jse

Haven't got a clue, Wayne, but I agree you should check it out. The on/off nature of the clunk is disconcerting and asymptomatic noises are the hardest to diagnose. Jon

See Al? Ya learn something every day Actually, they tried the tubeless front tire, on some of the Fantic's, possibly the 309 model as I remember. It didn't work very well and in a muddy, wet Trial you were fairly well assured of the tire slipping completely off the rim. My guess is that the twisting of the tire casing caused by normal steering changes worked water in between the tire bead and rim, which then acted as a lubricant to allow the tire to roll off the rim. Jon

The leaking around the valve is probably due to the washer/band on the backside not sealing. You could try tightening it but that depends on how lucky you feel. I'd take the tire off and find out what the problem is. If the back tire leaks on a regular basis, you will not enjoy riding the bike. There is not much pressure in the back tire so if it's leaking, so I'm guessing it's a mechanical problem with the washer/rim band. You may not need to replace the band if it's in fair shape. I like to store my bike with 30 psi in the tires as I think it helps to force moisture out of the bead area and keeps the band tight against the rim. I've not had a leakage problem in 9 years. On the front tire, the leakage from the rim lock is the secondary problem and leakage from the tube is the primary issue. You (if it's a new tube) probably pinched the tube putting it in. When levering the tire bead on the rim, if you go past vertical with the tire lever you stand a very good chance of pinching the tube against the inside of the rim. Take shorter "bites" of the tire bead to lever it on and push on the bead (the part that is already inside the rim) to roll it on the rim rather than just lever pressure. Unless you never use your front brake, you will not need a front rim lock (just kidding, yes, you need the rim lock). Jon

The pressure plate does not move much and 4mm sounds close to the mark. You might want to pull the pressure plate off and check all the plates, both for condition and being straight. One of the fiber plates may have the pads coming off (believed to be possibly caused by other-than-recommended oil and moisture reacting and creating an acid condition that attacks the adhesive holds the pads to the steel plate). Jon

Most of the riders use Dexron for the models up to 06' and Type-F for the 06' on up models. Good, light-viscosity motorcycle specific transmission fluids also work well in most cases. ATF is around 7.5 weight and "75 weight" transmission fluid is roughly equal to a "10 weight" motor oil (transmission fluid is viscosity-measured at a higher temperature than motor oil). Jon

I have an 02' Pro 280 and with minor updates (clutch pack and air box) it has been ultra reliable for the 9 years I've riden it. I could easily have a new bike each year but I really like the 02' and still have fun riding it (and it's never let me down). The 02' has the non-anodized Magnesium engine so you can ride it hard but you can't put it away wet, literally. Check behind the flywheel area and under the engine for signs of corrosion. The handling of the 02' is a little better than the later models from my experience but all-in-all, it's a good bike and will give good service if taken care of (like any other Trials bike). Jon

I think it depends on what result you want. I run a modified Mikuni flatslide on my TY350 (see photo) but when I had a Sherpa-T 350 I was quite satisfied with the Amal 900 concentric, even though a lot of my friends converted to Mikuni's. I think you need to decide what the engine is not doing for you rather than what other riders are using and that decision will dictate your modifications, if any. Jon

I agree, the conditions under which a Trials gearbox/clutch operate and an automatic transmission operates are very similar. Atf is made for a wet-clutch environment, has good shear strength and lubricity and has anti-foaming additives. We used to use a pint of it in our Top/Fuel dragster differentials as an additive. The key is to change it often to keep it fresh. Jon

Jeeez, I only wish my fork oil level was the only reason I get so many fives.... Jon

I generally find the spacer works well when it pulls the reed cage back a little to unblock the side intake ports in the intake tract in certain engines (incidently, those "feeder" subports are called "Boyesen Ports" after the guy who developed them). There are some cases where a spacer works to move the carb up a little where an aftermarket carb bowl hits the top of the engine cases (it prevents "fuel frothing" due to harmonic resonance). GasGas has a neat spacer that is wedge shaped and moves the carb (Keihin in this case) up off the case more than if just a standard spacer would be used. It's a new take on an old trick we used to use in the "old days" to adjust carb levels when adding different carbs to our racing engines. Jon

