dadof2

You probably should NOT press the crank into the bearing as this can put excess force on the races themselves. It is far better to pull the crank through the bearing by having a spacer that matches the inner race and making up a tool that grips the flywheel or drive side nut threads. This is difficult to describe in words but Yamaha do special tools for this and the procedure is described in their workshop manuals. Essentially the aim is to use methods that mean the bearing seating or crankcase joining processes never rely on putting forces through the ball berings. Cheers

There should be a black and white wire coming off the CDI unit with a bullet connector socket on it. A standard Yamaha stop switch has a matching black and white wire with a bullet plug on it to connect to wire from CDI. Most people put the stop button on the left hand handlebar where you won't accidentially lean on it. Cheers

An updated version of Bell's book was published in 1999 but as you say both these books tend to concentrate on harder running engines. Having said that I've witnessed some pretty hard run 125 trials bikes. The worst thing that can happen with too much oil is plug fouling but at 24:1 with correct jetting this in my experience does not happen. At 24:1 with good quality mineral oil (shell 2T or castrol TT) an air cooled trial engine will be virtually unworn after several (6 or 8) seasons use. At 40:1 with Putoline MX 5 (again a good quality oil) an air cooled trials engine will need reboring after about 2 seasons. My experience on MX engines suggests that going from 24:1 to 40:1 approximately doubles the rate of bore / piston wear on cast iron linered engines and increases the rate of piston wear on plated cylinder engines. Switching from semi synthetic at 40:1 to mineral oil at 24:1 noticeably reduces running temperatures on plated bore watercooled trials engines. Perhaps the most likely drawback of a lean ratio say 40:1 and over is its inability to resist water penetration if you are unlucky enough to get water droplts in your engine. Cheers

You don't say how you checked the output of the stator and trigger coil. Friend of mine had an 07 250 gasser and it did same as yours. It was trigger coil but he had to buy whole stator and flywheel as they come as matched items. To check outputs properly you need disconnect stator wires from CDI, remove spark plug and put in a few CCs of oil. Spin the rotor with a power drill at about 450 to 600 RPM and measure the output with an AC voltmeter or better still an oscilloscope (PICO ideal if a local garage has one). Expect about 23 to 30 volts from source coil and 1.5 to 4 volts from trigger coil. If you can get similar bike that is working do same procedure and compare the results. If voltages look OK you can still have a problem because static no load resistance measurement may not be accurate. You can have a poor internal connection on either coil that will prevent full required current flow. To check current flow you need PICO or similar diagnostics equipment. All the best.

Before you make up your mind what oil and ratio to run I suggest you read: Two stroke tuners handbook by Gordon Jennings - Do a search and you can read it on web - no need to buy Two stroke performance tuning by A Graham Bell - You will have to buy this, published by Haynes of car manual fame. Note that the oil suppliers often use terms like "up to 80:1" and "follow manufacturers recommendations". I would never go leaner than 32:1, sure with modern oils and engine materials you are unlikely to seize even at 80:1 but less oil means more wear. A good film of oil between piston and barrel is very important to conduct heat out of the piston to control piston crown temperatures. Cheers

Big John - you say the WTC machine is not designed for Scott or SSDT, perhaps someone should have told Doug? I don't know if Martin was at the Scott but I bet his face would have been picture if someone had told him his lad was on the wrong bike! Unfortunately some of this topic is speculation because we don't know whats in Dougs Beta, nor do we know exactly what went wrong. In view of the level of interest perhaps BETA UK could tell us exactly when they find out. The fact is Doug has run out of sparks on two significant occasions and this happens to other Beta riders all too frequently. I have an 07 125 Beta and it had new electrics before I bought it and I think every Beta I know (mainly 250s) has had to have at least new stator coils. Basically the electrics on a bike consist of, flywheel with magnets, lighting source coil or coils, ignition source coil or coils, ignition trigger coil, control unit and HT coil and wires between. With the exception of dumping the lighting components and their mountings there really is not any scope for significant lightening of components. If I had to guess I would suggest Dougs bike would have the lighting bits removed and a programmable "ignition only" control box fitted instead of the standard item. Cheers

I as a UK resident am totally against the word mototrial. There is the risk it will link trials with speed trials, motoGP and Motocross. This will make it easier for opponents of offroad motorcycling to group us with sports that are easy to portray as fast, noisy, land damaging and bad for the environment. Far better it is called "observed reliability trial" even if it is a mouthfull. Cheers

Are trials bikes becomming too light? Is all this developement really worthwhile. I watched at Whaw Bridge (Scott) on Saturday and most of the riders made no better job of it than we did on Bultacos back in the 1970s. Considering we now have stickier tyres, whats the result of the rest of the changes? Frames crack (Beta) Fuel tanks crack (Sherco)Gearboxes break (Gasgas), none of them have decent size petrol tanks and its a hideous job stripping bits off to get water out of the carb. Perhaps its time to have a rethink about just what we want from trials, maybe a minimum weight limit, ban magnesium and only allow thick weldable aluminium, decent cheap mudguards etc. As it is new bike sales are hrdly booming ? Cheers

