woody

Some clever people in this world.... Who also know how to make a few quid... The unparalleled global viability of these new fuels lies not only in the exceptionally simple and relatively inexpensive process which creates them, but also in the fact that the ‘feedstock’ used to produce them is entirely renewable. Yet the cost will still be equal to the cost of a barrel of unleaded. Just when you think a cheap fuel alternative is on the way...

Virtually everywhere is now Pre70, not Pre65, so 4 speed not an issue. Definitely not in the Manx, Yorks Classic have their own rules on their website. Scotland is about the only trial that still runs to Pre65. 4 speed engines aren't a problem and are accepted in Scotland - up to now anyway. Just another vagary of the rules - probably because the first 4 speed engines look identical to the last 3 speed so unless you're checking engine numbers you can't tell.

The thing to remember is that these are trials bikes, not Motogp bikes and having the timing absolutely to the degree isn't really necessary. They'll run with the timing anywhere between 1mm to 4mm before TDC. Towards 1mm the engine pick up is slower, towards 4mm it's quicker, you just put it at the setting that gives the response you're happy with through experimenting. 4mm is a bit extreme I know, but I've run Ossa MARs at 3.5 in an attempt to liven them up. Works setting supposedly but it didn't make much difference. On my TYZ Yam and SWM Jumbo I used to run both with the timing fully retarded on the backplate which made the TYZ throttle response smoother and the Jumbo, which is an animal, less aggressive - neither is anywhere near the manufacturer's recommended setting. No problems with performance, both still pulled as they should and both would rev out cleanly. You'd need a ship's anchor to hold the Jumbo back anyway... I'd wager that if anyone rode my 340 Sherpa they couldn't tell me what the timing is set at from the way it peforms. If you want to set it to recommended setting, then surely the best way is a dial guage and multimeter with beeper, as mentioned before

I have read more about this phenomenon having never heard of it before. Perfectly normal if you've kicked hell out of a bike and it isn't firing. That puddle of fuel in the crank is only there because you have been continually drawing fuel in when trying to start it, some gets pushed out the exhaust, some stays in the engine. When the bike is running, that puddle of fuel will get burnt off, it doesn't stay there permanently, so isn't the immediate cause of the bike not restating after you have stopped it. This is where a decompressor is handy, if you kick the engine over repeatedly using the decompressor, it will help get rid of the fuel and help get it started. The only other way fuel can get into the crank is if the petrol is left on and the carb floods. Fuel will then overflow into the inlet and down into the cylinder. This will involve a lot more fuel in the engine than you describe. Why are you so reluctant to eliminate the kill button from the list of possible causes? Electrical problems defy all logic and sometimes you just have to employ trial and error. Disconnect it - at least it will prove whether it is at fault or not. I would also earth the coil direct to the frame and get rid of the wire to the engine - it's not how they are meant to be earthed, no bike left the factory like that. The point I was making earlier about a weak spark is that although the spark looks strong, that may not necessarily be the case and when under compression, the pressure inside the cylinder is enough to snuff out the spark. It has nothing to do with the kill switch knowing the plug is in the cylinder - it's simply that the spark isn't strong enough under compression to fire the mixture - despite it looking fine when you test it As I said, it's trial and error and you need to eliminate all possible electrical causes - including a nick in the wire from stator to HT coil, especially where it leaves the stator as they can always get pinched here when fitting the stator - just because it has been renewed at some time doesn't mean it's not at fault. Also, as someone else mentioned, cut a piece off the HT lead and refit the plug cap - even if the end of the HT lead looks in good order, just do it. The way you say your bike performs when it is running doesn't suggest anything wrong with carburation. Concentrate on the electrics until you have eliminated all that has been suggested.

Raising or lowering the needle in the slide will have no affect, it only controls the fuel / air mixture passing from carb to engine when the engine is running. If the bike isn't firing when you are trying to start it, the plug will be wet. It doesn't mean a flooded carburettor. If the carb was flooding the engine wouldn't run smoothly. You would also have fuel running out of the carb. A strong spark visually doesn't mean it can't be extinguished under compression if there is an electrical problem. You haven't yet eliminated the kill button, at least disconnect it and see if the symptoms persist, if you don't want to replace it. Are you sure there are no breaks in the wire from stator to coil Also earth the HT coil directly to the frame by rubbing the powder coating off the coil mounting bracket completely until you see shiny metal on the entire mounting face of the bracket. Earthing it to the engine may not be a good idea as the engine mounts are also powder coated and if these haven't been cleaned off thoroughly you will have a bad earth. Until you are certain of these things, you haven't yet eliminated the electrics entirely as a source of the problem

