trapezeartist

Good point about the engine running backwards, SectionSwept. My Fantic does that occasionally at the moment. The improved chuggability (is that even a word?) of the exhaust restrictor is attractive and I would guess it would also balance out any top-end boost that might come from the higher ports. Provided there isn't a heat issue (and you guys are reducing my concerns on that score) it sounds promising. I've just been doodling some calculations and it looks like a 1mm extra base gasket lowers the compression ratio from 9.0 to 8.0. That sounds about right. Easier starting would be a bonus too. Costs of the two compression ratio options are closer than expected. Assuming the head has to come off to change the base gasket, and the engine will end up with two base gaskets, that's going to cost about £70. A low compression head and head gasket will cost about £85. Whatever ends up being the solution, I fancy buying a 250 will be the way to go. Unless a good 200 lands in my lap.

Has anyone ever made sense of the quoted compression ratios in the official Beta specs? 125: 15.9 (totally unbelievable!) 250: 9.0 300: 10.9 200: different again, but I don't have the info to hand now

An extra base gasket is obviously similar to a low compression head. As well as affecting compression ratio, it will also increase the squish clearance which will also be good for softening power. It will raise the port heights too. I'm struggling to get my head around what that will do. The higher exhaust may reduce power as the last bit of pressure will be lost. Higher transfers might reduce low speed power and restore a bit of top end. Am I right? Richening it up is an interesting idea. As an ex-karter, I'm naturally disposed to running as lean as possible so I'm going to have to rethink this a bit. How did you do it? Main jet or needle position?

I've played with quick and slow throttles on another bike. When I was an even rawer novice than I am now, I thought the slow was good. But then I found that occasionally I wanted a good handful of throttle without needing to move my wrist too far. So I'm not a big fan, but it's a cheap mod and I would almost certainly give it a try. Washer in the head pipe, nhuskys? Do you mean the exhaust? I would be a bit concerned about the back pressure and the effect it might have on cylinder temperatures. And I would certainly expect it to affect carburation. I had thought about a restrictor in the inlet, but that's really no different to adding a throttle stop. And a throttle stop is not much different to a slow throttle where it becomes impractical to wind it all the way round. These are the reasons I was thinking about low compression or retarded ignition. They would hopefully tame the engine all the way through the rev range.

There's a general consensus around these parts that the Beta 200 is the ideal bike for novices and other riders of limited ability. The trouble is, in the secondhand market, 200s are as rare as virgins in Essex. So I got to wondering what it would take to tame a 250 down to 200 level. You can get low compression heads at modest cost. How much difference do they really make? What about retarding the ignition? For sure it would reduce peak power to a manageable level, but would it then hurt the responsiveness or the ability to trickle around on next-to-no revs? Is it even possible with the CDI ignition?

I take your point. I've worked in vehicle safety too (claim to fame: I've crashed more Deloreans than anyone else in the world) and the prospect of anything heavy flying about inside a crashing car is scary. However, we all have to pick our risks otherwise we would spend all our lives in bed and then worry about whether the ceiling will fall on us. We're motorcyclists: we can't be that risk-averse!

Blimey. Minivan? One of those Jap things used by florists?

You make a very good point. Any method of fixing your bike needs to have some redundancy ie failure of any one strap or component doesn't lead to catastrophic results. If I were carrying a bike on a trailer I would use at least three straps (probably four) so that failure of one strap wouldn't let the bike fall over/off. As I carry my bike inside a van-like car, I don't need extra straps. If the bike falls over, it can't go far, and it certainly can't end up sliding down the road.

Are you really sure your bike won't go in? I carry mine in a Citroen Berlingo car (with the rear seat removed and the passenger seat a little forward of normal). I've seen people carry a bike in a Renault Kangoo too. I can't imagine there are many vans smaller than that.

I share your concern but for slightly different reasons. The 70kg is a static limit that makes a sensible allowance for dynamic leadings. I once had a largish 2 axle trailer. The static nose load was quite modest but over bumps it yanked the back of the car all over the place. It never did any damage, but I got rid of it pretty quickly just in case. My concern is insurance. If your limit is 70kg and you put a 65kg bike on, plus fluids, plus rack, plus mud, you are exceeding the limit. If you have an accident you insurance company will be looking for any excuse to not pay out. And you just provided one! Even if it’s completely irrelevant to the circumstances of the accident.

Oni Nou has an "unconventional" sense of humour. I think he's amused by the thought of helmets being scrutineered at a trial, because it is so unlikely.

As I understand it (leaving myself a get-out there), hydrogen embrittlement can occur when chrome plating, but is not inevitable. Nonetheless, I would opt for nickel rather than chromium, just to be on the safe side. However, if you're buying a 30+ year-old bike and there are no cracks in the frame, I wouldn't be too worried.