Its been known for years that a Dunlop is a lot tighter on the rim than Mitchelin. This can be an advantge because you can ride it a long way after its punctured without it coming off the rim. Buy any tire a couple of weeks before you intend to mount it, put in an old inner tube and blow it up as far as you can without the tube popping out then hose it with hot / scalding water. Warm it up again (and the rim) immediately prior to fitting and they tyre will go on easier and seal easier. If you must lube it use tyre soap or silicone oil. Silicone oil is availble from plumbers merchant and used to make rubber seals very slippy. Cheers

In my view it was from sometime in the late 1990s that manufacturers started fitting poor electrics to their bikes, and not just Beta in an attempt to reduce costs. Perhaps only Yamaha / Scorpa have continually had decent electrics. I have had ignition components, stator coils, HT coils etc apart and quite frankly a lot are crap, poor design is compounded by poor manufacturing. Add to this the harsh environment, bumps knocks, pressure washing and rider abuse (like kicking the bike over without having plug HT led earthed) and its surprising more don't fail. The previous posters comment about gentle riding and airing the ignition is valid. High engine temperatures (Dougie on the Scott?) is perhaps the most certain killer of electric components. The insulating varnish on stator source and trigger coils starts to degrade at not much above normal running temperatures. Perhaps its time manufacturers moved from polyurethane to more temperature resistant (& more expemsive) epoxy insulating "varnish" and using all soldered rather than pressed together joints. Another move that would increase reliability is to move to a battery based system, electronics much prefer a stable voltage supply and it would mean stator components could be thicker wire better able to handle peak currents without over heating. Cheers Edit - just corrected a few spelling mistakes

I would not reveal full details on a forum but here is list of suggestions 1) Have PIR floodlights overlook where you keep it. 2) Install alarms so that they overlook the bike(s), the door (s) and each outer 3) A garage that is noisy - steel doors etc that is noisy to break into will help 4) Ground achcor and heavy duty chain through frame. 5) Personalise your bike by making discreet mods, then keep details and photos. 6) Using a set of hard stamps, stmp the registration or last several digits of frame number into parts such as hubs, yokes, swinging arm, sump plate, brake clipers, fork legs etc. Keep photos and a record. Use small soldering iron to discreetly mark plastic parts with same. 7) Ultra violet pen - but this may tend to wash off.

Assuming noise is not a problem, maybe 8 years old is time to switch to petrol, not up the voltage? 24V is 600 Watt and weighs 59 lbs 36V is 750 Watt and weighs 62 lbs Lifting front wheel is more to do with suspension characteristics and rider technique than it is with power I don't know what Watts (maybe 5000 to 6000) my sons Gasgas 50 boy is but its way quicker than either 24 or 36V. Cheers

Your petrol to oil ratio should be 25:1 (40cc oil to l litre petrol). Use standard mineral oil like Gulf 2T or Oregon 2T semi synthetic which meets the latest JASO FD specifications for clean running. Don't use fully sunthtic at lean (greater than 25:1) ratios. Plug colour, the porcelain centre electrode insulator should be a pale chocholate brown and dry, if not check timing then correct the jetting. If plug is OK and you are using above fuel mix just ignore oil from exhaust, means your engine is well lubed, better than too little lube. Cheers

Try raising the needle a notch or two. It sounds as if its just a shade weak just as it starts to come off the idle jet. If you can get one try a size larger idle jet. Perhaps go through your carb clening again with extra care on the slow running jet and passages to and from it. Check the number of turns ut of the slw running mixture adjustment screw. Cheers PS just had a thought - is your slide worn near the cut away, this cancause weakness just as throttle starts t open.

Get TY250 (air cooled) . Get an R model or Pinky with disc brake. If you want something bit newer get TYZ (water cooled) Take someone wth you who has owned one or knows what to look for. If you get a decent one it will last for years and cost very little to run. Quite a lot of the air cooled bikes may well be on their last rebore by now.

The "green moss" is what is left behind when modern petrols evaporate, many years ago petrols used to leve an oily yellow / brown deposit as they evaporated. As the bike runs for a while when you put petrol in the plug hole this suggests all is OK except the supply of petrol from the carb. The problem is 99% certain to be the small passages in your jets / carb body that are blocked with the "green moss" and unfortunately it can be very hard to get out. You need to strip out all the jets including pilot (slow running), main, needle, float valve, and starting / choke jet. You can poke them out with fine copper (NOT STEEL - it will damage them) wire. There are also passages in the carb body that have to be cleaned out, use fine copper wire, compressed air and carb cleaner. If you can't clean it out yourself take it to a carburettor / fuel injector cleaning expert who will have an ultra sonic cleaning tank. Cheers

To blow out an old fashioned steel pipe you blank off the ends and fill it with compressed air at between 100 and 150 PSI then gently heat the dint area until dull red. As you warm it it will slowly come back to its proper shape. The problem with titanium is that it reacts with oxygen over 250 degrees Centigrade, The hotter it gets the quicker it reacts and becomes brittle. To overcome this you fill it with argon instead of compressed air and use a large soft reducing (excess acetylene) flame and try not to expose the hot titanium to the air too much. Cheers

Anyone any thoughts on 2009 GasGas 125. Whats the power like - bottom end or revvy. Any reliability issues. Generally on 2006 and newer 125s which are rated best and which have known problems Cheers