The way I read the exhaust rule is that you can have an aftermarket part like a WES etc. But you can't fit an original manufacture exhaust from a late model to an earlier model - so you couldn't fit a clubfoot rear silencer from a Sherpa M159 to a Sherpa M80 or M91/92 ? Same with airboxes. If you fit a 199b airbox to the earlier 199 or 199a models the bike is automatically moved up a class. Sometimes, things like this are done for practical reasons, not performance, as the B airbox is a more practical design and makes the filter easier to service. I've had a new airbox made for my Armstrong for the same reason. To remove the airfilter or airbox from an Armstrong Hiro is really awkward and time consuming. The one I've had made lifts straight out of the top of the frame, no need to remove the rear wheel and one shock absorber. No performance gain but this modification would put it into the Open class. Javier - what do the riders think about these new rules - from what I have seen of the bikes in Spain, most have been modified in some way or another which would put them in the Open class. I always thought the modifications to the bikes in Spain were sensible as generally the bikes still looked like the originals apart from all the bright paint, chrome and polish. The number of bikes using more modern components seemed very few - apart from the mudguard brackets and tubeless wheels. I don't undertand why there is a problem with tubeless rims / tyres = in any organisation.

Generally, they don't use them in Spain, there are one or two but in the main they use the originals - what the regs now prevent is using the late 90s Gas Gas style mudguard clamps and bridges, as seen on the Puma bikes. There are so many bikes fitted with these you have to wonder how many bikes will be in anything other than the Open class.

No, just the bushes

If you search the twinshock or Montesa forums you'll find info on removing these - they are tapered and can be stubborn. Look out for O rings on the bolts (either side) that hold the crankcases together as this was Montesa's excellent way of making the gearbox and crankcase oil / air tight. Make a note of which bolts have them for reassembly. There are shims either side of the crankshaft underneath the crank seal carriers When you split the cases try and leave the gearbox sitting in the R/H side casing (ie: final drive side) There are shims on either end of some shafts and you won't want them rolling around on the bench with gear cogs etc. Also, some cogs slide on needle rollers, not cages but 3 loose rollers, so watch they don't fall out as well as they are different lengths for different cogs.

170lbs for a KT.... I doubt the works bikes were that light, have you checked your scales... The 2012 spec lightweight Cubs and James would struggle to achieve that A stock KT is about 215lbs and most of that is the frame which is way too heavy and over-engineered. The motor is actually quite light, especially compared to the TY250 motor which is a huge lump. Even Sammy Miller's Bultacos with the lightweight frames and all his other weight saving tricks were still around 190lbs. As regards the original question, Trials is physical and if you get fatigued doing light physical activity, you are definitely going to get fatigued just riding a bike over rough ground, regardless of the bike. Riding a smaller lighter bike will minimise that, hence your question no doubt, so a TY175 or Fantic 200 would be my choice as both are comparitively light and won't have too much power that they pull you around, which will also tire you out. Both will have more than adequate power for what you need. If you can afford it, a modernised Bantam is about as light as you can get If you choose modern, avoid 250 or bigger as they will pull you around. A 200 Beta is an excellent bike, as is a 4-stroke 125/175/200 Scorpa Another considersation is not just the riding of the bike, it's manhandling it when things go wrong, holding onto it and picking it up again, all of which will tire you quickly if you are already tired from riding. All of the above are easy to start, although a bike that starts in gear is always less hassle. If budget stretches, I know someone who has done a couple of electric start TLR200 Hondas using the ching-chang engines (or whatever they're called) It doesn't get any easier than that...

