dadof2

Perhaps the manufacturers could shed some light on why they have switched to shielded / sealed main bearings. I wondered if it was to increase crankcase compression or to enable leaner oil to fuel ratios to be used. Sealed bearings do last many thousands or running hours in industrial applications but usually at lower temperatures than 2 stoke crank cased and without the vibration. Cheers

I agree, it really is infuriating the prices charged for some spares and the fact you can't buy just the bit you need. I reckon if one of thre top manmufacturrers improved their reliability a bit and had a fair spares price and availability it would only be a few yers before they dominated the market. Cheers

Even Toni bou got this one wrong and had to jump ovr the bars. Absolutely brilliant trial to watch Really good to see how well the brits rode, Dabil on Sunday podium and Browns ride up the rock face, section 8, on Saturday was stunning. Cheers

I would find a garage with a PICOscope or similar. All they have to do is clip a sensor on the plug lead whilst the bike is running and they will easily be able to diagnose if its an ingnition problem, and if it is almost certainly which component is at fault. Cheers

I agree with Chris Morris, but you might find it is aluminium corrosion not dirst. Pacvk some wire wool into the groove and worl it round polish the groove out. I am not familiar with Mont calipers. Seals have a taper on them so that they have a lrger outside diameter at the pad end. Mostly on trials bikes this taper is achieved by the base of the groove not being parallel to the pistion bore but occasional the base of the seal groove is parallel to the bore and the seals are not rectanglar section. If you have tapered seals and put them in wrong way round you get the problems you have. Cheers

I would think very carefully before drilling through to the inside of an air box. If you do make sure whatever you have on the inside won't fit through your reed block. Nuts and other thingies don't mix well with two stroke ports and pistons. Cheers

Totally agree with paul w. I have seem quite a few spacers shorter than they should be. They are too soft and have too little diameter to properly support the inner bearing race. Cheers

From memory (sold my TY 250 in 1995) the top inner bearing should be above the frame to give clearance under the dust cap. This is a thin pressed tinny thing, a dark green / olive colour. Can't realy remember the lowr seal, I think it fitted round the bearing on the bottom yoke. Cheers

Why not make up something with a castor wheel on that can be bolted in in place of your from wheel, then you can turn the bars / mudguard any angle to push it in. A friend of mine has just made one for getting a 600cc Honda road bike into a Bedford? camper van. That was more to do with height of the fairing, height of doors and angle of loading ramp than door width. His has 2 castors with 150mm wheels about 400mm apart. Cheers

Beta technos had double skinned pipes - made them a sod to repair / blow out. Many large capacity 4 stroke road bikes had double skinned pipes - to preserve the chrome. Lagging your exhaust won't make hardly any difference to to the revs it works best at, it will just make it work better at the revs it was desiged for as it preserves pressure wave energy. Trials exhausts are a long long way from optimum power design anyway. I would think making the torque curve appropriate to trials use, reducing noise and keeping the exhaust as compact as possible are the main design aims. Cheers

Putoline recommend Ester Tech Syntec 4+10w40. and I would agree with this. If you use another make of fully synthetic 10w40 make sure it is compatable with wet clutch use. Smith and Allan supply a fully synthetic 10w40 which is compatable with wet clutches and cheaper than putolne. Mobil 1 10w40 should be OK. I would advise againt automatic transmission fluid (TQF). They are far thinner than 10w40 when hot and do not have the same oil film strength. To cut oil costs (fully sunthetics arnt cheap) you can reuse oil several times, drain it out and let it stand for a week, all the debris settle to the bottom and you can reuse the upper 3/4s, use the rest to lbe you chain Cheers

I have only ridden Shercos 2006 and newer and then just for a few minutes practice, not a full trial. My impression is the 290 will spin the rear wheel easier and you have to use body positioning more and work harder to get the best out of it. Both will lift the front wheel with ease and controlably - is your 290 carburated properly or is it too rich or too lean just off idle. Check the handlebar positon, footrest position and tyre type, condition and pressure are same before making comparisons. If the 290 is loosing grip because of sharp botom end powr fit an extra 0.4 mm of cylinder base gasket and go lean of the idle jet. Cheers

Try Nigel Birkett at Birkett Motorsport Cheers

Only on an old BSA and a Husqvarna unfortunately. From what 211s has said I think you will take the power from the services - the low ohms being due to the thick windings. Connect up your bulbs in parallel and fit a voltage regulator or it will blow bulbs at high rpm. I know on my husky I always had problems with stop bulb blowing even with regulator fitted. I put this down to the shakig it got under braking on rough ground. To preven this I fitted a switc to isolate the brake circuit when I was off road. Cheers

Perhaps the best over the counter / stock competition bike ever made in my opinion. Competitive, very well made and reliable. They have one drawback if you are going to ride them hard (sustained WOT). The coolant enters the cylinder at the rear of the barrel, whereas most heat is generated at the top of the exhaust port. This causes a steep temperature gradient and distortion across the barrel. Normally at motocross this is not a problem but if you use the engines for supermoto, grass track or beach racing in is well worth modifying the cooling system to give much more flow around the exhaust port. Cheers

Some rattle is normal but If the noise changes or gets worse don't ride the bike until it has been stripped and examined, you could do expensive damage. I know of a pro just over a year old on which the rattle suddenly got slightly worse but he kept riding it for the rest of the evening. One of the tiny rollers on the clutch release bearing came out, damaged other parts then bits off them damaged yet more. The bill? well over £600. Cheers