Guy, You'll probably find the engine performs smoother with a little more torque output. The phenolic resin reeds are more pressure responsive than steel and the dual-stage design (a combination of two different sizes, thickness and shapes of reeds) allows better flow throughout the RPM range. Jon

Al, Actually fork "oil level" is measured in a different way than what it sounds like and it's easily mistaken as to how the proceedure is undertaken. Due to the different internal construction of the Marzocchi forks, as opposed to the earlier GasGas forks that are usually easily set by volume, the "Zokes" are more difficult to drain the cartridges completely. When they first came out riders were having a problem with overfilling them after servicing even though it seemed like all the fluid was removed from the assembly. If you want to be accurate when servicing/adjusting forks you will always use oil level rather than fluid volume (all good suspension shops will always use oil level instead of volume when there is a choice). Adjusting that "air gap" (the 180mm for steel tube and 160mm for aluminum tube on the Marzocchi's for instance) measurement is also one of the ways you can change the way your forks perform. The air gap, of course, can be adjusted to plus or minus the standard measurement to a degree and the gap affects the last third of fork travel. Say, for instance, you are having a problem with the fork bottoming out on big drop-offs and you don't want to change the oil viscosity to a "thicker" oil because that would affect the damping across the board, especially in the first/mid stroke of the fork, which you are happy with (and the thicker fluid would make the fork less reponsive to smaller obstacles). You could decrease the oil level measurement from say 180mm to 170mm, which would leave a smaller "air gap" at the top of the tube when the fork is fully compressed. That "air gap" acts as a secondary spring and like coil springs, when you shorten them, you make them stiffer (increase the "spring rate".) This way you can target the fork problem area (bottoming out) you want to perform differently without affecting the other areas (overall damping) you want to stay the same. The standard proceedure for measuring oil level is: spring removed, cartridge completely free of air and the top tube fully collapsed into the lower leg. The measurement is taken from the rim of the top tube down inside the tube to the level of the oil with the fork tube straight upright. Jon

I'd replace the steel reeds with a set of Boyesen dual-stage reeds to start. The spacer can do several things: (1)reduce the primary compression ratio, which tends to reduce low-RPM torque (2) increase the length of the intake tract which tends to increase the low-RPM response and (3) unschroud the intake boost ports in certain cases, which tends to increase cylinder filling at all RPM's. The thickness of the spacer will depend on several factors (they usually run in the 5-10mm range) but I think you'll get a lot more bang-for-the-buck by replacing the steel reeds with the Boyesens and then experiment with the spacer later. Chances are the old steel reeds may experience fatigue at some point and the results of an engine sucking a steel reed petal can be expensive. Jon

Marzocchi's really need to be set by oil level, not volume, unless they are totally dry. 160mm for the aluminum tube and 180mm for the steel tube types. Jon

Not an inteference fit, but possibly very "snug" all the same with any frozen condensation and thick oil entering into the process. Also bear in mind that a good deal of the contact surface in the cylinder/piston area is ceramic, in addition to metal. Nikasil being Silicon Carbide particles in a Nickel matrix and piston composition being about 14-22% Silicon Carbide in most cases. This may be part of the equation, although I'm not sure as I've had no reason to experiment. I'm sure it doesn't happen all the time, but a little warmth applied to the cylinder when starting at extreme low temps might be a good idea. I've run my bike at those temps without any problems (for the bike that is, not for my old body....). Jon

Not surprizing. Trials engines run really tight piston skirt/cylinder clearances, in the neighborhood of .0015"/.002". Another good reason why you, on "normal" weather days, should allow the cylinder to get warm before taking off and rev'ing the engine, it will reduce piston wear a huge amount over time. Jon