The fact that it is happening consistently with you operating the kill switch could indicate a possible problem with it - they can and do give problems, particularly cheap versions. I'd replace it as a matter of course. A spark you can see at the plug can get extinguished under cylinder pressure at the speed a kickstart turns the engine if there is a bad connection somewhere. Once a bike is running there is enough power generated to overcome bad connections, so you don't have a problem until you stop it again, or revs drop to almost stall speed. Genuine Yamaha are very good and around £15 http://www.ebay.co.uk/itm/Yamaha-TZ250-89-99-Kill-Switch-Gen-Yam-New-/400369891579?pt=UK_Motorcycle_Parts&hash=item5d37e7b8fb or there are patterns a bit cheaper but for the sake of a few quid I'd get genuine. Timing won't be the cause of the problem and if the bike runs fine when going the timing is likely to be correct anyway. The bike will still start with the timing advanced or retarded. I ran my SWM with the timing on full retard. If the timing was out markedly performance would suffer and it would either pink/knock when hot or suffer from lack of power and have a slow pick up. I'd begin by looking to the kill button and then check that you don't have any nicks in wire insulation from stator to cool. I think you're worrying too much about this 2-stroke 4-stroke thing Nothing to do with starting problems but I'd run it on Shell V-power or equivalent anyway rather than the lower octane stuff. These bikes used to run on 4 star when new. To adjust the timing you just remove the flywheel and rotate the backplate in the direction of the flywheel rotation in order that the points open nearer TDC. But I really wouldn't bother with this as it is not going to solve your problem. Consider fitting a decompressor kit too as these can be used to aid starting. Hold the lever in and give the engine 3 or 4 good kicks on full throttle - this puts a charge into the engine without flooding it, then let the lever out and give one good kick which should see it fire u. With practise you can actually use the decompressor on the 'start kick' also as it removes the resistance from compression when first trying to kick it.

What carburettor is it as you mention a choke lever and the original Amal fitted to the Cota doesn't have one, they have a 'tickler' to flood the carb to help cold starting. If it is fitted with a Mikuni which is a popular conversion, they are buggers for flooding and yes it will affect starting if too much fuel is leaking from the carb down the intake when warm (despite the overflow that lets fuel escape) If it is a Mikuni and it doesn't have one fitted already, swap the float needle for one with a rubber tip to get a better seal when the float height should shut the supply of fuel off. You can get them from Allens. PS - I really wouldn't hold a naked flame over the plug hole to burn off fuel. Bikes have been set on fire simply by the spark from the plug when checking for a spark. Holding a naked flame over the plug hole with all that vapour is a huge risk - add to that possible leakage from the alloy tank due to age and stress related related cracks.... Your flirtation with 2-strokes could be a brief one if you hold to that practise...

It's to cushion the rebound of the forks when they fully extend or 'top out' on rebound. If you pull your forks up hard without any oil in (or even with oil in, in the case of Bultacos...) the clunk you hear is the metal sleeve that's locked in place with a circlip in the botton of the chrome stanchion, comping into contact with the top of the damper rod. This is the impact that the spring softens. The plates they sit on, damping valve and seat, are what help control the oil flow to provide damping. No idea if you can get these parts new anymore, try Bultaco UK as mentioned above or: John Collins at JC Motorcycles Port Talbot Sammy Miller Alternatively, it may be worth looking out for a pair of scrap rusty forks on ebay for the innards, or for used parts, try: Ellastone Offroad breakers Wakefield Offroad have broken lots of trials bikes. You could also use damper rod parts from an Ossa as they are the same forks, the Ossa just has slightly different damping characteristics (better) You can use the damper rod assembly complete off an early Ossa with the shorter forks as they are the same length. Later Ossa forks ('76 on) are longer, so the rods may be longer too, can't remember. The individual parts, the springs, valve and seat, would be fine though.

Fuel isn't a problem as he uses ethanol resistant resin. I've had the 'prototype' tank on my 340 for 12 months now with no problem and I never drain it, it always has fuel in it. I've never actually had a problem with fuel in any of the bikes, both the M49 I used to have and the M92 I've been riding this year used the original Bultaco tanks and neither suffered fuel related problems. The M92 has had fuel in it constantly since I got the bike at the start of the year, I've never drained it. Even the two holes I 'repaired' with araldite have held up. I only use Shell V-power unless I'm away somewhere and can't get it. Edit:- forgot to mention the TY mono cover. The reason for the cover, rather than an actual tank, is purely to tidy up the old weathered plastic tanks. As the tanks are structurally ok they don't need replacing, so the cover is just a way of giving them a new appearance and allows a custom finish as well.

John Collins of JC Motorcycles Port Talbot has a lot of used Bultaco parts so may be able to help. Wakefield offroad have broken loads of trials bikes over the years, so worth a try. Ellastone Offroad breakers Keep a look out on ebay as it's full of Bultaco parts. This part is the same for most Bultacos from the 70s and 80s, so look out for Pursangs, Alpinas etc as well as Sherpas. Even if you end up having to get one from ebay USA it won't cost that much to get it here.