I guess you are talking about ignition? I have no direct experience of an 2012 300 but can't see it being different to earlier models which have a source coil (a large coil with a lot of fine windings) a trigger coil which is a smallblack thing with a small piece of exposed metal. Usually the source coil gives about 20 to 30 volts AC when you kick it over and has a resistance of 200 to 300 ohms. The trigger coil usually gives about 1.5 to 2.5 volts AC when you kick it over and has a resistance of 1000 to 1250 ohms. You need a digital multimeter to check this or an oscilloscope. Analogue meter(swinging pointer) does not respond fast enough. The best way to check these outputs is with plug out, connected to lead and earthed on cylinder head, carb and reed block removed and spin the engine with a drill. Ideally look for output with an oscilloscope (many car garages have these). Cheers

Thaks for replies, it quite likely the case that up here with a lot of rocky sections riders frequently snag the gear lever. Having said that there seems to be quite a few gearbox problems that are not linked to selector or kickstart. Cheers

This is not having a go at Gas Gas its more of a survey for my own curiosity. I was just having a think and I do not know of any Gas Gas pro above 125cc and over 3 years old that has NOT had to have its gearbox rebuilt. For some reasons 250s seem worst affected and I know 3 of these that have had to have he gearbox rebuilt twice before their fed up owners sold them Am I alone in my observations or is gearbox failure as common as it seems to me? Cheers

Regarding the little end - how much oil do you put in your petrol. I get a bit of flak on this forum for my view that 70:1 is far too lean a ratio. I think 30:1 or 40: is muchg better. How well do you look after your air cleaner? In my view the gas gas gearboxes are a bit near the limit of light design and need good oil, frequently changed to protect them. Some peole use ATF Dexron II or Dexron IID which is in my opinion not up to the job. Dexron III may be better but I would go with Putoiline recommendation of Ester tech 10w40, or maybe their gp nano transmission oil. If you drain the oil frequently you can let it stand for any bits of metal or clutch particles to settle out then re use the upper 2/3 or 3/4. Cheers

I think 4th to 5th and 5th to 4th shifting problems are an early indicator of a needle roller bearing on a gearbox shaft beginning to fail. Better sorted sooner than later before it damages anything else. Cheers

0007 reply 78 - I cant agree with your statement that piston deposts have nothing to do with the oil. An engine with the carburation spot on will have heavy deposits if castor oil is used, use mineral oil and the deposits will be less, use a modern FD spec semi or fully synthetic and there will be virtually no deposits. I know pepole use piston deposits as a tuning guide and many years ago have done so myself on kart engines when we used castor oils. I was at a kart track a few weeks ago, a lot of the competitors were using shell advance racing M at 16:1 and there were no deposits to see, just a greasy coating. The comment that someone made abut Jeremy Magraths CR250 not smoking at 25:1 shows that with right oil and set up rich oil ratos run clean. I run my CR500 at 20:1 as per Hondas recommendation, it starts, pick ups and revs out no problem. The piston stays clean but there is some oil dribble from exhaust. Talk about stociometric ratio on trials bikes is a bit of a waste of time. Most of the time they need to be well rich of stociometric. If you jetted your bike spot on for the start of a trial, say 500 ft above seal level and 8 degress in the morning, come the afternoon and you may be at 1200 ft above sea level and the temperature well over 20 degrees in sheltered rocky sections, the air density will have dropped well over 7% and you will be running far too rich. Atmospheric pressure also varies by frequently as much as 5% over a few days. (965 to 1015 mBar) Getting back to the original question, more oil gives more power and less wear, deposits are not an issue, the only potential downside is you spend a bit more on oil. Cheers

Ring the dealer you bought it from and ask, if he is not helpful ring Malcolm Rathmell at http://www.malcolmrathmellsport.com/ If they don't help then contact trading standards at your local council. Goods must be of merchantable quality and fit for the purpose for which they are sold )1974 sale of goods act) Any reasonable person would expect a kicksart to work propelr for several years at least so long as you have not done anything unusual to damage it. Cheers

A statement I definitely disagee with is 0007 "This will put carbon on the crown". Some modern oils meeting Jaso FD spec leave virtually no deposits whatever the combustion conditions. The jetting and conbustion temperature can be spot on and provided there is adequate oil film between the piston and barrel to conduct the heat away from the piston deposits will not form. (Suprising how many expensive oils don't meet FD spec) Amsoil probably is a very good oil but I remember in about 1978 a friend put it in a 6 month old Mont 348 at 100:1 and within 10 minutes running the a main bearing seized. Bke had previously run fine from new on castrol TT at 24:1. If you look at the mix ratios logically you have a range of ratio recommendations (with good fully syntheics) from 15:1 for kart engines to 75:1 trials bike manufacturers and 100:1 some riders and some oil suppliers. As a general quide wear and stress in an engine increases at the 4th power of speed, ie doubling the engine speed results in 16 times stress and wear. Add to this the temperature increase effects and the actual increase is more than to the power4. From this it follows that bikes trickling round 1 mile laps with tight nadgery sections will have significantly different oiling requirements from one doing 10 mile laps on boggy fells with big hills. The worst that can happen with a rich ratio is a bit of fluffing on pick up after some nadgery slow going. The worst that can happen with a lean ratio is an blown motor, an long push and an expensive rebuild. Its your choice as they say. Cheers

Looks like your exhaust has had a lot of old oil and some unburnt petrol in it and in the packing. A good run out on the road has got the exhaust hot enough to set the old oil on fire. If you look in you might find your packing has been smouldering. Cheers