jse

I just heard of someone mentioning three rings on the 250 piston. 250's are really rare here in the U.S. (in spite of the fact they are great bikes) and the 280 and 300's have two "regular" rings and I haven't been in a 250 as yet. Some of the pre-Pro's used "Dykes" top rings which are "L" shaped in profile and you can tell if your piston takes a top Dykes ring by the way the very top ring land is machined in more to make allowance for the thickness the outside of the ring. If you, in fact, have two regular type rings a couple of things to remember is to install the ring with the writing on the top and measure ring end gap by using the piston to push the free ring about 15mm down the bore and use a feeler gauge to check the gap. Ring end gap should be .1mm per inch of cylinder bore diameter. Jon

You should expect the fan to come on fairly quickly on a hot day and the hotter it is, the more the fan will come on. At the low speeds we operate our bikes, the fan is necessary to draw air through the radiator to regulate heat in the engine. If the fan comes on at very first start, there is a good possibility that the thermocouple ("thermostat") switch is stuck and probably should be replaced. You can check the switch with a pan of water on the stove, a thermometer and a continuity meter if you want to see what temperature the switch makes contact. Keep the switch off the bottom of the pan (otherwise the switch temp, touching the bottom, will be hotter than the ambient water temp reading on the thermometer) and gradually allow the temperature to rise until the meter indicates a closed circuit. Jon

You could, but it would require some modifications and additions ( I converted a KX carb years ago for my JTR370). The PWK28 was on the KX80 at one time but the problem is that the adjustments are on the wrong side for the GG so everything (idle screw, air screw) would have to be re-drilled and tapped as they are on the right side and face the muffler (and the standard KX jetting is all off for the 280). You'll need the larger manifold, which came on the 96' JTR370 as that bike used a large body Dellorto with a larger spigot and using a standard 26mm PHBL manifold risks splitting it. The cable will need to fit the Keihin (it has a shorter casing) and there are a few other things, like a wedge spacer for the reed cage to keep the Keihin floatbowl off the engine casing etc. Your local dealer should be familiar with the conversion and could get the parts for you, I would imagine. Keihin makes the "special" PWK for GasGas for the Raga and as an aftermarket conversion with all the adjustments on the "correct" side (the carb body has castings on both sides for adjustments). Jon

I have the 02' Pro (actually an 04' airbox with 02' graphics) and the 02' boot which is smaller and only fits the Dellorto. The change to the wider boot in 03' was to accomidate the VHST Dellorto flatslide (only used in 03') and the Raga's Keihin PWK28, hense the donut adapter. The problem seems to lie in the fact that the VHST and PWK are slightly longer bodies so they designed the boot more to accomidate them, rather than the 26 Dellorto that most of us use. Next time you have the airbox off, take a Dremel tool and radius the front intake of the boot so without the sharp edge, the bell will slide in a lot easier rather than catching on the sharp angle. Jon

I haven't been able to find the recommended pressure for the Raga Ohlins shock (I'm assuming it is generally the same as the 36DR Ohlins) but based on past experience, I use about 140-145 PSI, which is what I run in a special remote reservoir shock I built for my 85' TY. Generally Nitrogen pressures are in the neighborhood of: Motocross-150 PSI Roadrace- under 400 lb spring, 200 PSI and under 600 lb spring, 250 PSI You can vary the pressure but I probably would not go lower than 120 PSI. The seal relies on pressure to work correctly and the Nitrogen pressure acts as a secondary spring in a way. The pressure helps to prevent cavitation at the damping shim stack and piston orifices at high shaft speeds. As I say, this is only a guess. Jon

And thanks again for doing it! To my knowlwdge, there are no shop manuals available for the GasGas Trials models, which is why Dale Malasek (US bike importer) and Jim Snell (US parts importer) got together in the mid 90's to make the Owners Video manual and updated them each year. Jon

I also think they are the 360 forks like the BMX guys use. Is this the same Freddie Crosset that was the 2002 NATC Pro Champ here in the US, or maybe his son? Jon

As I remember, the 05' has the dual ignition maps but not the switch (at least the 280's). There are two wires coming out of the module, a black one and an orange one. Plugged together will give you the slow mapping and pulled apart will give you the faster curve. You can add the 06' switch to do it from the handlebars. Jon

Just a note of congratulation. Just got back from California and I opened up my new issue of on-line Cycle News and there, in living color, is a nice, big photo of our own Jay Lael. A superb ride in the Modern Classic Expert Class at the Northwest Regional AHRMA Trials Series held at Crooked River Ranch in Oregon got him first place. Nice job, Jay! Jon

My first guess is a malfunctioning inner head o-ring allowing combustion gases to enter the the coolant passages. The thermocouple (it's a sensor switch and does not restrict coolant flow) rarely konks out so soon, but you can check it with a continuity meter and some hot water. Jon

I'm trying to remember but I think taking out the mounting screws allows enough movement of the radiator, when the hoses are taken off. If there is still a problem, take out the front and bottom engine mount bolts and the engine will pivot up by the swingarm mount. Jan, Probably the best way to break in a new cylinder is to ride easy sections. The on/off throttle applications will help keep the motor cool. There will be a little blow-by past the rings until they mate with the cylinder wall but if you avoid overheating the engine you'll be in good shape. 1.5 or 2% will work. I run a 70:1 ratio in my engines (50:1 in my air cooled TY) and had never had any lubrication problems with a full-synthetic premix oil. Jon

