marlintec

Hi all, After the first year of use, I think we have more clear the arguments of the new 4S machines. I own a 4RT with just one year old and I would highlight this points: - Flawless bike. No problems at all in this first year. The bike keeps intact its performance in one year. - Great response of engine, always constant in any situation. - A little bit heavy in front, difficult turning. I got more tired with the 4RT than with a 2S. - Great suspension. - Not cheap to do maintenance: so frequent oil changes, included oil filter, made the bike significantly more expensive to maintain than a 2S. The final point: Would I buy it again? Probably not. The main reason is that my riding level was clearly lowered with the 4RT. I have the 4RT yet, but I ride now a GG 250. Probably will sell the 4RT. I would like to know about other opinions, very interested in Sherco 4T users. What you think boys about your 3.2 after this first year? Cheers, JM.

Mecatecno's engine has rotative valve, so the piston skirt has no effect. You can effectively mill the barrel base to use sherpa's pistons. Be sure to let the squish clearance at least to 1.5 mm not less. The engine is suspended on the chassis, bolted in the head. So if you change the barrel height maybe you'll have a tight fit in the chassis, be careful. I owned one of these beatiful machines in the eighties. 'Dragonfly' was her name (had an iron sleeved barrel) the last model was 'Skywalker' (nikasil barrel). Cheers, JM.

Ah! one more thought: sorry for the evident, but... are you sure about the wire to ground for killing the engine? If you used other wire, may be you're killing the engine forcing the CDI o other unit, leading to a fail in one of these in few hours. Take a look at the wiring loom: the colour codes change in almost every plug I can hardly remember that the kill-wire come out the CDI as a two-colour code. Cheers, JM

Hi Jools, Maybe this is a long shot, but I found that the tank screw was too long and was scrapping on the CDI unit, making a nasty mark. Surely, if I had rode the bike in that condition, the screw could make some real damage. The CDI is only fixed with a very soft plate, allowing lot of movement and vibrations. I fitted a rubber block (silent-block) between the CDI and the screw of the HT coil to definetively fix the thing. Cheers, JM.

I remember the mag wheel oiled in those 1999 Bultacos... Well, it's a way to avoid rusting on coils ;-). Sherco has a very dynamic crew in trials and will get all these little things sorted. The carb item is the major problem, I think, and in some places, the hot running. About the head torque, my 32-33 Nm were a guess based on the type of stud and kind of work. I see that the recommended tightness is about 10% less than my guess, so may be the big barrel needs a margin for dilatation. By the way, Bikespace is right: 3 kgm / 0.102 = 29.4 Nm x 8.85 = 260 lbsin. What I like very much of Sherco is that the 2stroke models are maintained on production. I have some doubt that the future of trials passes through 4strokes. It has been shown that 4S machines are suitable for some rides, whereas others do not enjoy the new engines. Sherco increases the ''bio-diversity'' of trials instead of reduce the possibilities, that's good! I wonder if Scorpa will do the same or, like Honda, will bin the 2S bike... Hope they don't. Yamaha still produces very good 2S MX's. Cheers, JM.

Ishy, I would ask to Paxau or directly to information@sherco-moto.com (Andreu). I think is a 8 mm stud of high tension steel, so the nut should be tight to 32-33 Nm for the head. As comparison, Honda 4RT uses 9 mm studs that must be tighten to 39 Nm. To convert Nm to inch-pound just multiply x 8.85 ( to convert Nm to foot-pound multiply x 0.738) ( to convert Nm to kgm multiply x 0.102) I'll post the information if I get before you. Cheers, JM.

It's a pity that Sherco doesn't care about manuals or handbooks. When I bought the 2.5 '04 I did received absolutely nothing; I understand now. My handbook-poster was to be given with the '05 bikes... On the other hand, there is a lot of information, tips, etc. on their web, developed by the US importer I think. But in this case, is evident that the bike arrived too soon or the instructions too late. Soon or later, your dealer must do some work to the bike and I wonder if he knows how to. Surely he do. The first valve-check is after 5 hours... Maybe other Sherco4T could tell us about. In anycase, I'm surprised to see the change in the chassis... Anyone has more information? Cheers, JM.

