trapezeartist

The fact that this thread is getting so many contributions shows that we are concerned about safety. But no-one on here has suggested there should be more rules. It's just an opportunity to discuss what we might each do to improve our own personal safety. (Or that clubs might do, in the case of first aid kit, first aiders and suitable briefings.)

Having a dig at one of the finest counties in England is a bit rich coming from someone who lives in the land of roundabouts and concrete cows. So, getting back to the point: trials bike manufacturers seem to have no problem in persuading us to buy engines operating on the "obsolete" two-stroke cycle. Therefore there should be no problem is persuading us onto an "obsolete" valve arrangement if the design were shown to have technical merit for the very particular application of trials.

The OP has raised a valid point, but it would be nice if we could get a few sensible precautions in place without compulsion. Lanyards: What's not to like? As well as being a small aid to safety they are also handy for making sure your bike doesn't rev it's nuts off when you fall off. Gloves: Unlikely to save you from any serious injuries, but a lightweight pair of gloves will provide some protection from gravel rash without affecting your ability to ride. First Aiders: In a trial with 60 riders, 10 observers and a couple of organisers, there will surely be a few people who have a valid First Aid at Work qualification or equivalent. It's just a matter of making sure everyone knows who and where. First Aid Kit: A modest first aid kit at a central location (signing-on od Section 1) would be handy but probably not life-saving. In the very unlikely event of a life-threatening incident, the two key items would be BVM and a defibrillator. These are items that fall within the skills of a first-aider and the BVM costs very little. An AED is a bit more but prices are coming down. Full-face helmets: I find it very hard to argue against facial protection, but in reality I'm prepared to take the risk because I don't want to wear one. I can't justify that choice; I just don't.

Golden Valley CMCC have a defibrillator at the start of section 1. A step in the right direction, provided everyone knows about it, especially given the more advanced age of the average rider at classic events. Having a person trained to First Aid at Work level and accessible on a known mobile number would be a useful asset at any trial. Not difficult or expensive to arrange.

My old 4 speed Bultaco would do it whenever the revs dropped low enough (no idle). The first time it happened was at traffic lights (I used it to get to school sometimes) and it came as a bit of a surprise. Fortunately I wasn't attempting to out-drag anyone. After that I could do it almost on demand, and re-reverse it too.

Nigel, I'm afraid I have totally failed to understand your metaphor(s).

Sounds like my story too. Whereabouts in Somerset?

Item location: Middlesbrough Seller location: Cloud Cuckoo Land!

Every "mass market engine" starts off as a niche market engine. If the niche engine proves to be what the buyers want, it becomes a mass market engine. In the world of high volume cars, the current trend is to small capacity, turbocharged direct injection (stratified charge) petrol engines. My present car has just such an engine which has the same fuel economy and performance as my previous diesel, along with far better refinement and presumably less NOx and particulate emissions. No engine in a trials bike is "mass market". If a side-valve engine proved to perform better in this unique application, the specialist engine manufacturer could readily develop such an engine at sensible cost. I would like to think that trials bike customers would make a more rational buying decision than the average car buyer, and would happily accept an engine that shares certain characteristics with an Austin 7 and a Ford Pop in order to get the performance benefit. It would still require a degree of marketing on the part of the bike manufacturers though.

I signed.

Yup, I think we're all with you there.

The reed valve appears to allow the crankcase to pressurise, but relieves a depression. Could the reed valve be something to do with the oil system. If you allow the crankcase to build up pressure, that pressure could be used to scavenge oil back to the tank (gearbox?) without needing a scavenge pump. I'm not familiar with that Honda engine but I think I remember someone saying the same oil lubricates engine and gearbox.

That is a really good idea. Years ago I made a torx key out of an Allen key with a bit of judicious grinding, in the days before torx bits became readily available.

So not everything is bigger in America, then.

I don't understand this either. Clearly there is a lot of pumping going on in the crankcase of a single cyclinder 4 stroke. A volume equivalent to the swept volume needs to be pumped in and out of the breather every stroke. If the breather isn't big enough there will be a fluctuating pressure in the crankcase. Adding a one-way valve simply means that the breather flow in one direction is enhanced. I can see this being a benefit for stopping the engine pumping oily fumes out through the breather, but I don't see what it does for engine braking.

Buck is slang for a dollar. A quart is an archaic measure of liquid quantity, along the lines of furlongs, firkins, poles and perches.

Any good?

If you suspect the tapers are not as good as they should be, lap them together before finally re-assembling. Leave out the key, smear som grinding paste on the shaft taper and then oscillate the flywheel on the shaft. After a few seconds of that you can wipe the paste off and inspect both tapers. If they're a nice even grey, the job is done so just get on and assemble. If not, put more grinding paste and work away until you have got to near 100% contact between the two tapers.

Is the 4x4 on the short wheelbase or long one?

Countyist! Drifting off the subject slightly, but if world-class or even national results could show us the hierarchy of the "best for an expert" trials bikes, I still suspect that the hierarchy of the "best for a clubman" trials bikes might be very different.

Citroen Berlingo or Peugeot Partner seem to be the obvious choices for a bike-carrying van. However a lot of the older/cheaper ones are in an awful state as they seem to appeal to builders. I've noticed a few nice Renault Kangoos advertised which look to be in much cleaner condition. Perhaps they appeal more to flower shops and the like. Has anyone used a Kangoo? Does a bike (just one) fit in OK?

That may or may not be true. But if Tony Bou won a trial this weekend with a banana stuck in his left ear, we'd all have a banana in our ear next week.

What's the engine?

Wakka, it's just a wild guess but I think he might be in Dumfries.

Purchase valve cores? I thought you just had to pick them up off the floor at the local tyre fitters.