco had produced a Sherpa model for nigh on 20 years from the early 60s. So they called it a Bultaco Sherco. In 2000, the Bultaco name was dropped and it became plain Sherco. Picture here: http://www.ataq.qc.ca/galerie/showimg.php?...rco1999_2.5.jpg

ok, thanks for that - I see where I may be going wrong as I was trying to fit it with the straight part of the spring already located in the slot. I'll try again tomorrow. After that, there may be a further post about fitting the chain tensioner spring...... something else I've had to walk away from today....

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.