In my experience, the longer headpipe tends to favor torque production in the lower RPM range, rather than higher. The added length times the pressure/sonic pulses farther apart, which favors cylinder filling in the low/mid range rather than higher RPMs. The S-3 heads are a nice idea as you can change the secondary compression ratio without changing the port timing. Great for us flatlanders who want to ride in Kansas one week and then head up to Colorado for the Ute Cup and a simple change in chambers makes a huge difference. You have to be real careful with exhaust restriction in a two-stroke as you can run into overheating problems very quickly if you go too far and exact placement of the restrictor in the exhaust system is critical. The four-strokes are less prone to these issues. Jon

http://www.trialspartsusa.com/tech.html should cover all your needs. Not specific to 05' Raga but same spec.'s as 06'. Jon

My guess is that you might need a rebuild kit for the master cylinder. It may be that you have up to 10 years use on the M/C internals and normal wear is the cause of the drag. A broken rubber boot will allow fine grit into the M/C bore and cause accelerated wear of the piston seal. Jon

I'm assuming you mean the Allen capscrew down inside the clutch hub. That's a special capscrew that has been drilled to allow the transmission to "breathe" and has had the head cut down for clearance when the clutch servo cylinder drops down into the hub when the clutch lever is pulled (and should not be replaced with a standard capscrew as sometimes the servo cylinder "top hat" will bottom out against the extended head and the clutch lever will stop before hitting the grip). The previous owner probably used an old used Allen wrench to try to get it out and the worn flutes on the end of the wrench shaft quickly rounded out the capscrew as the center is shallow (due to being cut down) and there is reduced grip. You can first try a new 4mm Allen wrench or an old one with about 5mm cut off the end. If that does not work, try a T-27 Torx bit next. The T-27 will be a little larger than the capscrew hole and tapping the end of the extension it's on will help break the thread bond and force the Torx bit to cut down into the hole to allow grip to back the capscrew out. If you are in a bind and need to ride, you can leave the capscrew and stepped washer out (don't forget to also take out that thick, stepped washer in the center of the clutch hub!) and you might get a little more oil out the breather (so keep an eye on the oil level), but otherwise it should be o.k. till you get a replacement capscrew. The pressure of the spring-loaded servo cylinder will hold the clutch basket on the shaft. I know of several riders who take out the capscrew and washer as they say it makes it easier to remove the clutch, but I personally like to keep the capscrew/washer in the hub. You can also use the Torx to re-install the capscrew if you want but you probably want to replace it soon just to be sure. As mentioned, use a new or cut-down Allen to install the capscrew and I like to use a little blue ("servicable" type) Loctite on the threads. The new/cut-down Allen wrench tip also applies to the drain plugs on your bike which are aluminum and easily stripped out. Jon

Assuming you've got a little play before the adjustment screw on the lever starts to exert pressure on the plunger that goes through the rubber boot on the master cylinder, how far (measured at the lever ball-end) does the lever move before you feel good pressure? Also, is the rubber boot at the M/C in good shape or is it torn or falling off? Jon

I have a fairly extensive motorsports video collection (o.k., an obsession, with probably about 400+ just of Trials only and recently spent about 4 months of my spare time converting my old VHS's to DVD format) and the slow-motion portion at the end of Robert Walker's 97' World Round, with background music by Ray Lynch, Michael Hedges etc., is one of my favorites. I made a "shop DVD" to play in my shop while I'm messing up an engine, with my favorite parts of various Trials videos and I must have Robert's slow-motion 97' WTC segment on it a couple of times I like it so much. Jon

I don't like to go more than about 10 hours of use, especially in the Pro that has extra parts to lube. The operating conditions and environment in a Trials engine can be more severe and moisture/grit contamination is always a consideration in such a small volume enclosure. To take the issue to an illogical extreme, most automotive motor oil should be changed in 3-5000 miles, yet all 14 quarts in a T/F Dragster needs to be changed after 1320 feet. Jon

Go to: http://www.trialspartsusa.com/tech.html and click "Carb settings" and the spec.'s for the 01-05 70 will be there. Some 70's have a bog off-idle and I think the modification on the slide to correct it is also on the website. Jon