dadof2

Just thought I would post this as an example of an intermittent fault that becomes worse as the components warm up, typical of HT coils, regulators and ignition source coils. The first trace in blue shows the output from a regulator that was suspect. In this case the fan would run but not as fast as it should, and once the bike got hot may not run at all or need a flick of the finger to start it. As you can see the pulses above the line are irregular. The spikes below the line are typical of partial diode failure. From this one trace it is not 100% certain regulator is at fault, could be a loose wire or faulty ACG coil. Now a second channel (red trace) is connected to the ACG output. As can be seen the out put is good and regular but as the regulator has warmed up it is less frequently converting the ACG output into DC (pulsed) to drive the fan. A check such as the above with an oscilloscope on all a motorcycles electrics could be very worthwhile before events such as the Scott or SSDT. regulator fault.doc You will have to view the attachment in Word at 200% to see it properly

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/328677/INF85_240614.pdf This will help get your stolen bike back. If you engrave or hard stamp the Reg No on plenty of parts it makes theft much less likely.

I once made a small aluminium case a bit like a silencer and fitted it in same place as silencer on opposite side of bike. I think some bike had this a standard but I can't remember the make, may have been a trail bike rather than trials. Mont 348 was best, proper toolbox under seat.

What 2T oil are you using and what ratio? Is rattle worse hot or cold or does it reduce when you pull the clutch in?

http://www.demon-tweeks.co.uk/Product.do?method=view&n=465&p=512993&c=215&utm_source=Google&utm_medium=Base&utm_campaign=2%20Stroke%20Oils&gclid=CO2y_oq6h8MCFUbMtAodi14APA Originally these old air cooled engines used a SAE 40 or SAE 50 2T oil because of the large piston / bore clearances. Modern synthetic 2T oils tend to be much thinner (SAE 20 to SAE 30) but have high thin film strength. Castrol A747 as above is a good high viscosity oil as is Shell VSX. Bardahl do a high viscosity 2T oil but its about £30 a litre. I would be inclined to use the Castrol at about 30 or 40:1 but you could use something much cheaper like gulf pride 2T (less than £10 for 5L) at 24:1 You could use any good quality synthetic oils at leaner than 40:1, your bike won't seize but it will rattle a bit as these oils are meant for close tolerance water cooled engines. A747 is meant for very high performance water cooled engines but it works well in anything.

That is the question that will be engaging quite a few minds after his Sheffield domination. Bou's Honda may be good but if it were really much or even any better than the 2Ts Fuji would do better, so its a fair bet Bou's domination is down to rider ability. Pretty well all the top riders can balance as well as each other but Bou seems to be able to find a bit more traction particularly at the harder obstacles. They are all presumably on the same tyres and similar pressures. The difference between Bou and the rest would seem to lay in body positioning and throttle control. When applying scientific principles to other sports great use is made of videos and computer analysis. If I were a manager of any of Bou's competitors I would be trying to find such people. By analysing all the data from videos and sound recording of RPM etc it should be possible to identify where Bou's advantage lies. Whether the others can emulate it is still open to question but at least they may have a better idea of what they need to work on.

http://www.mrsltd.co.uk/documents/IponeRetailPriceList2013.001.pdf

What cc is your engine? I can give you a good approximation for the timing from this

#99 "I told you so, I would have more sympathy than use this comment to a 4RT owner who had the misfortune to have EFI failure, I reserve the use of that phrase for owners of a marque well known to be prone to gearbox failure Honda EFI does seem to be pretty reliable, but its a very simplified form of EFI and compact. Honda electrics are probably about the best in the industry but they still go wrong and can be horrendously expensive. I presently have six hondas (not trials bikes) dating back to 1978 and none has ever needed an electric part, But on the other hand I have owned other hondas and have HT coil and regulator failure within a few months of new. In any case to make a 4T competitive it probably has to be EFI. To avoid poor pick up just off tickover carbs have to be too small bore to allow the engine to rev properly or they have to be CV which don't work consistently when subjected to up and down movement. They may mostly be able to cope with club trials and easier national sections, but subject a CV carb to arena X trials or some WTC type sections and very variable running will result. Adjusting for clogged air filter and humidity. One of the key advantages of EFI should be its ability to self adjust for variations in input parameters. If it is incapable of doing this it removes one of the main potential advantages over a carb. A clogged filter does not have to be due to lack of maintenance, it can occur in the middle of a trial a long way from back up. Possibly this is why Ossa has made the effort to have a pretty good filter that is not prone to getting dirty or wet. The $10 tool. I note the article says "you do this at your own risk" It is all to easy to trash an ECU doing this sort of thing, carbs are far more robust and cheaper to fix if it does go wrong. A significant improvement to 2T running, engine wear rates and emissions reductions (possibly greater improvement than EFI with premix) could be given by using a pump to provide engine lubrication and running on straight gasoline but when Yam did this people removed or disconnected the pump and resorted to premix with its drawbacks. An oil pump would also be much cheaper than EFI.