Uh, really tight, it's true The prototype I tried had enough play to lift a little and save the 'plug tunnel' edge (it is an independent tube and remains free between head and cover). Maybe they have changed the chassis in the final series? Look at this photo of the early prototypes... What says your dealer? Have you any manuals?

It's weird to me. Did you try yet? The top cover has a 'T' rubber gasket and, after unbolt, has some side play, I think enough to wiggle a little and quit. Have you ask to your dealer? Cheers, JM.

RE500, it's very very easy. Just remove tank and unscrew the two bolts of the cover (it cuold be good also to untight the bolts of the triangular cover that support the cam bearing). The cover will 'undercover' the rockers and you will a lot of space to check clearances. Much better than in Cota 4RT, that needs to remove fuel tank and injector, four bolts (for 2 covers) and there isn't so much space to check clearances in exhaust valves. Anyway, Sherco 4T uses the vase/shim system, so may be you'll need a set of shims to do the adjustement. Cota 4RT use the old bolt/screw system... but you'll need a special wrenck to hold the screw (a little squared head). If adjustemt is needed, remove the triangular cover of bearing cam and extract the rocker axes through the cam-wheel (very easy), then you can put o remove the shims. In a talk with Josep Paxau, he said that after the first adjustement, valve clearances endured for long long time. Anycase, it's a job for your dealer to keep the bike on warranty. Cheers, JM.

Decompressor is centrifugal: when cam turns below certain rpm (I could remember about 600-800 rpm) a spring keeps pushing a lobe that lifts the exhaust valves (just a little fraction of mm). Just the minimum to allow you kick and also the maximum to allow the engine start without so much loss of compression. When you kick and engine starts, revs go up and a little weight, centrifugally moved, retracts the spring, leaving the lobe free and valves close completly. Honda 4RT works similarly. Sorry for this verbose explanation, its much better to see it (just quit the head cap). About the 30 hours... It's not the same 30 hours of a hard spanish summer trials than 30 hours of greenlanning on Yorkshire woods. Figure yourself the effort realised and act in consequence. 30 hours should be the maximum delay, in any case. Ipone R4000 isn't a cheap oil and I would search for an equivalent, cheaper, that allow more frequent changes. I would prefer separate oils, one for clutch-gearbox and other for engine (like 4RT), but Sherco uses the same 2stroke crankcases and, if oils were separate, mere 300 cc would rest for the engine. Insuficcient, clearly. Maybe in the future we'll see a new flywheel case to allow a truly oil pump and a little more oil... Cheers, JM.

800 cc 10W50, at least in the prototype pre-series I could try last year, I think the final series also carry the same. I was told that Ipone has developed a special oil for this kind of work. I'm confident that the improved quality of oils on these last 20 years could be enough for the Sherco 4T requirements. As comparison, Honda 4RT carry only 450 cc of engine oil (+ 550 cc on clutch-gearbox) but, in this case, there is a very efficient oil pump. Cheers, JM.

There isn't a mechanical oil pump, lubrication is by oil splash and oil circulation by crankcase pressure pulses. Yes, like early Husaberg/Husqvarna engines. Oil is shared among clutch, gearbox and engine, and filtered through a metalic mesh. This two features concerned me a little about mechanical reliability, but they may work in a less stressed trials engine better than in a high revved enduro or MX engine. We'll see this year. Cheers, JM.

Lots of interesting numbers, thanks. Gasoline should remain as fresh as possible, as well as air intake. Peaks of 40

Thanks for the photo, RE500. The system is definetively different in your carb. Mine (VHST26BS, year 2003) has the same set than in PHBL. Maybe Dell'Orto has changed the set to avoid the old problem. About the heat, it seems not so high for electrics (did you measure the HT coil temp?) Do you have any measurement of the oil temperature? (the stator runs on oil bath) The aluminium muffle radiates lots of heat around, I even know of a bike that got the 'seat' (mudguard) melted. The insolation like Ishy says could be the key for these problems. Cheers, JM.