You can buy a new one from Shedworks Bultaco UK and Millers also did them but not sure if they still do now.

All the 'slimline' bikes from M80 up to the 1975 M150/1 had the red fibreglass tank seat unit fitted by the factory. Somewhere around 1974 fibreglass tanks were outlawed in the UK, so the UK importers replaced the tanks with the alloy tank/seat unit, like the one on the front of the Haynes manual. These alloy tanks were blue. It's not unusual for this alloy tank to have been fitted to other models over the years. Your 92 would originally have been sold with the red fibreglass tank/seat.

Colin Leese and Alan Miles lost their bags at the recent Downland Trohy trial. Both bags had been left with the petrol cans in the carpark by an observer who had brought them back from the last but one group of sections, but someone else has picked them up. The bumbag is blue with three pockets and contains some useful tools, the camelbak has a burn on it from a bike exhaust. They'd like to get them back if possible, so if anyone has a blue bumbag and a camelbak they are wondering what to do with, please give Colin a call on 07815 977323

As mentioned above, the spark can look weak when checking, but the HT coils can give trouble on the aftermarket ignitions, so worth checking. They're cheap to replace if warranty has gone..

I'm not saying that is the plug to use, just that it is the plug I have in mine and the bike runs fine on it. I've used between BP5ES and BP7ES with no problems in all my Bults and Ossas. I doubt you'd tell any difference between them. I can't anyway, they're too close together in the heat range. The only plugs I don't use are the micro-tipped things which are no good for trials bikes, they're made for constantly high revving engines and need the revs to keep clean, such as motocross. As soon as you run the engine slowly like on a trials, or as we did, an enduro bike, they can whisker and pack up. No idea whether TTS is semi or fully synthetic, I've used it for years and never had problems, it doesn't gum up rings or exhaust and the piston is always nicely coated when I've removed a cylinder, as is big end. It's what I've run my 340 on in the two years since it was rebuilt and it still sounds like new and it has taken some real abuse in sections and done a lot of roadwork.

Nothing you mention will make it 'easier to start'. The Bultaco will start first time on points and Amal if in good order. I have electronic ignition and a Dellorto on my 340 and it is no different to kick up than my old model 92 which is on points. I think if you spend money on new ignition and new carb, you're going to be disappointed. I'm guessing you're having problems because of the high kickstart, kickstart gear ratio and the compression. Try and get the technique better. Get the kickstart positioned by pulling in the clutch, rotating it then letting it back up to where it is comfortable, just on or past the vertical, then usually one hard push will do it. Don't kick or thrash at it, as that usually just results in a kick-back and your knee in the bars. Not sure a decompressor will help on the Bultaco due to the ratio and short throw but if you can get one fitted relatively cheaply it's worth a try. If you do end up getting electronic and from the UK, i'd get one from Bultaco UK or Rex Caunt (same ignition I think) rather than Electrex. I use 50:1 with Castrol TTS and a two year old rebuilt motor still sounds as new and it has had a good hammering in that time with regular use. Won't make any difference to starting over 40:1 though. Plug is NGKBP6ES Nice Stingray

I remember seeing loads of those tank units when I called into Gateshead (or Sunderland) to get some spares, mid 90s I think. Not a shop though, a unit. There were a lot.... always wondered what happened to them all.

TLM50 bored out to about 70 - 80cc

That's how I remember it, the 323 was out first with the red frame, the 240 followed with the blue frame. I had a 323 from Robinsons in Rochdale, tested one at Back Cowm quarry and bought it. It was my first mono. Really wanted a TY Yam but couldn't afford one and Robinsons were pushing the JCM so got a deal on it. The 323 had a lovely motor and wasn't a bad bike actually, although memory a bit hazy now on the finer points. The shock went but they replaced it no problem but eventually it got traded for a new TY Mono when I could afford one. Not with Robinsons though, those barstewards wouldn't have it back and kept making up all sorts of excuses about not having any TY monos available. That was the last I ever dealt with them.

For some good advice on Bantam builds you could try Jim Pickering on 07850 836571 who builds the Drayton Bantams He has a good number of years experience developing the Bantam trials and has turned out some very nice bikes. The engine in the rigid Bantam that Juan Knight won the Manx Classic on was one of jim's and he has done work for a few other 'names' as well. He can supply parts, build engines or complete bikes. Definitely worth a call if you're looking to build a competitive Bantam.