Hi again, Ed! I'm posting this from my hotel room in sunny Silicon Valley in Northern California where gas is over a buck a gallon higher than where I live (and still cheaper than a lot of places overseas). Those spec.'s should work for the 05' also as far as I can figure. The reason Dave was asked what gasket he had was that the thickness of the base gasket "set' is what determines the squish clearance when hand assembled at the factory. Dave, measure the thickness of the old base gasket set (it usually is more than one) and then add, say, .1mm for compression and order the number of gaskets that add up to that measurement. I think they come in .3, .8, and 1.0mm sizes so you will "mix and match" them to get close (over the measurement is better than under) and that should work Cheers. Jon

When pushing in the piston, it's quite easy to catch the outer lip on the outer radius of the bore. I usually drop the piston in until the seal lip rests on the beginning of the bore and then use the end of a thin sharp pick inserted carefully between the seal and the bore and move it around slowly to ease the outer lip into the top of the bore, using very little pressure on the piston. If you're uncomfortable using a pick, use a thin piece of 35mm negative strip (hard to find in the digital age now) or if the piston/bore clearance allows, use a strip of the negative film around the piston (don't overlap the ends of the strip) like you would use a piston ring compressor. The seal lips are sometimes flared out so that they seal better with added pressure on the inside but most are like a band, either way, the inner lip condition is critical. Jon

The dictionary defines "cope' as: "to struggle, especially on fairly even terms or with some degree of success". We're behind you all the way, buddy, that new medication is doing wonders! Jon..........

Sometimes the alignment makes it hard for the special mid-muffler o-rings (D shaped) to do their job. I always use some hi-temp Silicone sealer on the header pipe before sliding it in and then wipe away the excess, leaving a neat radius of it to seal the pipe/mid-muffler junction and let it cure overnight. When using Silicone sealer, always make sure the surfaces are clean. Jon

Peter is right. The 02' differs in that it uses two o-rings rather than an o-ring and seal on the servo cylinder tower and the 02' case is made from Magnesium. The later aluminum ones (03' on up) have reinforcing ribs cast into the inside. Since you will have it apart, it would be a good idea to flush the system and change over to DOT-5 (Silicone) which is compatable with all seals and will give a smoother pull at the lever (up to 20%). Jon

Unless you truely value the sound of large rocks being thrown by other riders (and spectators) bouncing off your helmet due to the extra noise from your exhaust, I'd have a good welder patch it, re-pack the muffler and re-install it. With the fasteners loose, pull the muffler out a little and then tighten the fasteners. I'm guessing you've fallen over on that side and the muffler bracket may have been bent, but it's usually easily bent back. Keep an eye on it and pull it out if you see rub marks in the future. Dirt acts as a "dry" rubbing compound where the tire rubs so it can be worn through quite quickly. The shortened muffler will affect power to some degree, with less low-RPM grunt the likely possibility. Cheers. Jon

Excellent, and nice detail work from what I can see. I look forward to Swooshdave's photos of you putting it through it's paces. Jon ps. I hope JandMHomes doesn't read the Forum and find you've been scarbing off with their signs. Course, in the present housing market, that's probably a much, much better use for it.....

Geeeeez. I think I actually agree with Copey (image of Jon, upon fully realizing the import of the last statement, one hand to forehead, other hand clutching chest, gasping for air and staggering around in circle and falling face first on office floor). As an addition to this jetting stuff I might also add, always check your plug when making jetting changes or now and then just to see how things are going on inside your engine. The plug is probably your best, direct link to what's happening in the combustion chamber. Once you understand the "language" the plug speaks (color, deposits etc.) it can give you a great deal of information and help keep your engine healthy. For instance, I used to tell how much fuel a nitro burning Top Fueler needed, in part, by counting how many threads on the new plugs turned blue from combustion heat after a tune-up run. Jon

I wouldn't worry. The bike runs well and the #60 jet you saw was probably the "starter jet", which is on the end of the brass tube with an o-ring on it and only used when the "choke" lever is up. Jon

Max, Probably the best thing to do is re-set the mixture screw and if that doesn't solve your problem, take the carb apart and make a list of all the jet sizes and other settings and let us know. If you don't know where you are, you won't know which direction to take. The smaller the engine, the more critical the jetting is. There are a lot of things that can affect the off-idle response, those mentioned, as well as slide cutaway, needle profile, needle jet size, float setting, type of fuel etc. You might be having trouble with the mixture screw, but the cause may be something else altogether and unless you can eliminate the other factors, you may be treating the wrong symptom. Chances are you are o.k. in the jetting department (in the range of #36/38 pilot and D-34/35 needle) and if you bought the bike new it should be good, but if it's a used bike, previous owners can be pretty creative in what they put in the carb from what I've found. Jon

Ralphy, It might be a good idea to take the shock to someone who knows suspension and have them check it out if you're not sure. I haven't been into the Beta Paioli specifically, but most new shocks have a floating piston that seperates the oil from the high-pressure Nitrogen (monotube DeCarbon type), rather than the old low-pressure Nitrogen emulsion shocks. Jon

And if ANYBODY knows about creeping and dragging, Copey does....... Use a piece of glass, carefully, (or a $30,00 granite surface plate...) and lay the steel plate on it, then try to slide a feeler gauge, say .003", in from the side at various degrees around the plate to check it for warp. Sometimes just looking at it from the side will show if the plate is not flat on the glass surface. Jon

The "best" setting on a mixture screw will vary from carb to carb and engine to engine, and also be dependent on ambient weather conditions (temperature, humidity, barometric pressure). Probably the "best" way to set it for your engine is to warm up the engine and, from idle, quickly blip the throttle (turn on/off rapidly) and adjust the screw to give the best throttle response. You can also try turning the screw 1/4 to 1/2 turn richer after getting the best response and sometimes that will give the best performance, but I've usually found that the Dellorto works well at the "blip/best response" setting without going a little richer. Jon