Sorry, RE500, I don't exactly understand what you mean with ''spring on top''. The top (tip) of this needle is covered with rubber, and the body has a tiny spring within (you cannot see it) that pushes out the T shaped part. Seems that a change on the stamping machinery of Dell'Orto has produced some defective units that were mounted on VHST carbs. You can easily found this needle on any bikeshop, but make sure that is of the same lenght and size. Also, I'd like to know your temperature tests! Ishy, I think there are people that testing the insulation sheets between head and carb, as you note. I don't know if the problem with ignition is on the HT coil or in the mag coils. The bike I referred before was changed all the electrics, and I don't have more news on which was the faulty part.

RE500 your reading is right. The rich-lean-rich-lean-lean-rich-rich-lean... with no apparent reason is the symptom of a fail in the fuel input to the carb. This could be a clogged line, a non-vented tank, a small floatneedle jet or as in this case, an erratical float level. You may check your float needle and ask to a friend to borrow his PHBL set. it's just a straight swap, yes. BUT... in your bike there is one more thing to check: the heating of carb. A very warm carb also gives the rich-lean-rich-lean-lean-rich-rich-lean... symptom. It may not be a problem in UK... or do it? In relation to this, I remember the same problem in the bike of Eddy Lejeune when he changed from the old 360 to the new RTL engine. After all these years, when Honda bets for fuel injection in a trials (it could be done before in any CRF or CRX)... it is also a 'symptom' to bear in mind. Cheers, JM.

They aren't exactly the same. Both are Dell'Orto, but 2stroke bikes use the wellknown PHBL26BS and the new 3.2 4T uses the relatively new VHST28BS (flat slide, bigger bore, emulsion-type pilot jet). This VHST carb series seems to have some problems with the float level, caused by the needle-float set. These problems are erratical, so may be present in a bike an not in other. (You could read more on this in http://www.terra.es/personal9/marlintec/taller , in the VHST section, chapter VI, in Spanish) Furthermore, I know that some tests with Keihin carbs are being developed in the 3.2 4T nowadays. In relation to the SSDT problems, seems to be addressed to the ignition system. A bike also developed the problem in Spain (not much rain) so it seems not to be a problem of wet, but heat on the coils. I'm very confident that in Sherco will soon resolve these problems and we'll have a serious alternative to the 4RT. Cheers, JM.

The information is true. I wonder what could be the problem and if all or only some units are affected. Do you know the problem, Trialero13? JM

Montesa-Honda halt production of 4RT and command dealers to stop selling units. Dealers in Spain received on thursday the order to stop selling 4RT. The communication relates also that the production of units has been halted. It does not explain the reason but insist to remember to all clients on the obligated starting with throttle completly closed and waiting two minutes at idle before going. In few days they will communicate the countermeasures. As a 4RT owner I feel quite worry about this. I know that the delay of october was due to a change in the kickstarter (it touched on chassis and was re-molded), but this new seems to be more important. I do not imagine what could be the problem because I have had only eight excellent hours on the bike. JM.

Yes, it's loud. I own also a TLR200 and owned a XLX, the sound of the new Cota is definitively louder than desired. We are working with sleeves to reduce the backing noise (when throttle is closed). Here is a prototype that worked good with sound (but it restricts the top rpm). Cheers, JM.

Sure! I've not much time to spend, and maybe I should wait to my pensioner (pensionist? retirement?) in 2035 but I will finish it. Cheers and many thanks for your interest! JM.

Here you'll find al info about (in Spanish) http://www.terra.es/personal9/marlintec/taller Cheers, JM.

They sell the set cylinder, piston and head. Same stroke, new bore (79 mm, same as GasGas 300). You may call to get more info. Very professional shop. Cheers, JM.