dadof2

#7 " carburation is always spot on" I know what you mean even though they don't have a carb. I would however question if the fuel air ratio is always spot on. I watched some of the Richmond BTC at the section just above AGs house. On the BTC course a sharp blast up a steep soil mud bank and over a root needed a good burst of acceleration and revs. Both Billy Bolts Ossa and another ceased to accelerate properly on the final approach to the root. The engines made a dull blurty note a bit like a mix of 4 stroking and detonation. BBs bike clearly lacked speed at this stage.

Do your discs float? ie are they loose on the bolts. If so try putting some hylomar or similar gasket compound where the discs float on. Try putting copaslip or anti squeal compound between the pistons and the back of the brake pads.

If you are getting a C spanner consider one with the hinged end, It should then fit any trial shock you come across in future http://www.ebay.co.uk/sch/i.html?_nkw=c+spanner I have always been happy with gedore tools

Seems the FIM are taking action that may result in disciplinary action against some of the out of time riders

The jigs were made from heavy angle iron. They had holes drilled in one flange to suit cylinder base studs. The other flange was bored to suit a stepped bush that was held in with 3 socket cap screws. The flange boring and drilling was done with a pair of angles fastened back to back. One angle was then used on the RHS studs the other on the LHS studs.

You can leak test an injector with a foot pump with a pressure gauge. Connect foot pump to injector with clear PVC pipe with some petrol in. Keep pump above pipe so petrol does not flow back into pump. Pressurise to 50 PSI. Injector should not leak at this pressure. Note the above is a standard test for car injectors that usually operate at about 40 PSI (3 Bar). Check your RTs injector operating pressure and don't use a test pressure that exceeds it by more than a few PSI.

It would be interesting to see an actual factual comparison of reliability between old and modern bikes. Sure drum brakes are not as good particularly when wet but you are very unlikely to have to pull out of a trial because of a drum brake problem. You can strip them easily and fit a new cable in minutes. Bend or crack a disc, or have a problem with the hydraulics and there is usually little you can do about it at a trial. Points ignition rarely fails suddenly and is easily and cheaply diagnosed and fixed. I know it needs routine maintenance which is a nuisance, but I have seen plenty of riders stuck in remote places and facing a long push when electronic ignition just suddenly failed. Of course when it comes to riding in a modern trial the modern gasser is a far better tool than the old bulto, but if you want something a bit more versatile the choice is not so clear. Modern trials bike requirements has led design down a very narrow alley.

On a number of British bikes from the 1940s to 1960 where reaming of bronze little end bushes was required the following technique was used. Pieces of aluminium plate were inserted between the conrod and flywheels to prevent the rod moving from side to side. Crank could still rotate and little end could still move back and forth. A jig was then clamped to the crankcases using the cylinder base studs. This jig was fitted with bushes that were a precision running fit on the ends of an adjustable reamer. The jig ensured the reamed little end was exactly parallel to the crankpin / big end bearing. http://www.yelp.co.uk/biz/joy-engineering-motorcycle-camshaft-specialist-bishops-stortford You could try the above link. I have never used them but I know they do precision bushing. The two places I know who used to do this work have now closed. (old engineers retired)

One that fits your nuts.

http://www.ebay.co.uk/sch/i.html?_trksid=p2050601.m570.l1311.R1.TR3.TRC1.A0.H1.Xvacuum+bleede&_nkw=vacuum+bleeder&_sacat=0&_from=R40 See above link. As you can now buy vacuum bleeder kits for well under £20 there is no reason not to have one. Regular changing / vacuu bleeding of brake and clutch fluid prevents a lot of the problems you read about on TC

Perce & Dabster, since you are obviously so very intrigued by the capabilities of a 40 odd year old bike I will tell you of another advantage it had over modern bikes. It could be used for commuting in comfort and had a big enough tank to tour a decent distance.

Of course modern bikes complete the Scott, but a lot do get boiled, particularly in muddy years. For us mere mortals there are hardly any sustained flat out sections. If you reckon there is part of the course where you can run flat out for 4 minutes, do let us know before this years event, I am sure the outcome will be well worth spectating.

I would not use ATF either DII or DIII in a motorcycle transmission, It may give decent clutch action but it is very thin when hot and does not give smooth changes. Auto gearboxes for which ATF is designed are permanently engaged epicyclic, which is very different from a motorcycle gearbox. I would use an oil specially designed for motorcycle wet clutch transmissions, either 10w-40, or 75wt gear oil or something like one of the putoline recommended gear oils. Yamalube 10w-40 gives good gearchange and clutch action at a good price. I would not use 10w-40 synthetic intended for car engines, Some brands do dissolve the clutch plate adhesive on GasGas.

