toomanybikes

Nice try with the unsprung weight argument. What doesn't make sence is you say the MX can benifit less unsprung weight, which is true. However the steel sanction of the fork is heaver then its aluminum counterpart. This puts the heavier steel sanction of the USD fork on the bike needing the less unsprung weight, the MX. Thinking, but I do not see where it make sence. Note their is not much difference in fork sanction weight anyway. Most of the forks unsprung wheight comes from the oil, the cartridge and the spring. It takes some skill to ride a MX at the level to tell the difference in rigidty between conventional and USD forks. But the difference is there. The USD is much more ridged!

That quote could be from any trials manufacturer. Take trials out and it could be from any motorcycle manufacturer. Take trials and motorcycle out .... I hope Sherco is hard at R & D because the boilerplate they make their press releses out of, ant so fresh.

I don't know. I too have asked this question to dozons of people. The most reasonable answer i have gotton so far is, "a skinny trials bike dose not look right with the fat part of the forks at the top." I know very lame, but that is the best and I have asked a lot of peaple that should know. I hypothisise the real reason is fork stiction. In the trials world it is common to intentionally hit obsticals with the front wheel; zap, splater, double blip. Not so in the moto-world or enduro world where you try like hell to avoid obsticals with the front. (I had a HUGE problem with this when I came to trials and still do to some extent). This intentional hitting aplifies the horizontal bending force on the front forks. The bending force is greatest just under the lower tripple clamp. Upside-down forks are more ridged in that area so the bending is moved down to where the upper sanction ends. In that area the fork bushing rides, bent shafts in bushings tend to bind. A little bit of friction can drastically effect the transfer of energy for manuvers like the zap or splater. Trials forks being thinner and lighter than moto forks this could be a real problem especially for hard hitting top riders. Mayby only a few of the top riders notice the difference, mayby more. I don't know. Mayby the 'looks' explination has more merrit.

The proposed rule changes were based on the machines meeting the emission standard, not if they were two stroke or four. The new HONTESA is fuel injected, if it was more practical to clean up the two stroke with fuel injection wouldn't they have done that. I keep seeing posts about x company developing clean running two cycle engines that beat the emission rules, where are the pictures and emission test results ? 05 should open a few eyes one way and another, Raga will be on (to some) the lightest and best two stroke ever built, and his closest competition will be on big fat slow four bangers. I have to disagree with you Ishy; The rules are all about getting rid of the 2-stroke, not cleaner emissions. Several manufactures have proven this. I know it is commonly believed that a four stroke is cleaner than a two, but this is not the case. If you go to the EPA's webside you will find tests for modern moto-bikes, outboards, and powerequipment and find this is not the case. As far as trials bikes, I doubt if anyone has ever tested them at all since they represent such a small portion of the market. Moto-bike tests should be close enuff to verfy what I am saying. The four stroke laws are just a way for the Nature Nazis to chip away at the logging and powersports industries. As a Sierra clubber mindlessly hikes through the forest, the first thing that disgusts him is the blight of the clear cut done by loggers with chainsaws. Walking through miles of clear cut can give anyone a bad attitude. Then after wasting your weekend walking through miles of clear cut just to enjoy a little bit of nature some bloke on a motorcycle flys by you and you relize that hes enjoyed much more of mother nature in much less time. This would be enough to p*** off even the wimpiest of Geeners off. Being a mindless boring activity, hiking provides the Nature Nazi lots of time to think. Think about how he can eliminate his nemisis, the loggers and the motorcycles. Dispite all the resources behind him and his buddies, (the Sierra Club and the like are multimillion dollar organazations with little or no product produced) he cannot confront the timber and powersports head on. So what weekness do they have in common: the two-stroke engine! True or not, (NOT!) it is common knowledge that the two stoke must be dirty. Get rid of the two stoke and you strike a blow against the logging AND powersports industy. Brilliant no?

I certainly could be wrong, but it appears to be a SOHC with two valves. Cam is centered on head unlike Unicam. You can see two distinct rocker arm shafts on the right side of the head.. The plug (boot) is angled. (although I would not be surprised if the plug hole was not drilled on this for show only model) On a four valve head the plug is usually centered. The rocker shafts appear rather short for a four valve head. Doubtful, but it could use a rather shorter forked rocker like the early XRs, TL 250s, or the more modern quads Don

I have been negative about this four stroke thing. But with all due respect, I don

I can

UniCam? Does not look like the CRF UniCam to me. Looks more like the Honda Helix head (http://www.motorcycle.com/mo/mchonda/helix.html). Appears to be a SOHC with maybe just two valves. No flat head. And note: Honda lawn mowers have not had Flat Heads for at least 20 Years. Current models even have SOHC. Maybe that is what that is? I am afraid that fuel injection is a little more complicated than my mate Ishy states. The sensors are rarely simple on and off switches. And more info is needed other than crank position and throttle position. A mass air flow or manifold air pressure or both is needed in all electronic fuel injection systems made to date. Engine and air temperature thermostats are also needed to complete the fuel map. A computer must be programed with the fuel map. I also am skeptical that a Capacitor is used to start the fuel pump. Fuel pumps, especially high pressure fuel injection pumps, need quite a bit of voltage and amperage to start. To which end, I think I spy a little battery behind the voltage regulator( also needed for fuel injection).

Me thinks Ian is right. Down spars appear totally machined, unlike a production bike. Engine cases and mag cover are sand cast, and poorly done at that. Painted also to cover up castings. Fenders are extremely glossy and what looks like a candy paint. No serial number one the left side engine case. Prototypes and test models are given numbers for data logging and testing purposes. Over a year before Honda produced the CRF250, they were pimping a model as such in the magazinens and at the bike shows. It had a plastic seat and a solid motor. Think we have the same here.

Look at Canondale! Their four stroke wishes put them under. The very profitable bicycle end the business was drained also. Lot larger margin in bicycles! I am sure GasGas has the largest margin and largest production of any of the trials manufactures but I don

Hey Beta-boy, are you dating HRC2002 sister?

My take on four strokes - The manufactures recommend that modern four strokes need the oil changed religiously every other or third ride. Oil filter or filters (the KTM has four) must be changed (or cleaned also). This can be a huge pain if you take into account the hassle of some of these dry sump or semi-dry sump systems or removing a hot four stroke pipe. Regardless if you change it or not, the fours may consume their lubricating oil. When endurance racing (say 50 miles or so), CRF owners often fit a additional oil tank since the bike will consume all of motor oil. Not exactly more environmental in any aspect. Ishy