Most points ignition bikes can do this, seen several Bultos do this bouncing back off steps in CCMCC Alan tropy trial

This is an inherent problem with single cylinder 4 stroke engines, probably the reason Mont / Honda went EFI with the 4RT. The cheapest solution is to find a secondhand CV carb. One of a Kawasaki KLX 250 should work Ok with a few jettng changes. If you can't get one of those a CV carb off a multi cylinder road bike should do. try to get one where the carb serves a cylinder of between 200 and 250cc. Beta use Cv carbs on their 4T trials bikes so it may be worth trying one of those if you can borrow one.

Agree with #3, I was in middle of writing when he posted. Intermittent or poor hot starting can be a sign stator source coil or HT coil is beginning to fail. Resistance readings can be a clue but are not always decisive. An check with an automotive oscilloscope is the only way to really check. You can get a good spark at the plug out of the cylinder but it may not be sparking when under compression.

If the bike is going to be ridden at sustained high throttle openings consider richening the jetting until the plug is a darkish chocholate brown. What oil ratio are you using? It could be the rings / bore are a bit worn and low on compression with quite a bit of blowby when really hot. This would make it hard to start. Occasionally a faulty source or HT coil can cause poor starting when they get hot.

Hi, Please don't take offence at what I am about to write. Unfortunately I can't advise you about the fork internals. I suggest you (once forks are fixed) leave the suspension as it is and try getting some weight off your son. Get him out on the trials bike often, plus some mountain biking and cut back on the worst foods. 1 & 1/2 to 2 stone should not take long to shift and he will feel and ride a lot better for it. Riding any off road motorcycle whilst too heavy is near certain to lead to knee problems. Long term you will save quite a bit of money by not having to mod suspension and less wear on the bike.

I have no problem reading car number plates at the required distance without glasses but find I need them for fine detail close up. I need glasses to pass the eye test for a MX licence but that eye test is done at about 5 metres in a surgery and is nothing like what you need to see in a section or on the track. No way would I wear glasses in competition, give me a hint of blurring over distance distortion anytime.

0007 #18 Regarding WD40 I witnessed an amusing incident several years ago at mx. A rider accidentally fuelled his bike with Contect Duck oil, which is very similar to WD40. He already had some 2T mix in the tank and carb so the bike started and ran OK. After about a minute on the start line it started to smoke a fair bit then the race got underway. The rider did the whole race (15 minutes + a lap), the bike was pouring out clouds of smoke and stank of paraffin / kerosene. After the race he realised his mistake and changed the fuel. The engine was unharmed despite having being worked hard round a hilly sandy track. #20 What is TCC? If you ride the bike swiftly and do long hillclimbs 50:1 is as lean as you should go. For pottering about and gentle trials type going 75:1 will be OK. Castrol do not advise leaner than 65:1 even with their best synthetic oil and many oil manufacturers mark their products advising that 50:1 is the leanest ratio you should use.

#91 My comment hardly justifies your use of the word police. I asked the question because I wondered if atomant was showing early symptoms of "Mary Whitehouse syndrome" Back to EFI see the following (caution its a long read) http://www.remmington.info/advice.htm. This pretty well outlines one of my objections to EFI, the lack of compatibility and expense of diagnostics equipment. I am aware of a couple of car EFI problems at the moment. In one case the manufacturer never sold the diagnostics equipment, it was leased to main dealers at significant cost (circa £6,000 per year in about 2010). Most main dealers no longer have regular need for this diagnostics so no longer pay for it. This means anyone with the affected model of car has to travel a long distance (well over 120 miles from my area) and pay £70+ per hour for what should be a 5 minutes diagnostic job. On another vehicle which is supposed to be OBDII compliant, 2 OBDII DTC scanners have so far failed to communicate with the system. These are the sort of unfortunate experiences that lay in wait for owners of EFI trials bikes when they go wrong, which they eventually will. Perhaps it will be the case that EFI trials bikes should be regarded as disposable goods, you expect a few years reliable use then at the first instance of an expensive repair you bin them like a washing machine or break them and sell the good bits for what you can on Ebay. Take a look at CCMCC new years day results, won by a twinshock suzuki, do trials need high tech? EFI trials bike so far only measure air pressure, which means they can adjust to suit changes in pressure due to weather and altitude. They do not however have MAF sensors which mean they cannot adjust for changes in humidity or air filter resistance both of which are significant factors in trials bike fuelling.

Have a look at historic posts on this topic. Why not just stick to manufacturers recommendations? The fact that you have felt it necessary to ask this question suggests you do not have the knowledge to know the implications of not following those recommendations. There are advantages and disadvantages to using different mix ratios but it is not a straightforward issue.