Nothing to do with fwd. Mercedes just seem to have a liking for big castor angles. True of C Class, E Class, maybe others.

Again Im comparing Mercedes car with Mercedes van, which may or may not be relevant. My C Class has an extreme castor angle so it knocks out the shoulders of the front tyres.

I don't know if its the same engine, but i have a direct injection petrol in my Mercedes car (1.6, turbo, intercooled, about 150bhp). It's not the most refined engine in the world when revved, but it's very nice when driven smoothly and gives diesel-like fuel consumption.

Who needs stickers when you've got sexy blue wheel rims? The letter J is pronounced "jota" in Spanish (like we would say "jay") so Jotagas and JGAS are exactly the same thing.

You can get a bike in a Kangoo: I've seen it done. I would guess the Doblo would work too because it's the same platform as the Citroen Berlingo that I use. No idea about the Vauxhall. I'll certainly give a vote for the Berlingo (car, not van) though you have to accept that it's French, with all that that implies.

That is a brilliant initiative. Any idea how many users of club bikes have gone on to buy their own?

Yes, the piston marking on the crown matches the squish area. Its hard to tell from the photos if that marking is due to debris getting smashed between the piston and head, or bad detonation occurring in there. If you only ran the engine without oil for a short while, that may not be the cause of the problem and is just serving to confuse us. I certainly don't think the ring area of the piston looks healthy. On the other hand there doesn't seem much wrong with the bore in the photo, but I think it needs to be inspected carefully and measured.

The following is supposedly an actual question given on a University of Washington chemistry mid-term exam paper. The answer by one student was so "profound" that the professor shared it with colleagues, via the Internet, which is, of course, why we now have the pleasure of enjoying it. Bonus Question: Is Hell exothermic (gives off heat) or endothermic (absorbs heat)? Most of the students wrote proofs of their beliefs using Boyle's Law (Gas cools when it expands and heats when it is compressed) or some variant. One student, however, wrote the following: First, we need to know how the mass of Hell is changing in time. So we need to know the rate at which souls are moving into Hell and the rate at which they are leaving. I think that we can safely assume that once a soul gets to Hell, it will not leave. Therefore, no souls are leaving. As for how many souls are entering Hell, let's look at the different religions that exist in the world today. Most of these religions state that if you are not a member of their religion, you will go to Hell. Since there is more than one of these religions and since people do not belong to more than one religion, we can project that all souls go to Hell. With birth and death rates as they are, we can expect the number of souls in Hell to increase exponentially. Now, we look at the rate of change of the volume in Hell because Boyle's Law states that in order for the temperature and pressure in Hell to stay the same, the volume of Hell has to expand proportionately as souls are added. This gives two possibilities: 1. If Hell is expanding at a slower rate than the rate at which souls enter Hell, then the temperature and pressure in Hell will increase until all Hell breaks loose. 2. If Hell is expanding at a rate faster than the increase of souls in Hell, then the temperature and pressure will drop until Hell freezes over. So which is it? If we accept the postulate given to me by Teresa during my Freshman year that, "It will be a cold day in Hell before I sleep with you", and take into account the fact that I slept with her last night, then number 2 must be true, and thus I am sure that Hell is exothermic and has already frozen over. The corollary of this theory is that since Hell has frozen over, it follows that it is not accepting any more souls and is therefore, extinct...leaving only Heaven, thereby proving the existence of a divine being which explains why, last night, Teresa kept shouting "Oh my God."

That nice quick closure is a big step forward, but I still can't help feeling the engine is not responding properly. Blipping the throttle like that should have the motor leaping up to max revs instantaneously.

Sorry for a bit of thread drift, but I don't understand this thing about tiller effect due to the position/angle of the handlebar clamps. It seems to me the only points of interest are the steering axis and the position of the handlebar grips. Everything in between is irrelevant. Isn't it?

Those kids bouncing around on bikes and scooters should be the next generation of trials riders (and motocross, enduro and circuit racing). Clubs and governing bodies are really missing a major trick if they let them slip through their fingers. I've done extracurricular talks at primary schools (about coastal safety, not motorbikes) and the interest and enthusiasm is awesome. It just needs channelling.

You can practice basic skills almost anywhere. Do tight figures-of-eight. Lay out a line of markers as a slalom and keep moving them closer. Put down a small obstacle and practice hopping the front wheel over it. Then add in something before and after so you have to turn tightly onto it and after it.When you go to practice on some proper trials terrain, try to have someone with you. You're more likely to push yourself if there's someone to pick the bike off you when it all goes wrong.

Isn't it a lovely feeling when it finally happens?