I stopped just outside the 30 mph limit. Apart from rear tyre and whole exhaust being very hot and smoking the bike was fine. In the places I practice we have some pretty long hill climbs and long bogs. On the old air cooled bikes (not just the Bulto) you could attempt them time after time. Try the same things on nearly any modern water cooled bike and you have to be careful or they boil, certainly 2 or 3 runs in rapid succession and they do boil. I am not suggesting a return to air cooled motors because piston / bore life and power output is much better on a water cooler, but because of small radiators and water pumps there are things they just can't do as well as the old air coolers.

Cycle and swim Avoid squats, they can damage your knees

Cold start enrichment, this is the device that lets a rich mixture get around the throttle slide to enable cold starting. It is not a choke (although some people mistakenly call it a choke) The fouling on your plug is dry, ie it is excess petrol. If it were excess oil the dark parts would look shiny not matt. 10 seconds of cold start enrichment should not do this. Check your air filter is clean, then check the float height. Then give the bike a good hot run with a new plug. Only after that start to change the jetting if the plug is still dark. You can't rule out a failing HT coil, source coil, poor connection or other fault in ignition circuit. Try disconnecting kill switch first.

I used to use sinisalo hard elbow protectors for MX, worked very well, even when I went down hard at speed on hardcore type surfaces.

The plug in the photo is carbon fouled. Do you leave your cold start enrichment on for some time? If not the carburation is a bit rich.

72 mph on a 250 Bulto? An indicated 72mph yes. Flat on the tank, full throttle, Racer SAE40 oil at 24:1. Fingers ready over the clutch in case the piston seized. At the end of the run the rear tyre (12 PSI cold) was too hot to touch and smelt of burning rubber.

http://www.wp-motorsport.co.uk/res/HTX740_uk.pdf Read the above - makes you wonder? This looks like an HTHS lubricant which would cause a wet clutch not to engage properly as in my previous post. However because a 4RT is low geared, has a low power output and a large clutch the lack of prompt full engagement is probably not an issue.

Dabster, and to a lesser extent Lucas, you need to go back and read my post carefully, not slang off what you thought I wrote. EG I did not use the word wasted and what I have said is true. F1 cars are slower than the used to be and in the 10 year period I quoted billions, have been spent trying to make them go faster. Dabster, The comparison between your Bulto and Gasgas is irrelevant to my post. The point I was making was that to club riders in my area bike fragility was of far greater concern than WTC. By the way I had a 1971 250 Bulto trials that could run flat out on full throttle at an indicated speed of 72 mph for 4 miles. Try that on your modern Gasgas. To get back to the main topic (weight).Most if not all the shortcomings and fragility of modern bikes is due to parts being too light and small. When I see the ease with which several club riders and lower level hard course riders can flick round a 77 kg 4RT on the spot it make me confident increasing the minimum weight a little will have no detrimental effect on the sport and if designers use the freedom to have more weight on the bikes to put a bit more strength in the right places it would be greatly beneficial.

Once one spoke is broken it puts a lot of extra lead on the adjacent spokes and they are likely to soon fail. take tyre and rim tape (if applicable off) and put plenty of penetrating oil on both sides of the nipple. You need a vice with aluminium jaw protectors or jaws fitted. By putting the wheel at an angle you can clamp the spoke securely in the vice jaws. You can then use a srewdriver, mole grips or a securely fitting adjustable spanner on the spoke nipple. Work the nipple gently back and forth to free it off. Nipple threads may need cleaning out with a tap, I think threads are M4 If Gasgas do not sell individual spokes do a search for wheel rebuilders etc. You can usually replace one spoke.

A far as I know its still on, 0900 start. Ring AM Stewart to check if you need Tel 01228 526 858 ​I know they were leaving list as late as possible due to lack of riders and observers. Unfortunately the Alan trial clashes with an extremely popular nostalgia scramble only a few miles away

There are at least two reasons why some synthetic or semi synthetic engine oils in particular should not be used in wet clutches. Firstly some contain High temp, high shear (HTHS) additives which prevent the clutch engaging fully, leading to extended slip periods after engagement. Secondly some of the cleaning / dispersant additives dissolve the adhesive that bonds the linings to the plates. When buying car engine oils you do not know what exactly is in them, but as both Castrol and Mobil produce wet clutch (motorcycle) varieties of their synthetic engine oils its a fair bet they are designed to avoid the problems I mentioned.

Nigel - the F1 cars are not as fast as they were EG. This years monaco fastest lap was 4 seconds slower than Schumakers 1994 record. Bike fragility - no one mentioned weight or wanting to ride a B40, but there were numerous moans about lack of reliability. Here is a sample of items. Sherco rider, bike about 3 month old, brake and clutch hydraulic problems, Gasgas riders dad, has had to rebuild his sons gearbox twice this year after minor gear lever impacts on rocks. Beta rider, misfire and lack of power (probable coil failure). Another Beta rider, exhaust leaking at barrel after lightly catching exhaust on rock. There was a general consensus that the TY250 monos were best, this comes up time and time again, I note that one of the aims of Jts JTS is longevity, lets hope they achieve it and the other manufacturers follow suit.