Atomant #87 - why bother to read it and post if its painful? Fuel density, because fuel is pretty incompressible then is should follow that its density can't be changed that much. And that is correct when you are talking about mass per unit volume as the measure of density. However when you are talking about weight per unit volume the effective density varies with gravity because weight varies with gravity. That is how a centrifuge works, by increasing the g force and increasing the effective density of the materials in the centrifuge, causing them to separate. To make EFI work Honda /mont has to use quite a complex system of capacitors, Ossa had had to fit a battery and now it seems Vertigo are to do the same. Perhaps its time to ditch the troublesome fine wire ignition source coils (that date back to at least the 1960s) and have homogeneous thick wire coils in the alternator (ACG), a decent rectifier / regulator and a proper 1 or 2 Ah battery. This would give the fan and electronics a far easier time and give reserve capacity so bike could keep running for some time even if ACG failed.

I don't know if these have fixed or electronically variable timing. If it only has a fine wire source coil it is probably fixed, if it has a separate trigger it is probably variable. I would mark the flywheel at about 3mm and check the timing is about that with a strobe light. Next I would mark the throttle at 3/8 open and ride it up a long hill several times with it pulling steadily at that throttle opening, then check plug colour to see if mixture is rich or weak.

Regarding the floats, Copemech has confirmed my thoughts. This is the way I pictured it, suppose you ride the bike off a 1 m high boulder, initially it accelerated downwards at 1 g and floats and fuel are effectively weightless, then for last 160mm it decelerates at about 6g, Therefore floats and fuel effectively weigh about 6 times as much as normal. Normally the floats have a (a bit loose on the exact physics / terminology here) density about 1/3 that of fuel. Take fuel as 7 gms / cm3 and float as 2 gms / cm3, multiply this by 6g and the fuel is now 42 gms / cm3 and the floats 12 gms / cm3. The ratio of float density to fuel density remains the same so it could be expected that the fuel level / float displacement remains constant during the drop off and land manoeuvre. Be interesting to see exactly what happens if anyone had a centrifuge, a clear float bowl, floats and a high speed camera. On the subject of 4RT cut out at low RPM. Does anyone know at what revs this happens and for sure if this is due to lack of electrical power to ignition or EFI. I wondered if valve overlap could be a factor. When valve overlap is sufficient to give a wide spread of and decent top end power it often results in rough idle or cutting out at low RPM.

http://www.geocel.co.uk/catalogue/single-brand/trade-mate-range/trade-mate-lead-and-gutter-seal See above, I have posted this before. Do away with rim tape and coat the well with 2 to 3 mm of the above. Fix any loose spokes first. Leave overnight to fully cure the put a layer of PVC tape on to stop tyre damaging seal during fitting. Replace the valve with a bolt in type. Instead of the above sealant you can use sikaflex windscreen adhesive but DO NOT use acetoxy type silicone or the acetic acid in it will severely corrode the rim and spokes. I did a rough corroded 07 Beta rim using this method in March and it is still sealed.

http://www.trialscentral.com/forums/topic/53920-carb-leaking-fuel/ "Think of this! When you land off a large rock the weight of the floats push quite rapidly down inside the float bowl. This is known as gravity. The extended movement of the floats downwards tends to do two things. It moves the floats way down inside the float bowl allowing more gas than needed and it also causes some of the excess gas to be pushed up into the jets and into the engine" The text quoted is taken from #9 of the link above it. Do the floats actually do this, anyone any thoughts?

ND I do not mind anyone disagreeing with me or having a different point of view but at times you make statements that are just not true such as saying I do not own a Gasgas or accuse me of not knowing anything about them when you have no means of knowing whether I do or not. The FACT is I own 2 GGs and have worked on or helped diagnose problems on several more recently. If someone does have a different point of view I ask that they put forward a reasoned argument, not just say I am wrong. I and anyone else is fully entitled to post what they like on this forum no matter how tenuous its link to the topic. It is up to the site owner and moderators to manage the site as they wish, not have unofficial self appointed "moderators" say what should or should not be posted. Am I really on nights?

ND #37 You really do spout some crap especially when you make judgements on things you have not seen. RE the novice on the 200 Beta. He actually did it twice not just once. The only way anyone was going to get all the way up the hill was in 4th. On the first lap the novice got into 5th by mistake. After seeing what happened to the others he did it deliberately on the second lap with the same result. The same novice went on the be a club clubman class champion and won a trial outright recently. Finding grip is to do with both throttle control and power output / engine characteristics anyone who ignores any of these factors is going to be less successful. The fact is in the circumstances I described the 250 4RT comfortably outgripped the 300 GG 2T and required less rider input to do so. The limestone step at the end of the section was only about 18 inch to 2 ft high so the bike could be nudged over it at low speed. Had it been a bigger step needing a faster approach it may be that the GG 300 in 3rd would have come out better than the Mont 4T in second. I doubt if the 250 could have managed it round the tight corners in 3rd. The point I was making was not about throttle control but about how a lower powered bike can be easier on the rider. This was noted in a Beta test last year when the consensus was the Beta 4T were less tiring to ride up the clubman level river sections than the Beta 2Ts. The test was in a magazine whose name cannot be mentioned on this Forum