jse

As the old geezer in the bunch, I'll throw in an old mechanic's trick from the 50-60's, although I doubt it would work as well in the high-tech engines of today. I was working as an apprentice mechanic to support my scholastic life at the University and a very old mechanic taught me this one, which at the time worked very well. He would take a pint jar and fill it with a 50/50 mix of water and old brake fluid, dribble it down the carb at moderate RPMs carefully so as to not kill the engine, dump the last part of it to stop the engine and wait about an hour. Start it up, kill all insect life within a mile radius and voila!, carbon gone with the bugs. The old engines were fun to play with but prone to carbon problems, in part due to the primitive fuel systems. Course, the good thing at the time is that was that Chevron had 102 octane Supreme at the pumps for 25 cents..... Jon

Might be the o-ring/seal, especially if the rubber boot is broken, which will allow fine grit to get in (grit+brake fluid=grinding compound). Check to be sure there is a little slack where the rod meets the piston (up inside the boot and it's the same for clutch and front brakes). I've seen riders tighten up that rod too much (trying to change the brake lever height) and the bleed hole is blocked off when the piston does not return fully to it's stop at the circlip. The brake will get worse as time goes on as the fluid can't enter the master cylinder to equalize the system. Sometimes the fitting at the master cylinder will get loose as the crush washers compress under flexing so you might check that also. Jon

You can use from 280-300cc's of 5 weight in each side. I've found they work fairly well with the rebound fully in and compression fully out, but it's a personal thing and can be dependent on who serviced them last. They may have messed up the adjustment needle by putting the top cap on too tight to the damping rod that goes down into the cartridge, which will sometimes cause a ring depression to form on the needle tip where it contacts the orifice and makes the needle essentially useless as a damping adjustment. If I take the cap off the damper rod, in order to re-install it, I'll screw the adjustment screw/knob all the way in, back down the jam nut a little on the rod, screw the top cap on till it lightly bottoms, lightly snug the jam nut up to lock the cap on, back off the adjustment screw/knob all the way, tighten the jam nut against the cap and then set the adjustment to where it should be. Assuming the tubes are straight and the lower legs haven't taken a big rock hit, fork stiffness is usually binding of the components caused by improper tightening sequence. Start with the upper clamp bolts tight (25Nm or about 18 ft lbs) and all other bolts loose and the brace off. Push on the forks up and down to "center" them and then tighten the lower clamp bolts (25Nm, 18 ft lbs). "Center" the forks again and then tighten the axle clamp (12Nm or about 9 ft lbs). Center again and then put the fender brace on the forks. If the four capscrews don't line up exactly, don't force them in as this will mis-align the tubes. Use a rat tail file to elongate the holes a little to get a proper fit. Cheers. Jon

Simon, I'm not quite sure as to the "appropriate" premix ratio for a 50 as I checked my files on the GG 50's and, for instance, the 06' TXT Boy50 model owner's manual recommends a "1.5%" ratio, yet the 08' Cadet50 owner's manual recommends a "2.5%" ratio. I know that, generally speaking, the smaller the engine in the higher RPM sports, the more oil is needed (up to a point) in the premix for adequate lubrication as they can run hotter and have localized "hot spots". So 80:1 is a lean mixture for the 50, but I know a lot of riders who run that in their kid's 50's without any problems. As the engine is new, you might want to error on the side of being a little rich and after some ring break-in time the oiling problem might be reduced and I'd re-seal the exhaust joint with some hi-temp Silicone sealer in the meantime. Jon

He and his wife are heavy into dual-sport riding and taking a break from the Trials scene (he was mentioned in the last issue of "Ride Oklahoma" magazine in one of the articles). I told Chris that he'd be back some time and we'll welcome him with open arms. When I came back into Trials in the 80's after a short break, a old Trials friend told me: "Whaaaal, Jon ole buddy, it's nice to see ya back. I done tole ya that riding Trials is kinda like smoking ceegars and riding Ducati's.....ya may giv'em up for a while, but sooner or later, you'll always be back......" Jon

He came out to California to ride a National we put on and was even more impressive in person. Great guy to talk to. Jon

The flywheel fastener goes to 40Nm, or about 29.5 Ft lbs. Don't lap the flywheel unless there is severe damage to the tapered shaft and flywheel hub and it's a last resort before replacing the crank and flywheel. The Woodriff key does not hold the flywheel tight to the hub and is only used for alignment during installation. What holds the hub to the crank is that the tapers of the two parts are not a perfect fit. One taper is bored/machined at a 1 degree +- angle of the other one and it's known as a "one degree interference fit" or more accurately a "Morse Taper". Jon

Hey, Dan! And it was a "2001 TXT Pro", an extremely rare bike! Cheers. Jon

I haven't seen them do this much on this side of the pond, but I bet if he took up the slack in the lever (locked the racheting mechanism)before kicking on the lever, it probably wouldn't happen again. Trials bikes get stopped and started more than any other motorcycle and the racheting mechanisms, especially the lightweight one in the Pro, can take a beating. Jon

On the Marzocchi forks try backing the compression adjustment screw out, not in, to make them faster (you can compress the spring a little farther-"store" more energy into it that will push out on rebound). You can also add, maybe 5-8mm to the spacer depending on rider weight. The factory oil level on the aluminum Zoke's is 160mm (spring out, upper tube compressed and air bled from cartridges) and the factory oil weight is 7.5. You might try a 5 weight or even get a little nutty with 2.5, but 5 may work well for you. If the weather is cold, the forks will be a little "slower" than warmer months, but keep in mind that different brands of fork oil have different actual viscosities (and can be measured in different ways and at different testing temperatures). The Marzocchi forks are set by oil level, not volume like the GasGas forks or even the 03' Raga (GasGas forks with Marzocchi internals) as the cartridges do not fully drain without taking them completely apart and the measurement of oil level is different for the steel tube than for the aluminum tube Zoke's. Cheers. Jon

I agree, you need to isolate the electrics as much as possible. Make sure the welder knows the frame material is ChroMoly, not mild steel and to keep the ground clamp as close to the weld area as possible. Jon

[quote name='copemech' Now it seems both Montesa and Scorpa are looking for a rider? Time to forward your resume in quick, Mark! I don't see the Scorpa factory picking up on the copemech talent too soon, as his past disparaging remarks about the French have poisoned that well of goodwill. However, I can just see Soichiro Honda spinning in his grave at 22,000 RPM's when he finds out Mark is on one of HIS babies...... Good news about Keith. A great person and talented rider and the Beta is a good, solid Trials platform for him. Beta USA is a good bunch of people and the partnership should produce some interesting results for the future. Jon

Mark, My vote is for you. You are one of the few people who consistantly is able to make me laugh when we're together at a Trial, especially when I get you mad, which is why I consistantly try to do so. Mark, like me, has a deep, cynical appreciation for the absurd, thus we are constantly finding things of interest happening around us, and it sometimes creeps into our conversations. And yes, in person and in print, he is the "real deal", and you don't have to worry about any hidden agenda. I vote Mark for "Commenter of the Year". Jon ps. Mark, I've heard your pigeon spanish, and my guess is that Caby was a little frightened and confused as to what you REALLY wanted signed.

If the rings are actually breaking, which is unusual, I'd look at the champhering on the ports, especially the exhaust, which is generally the widest one (and the area that heats the rings the most). You'll want to make the angle of the cut at about 15 degrees and widest at the centers (top and bottom) of the port (maybe about 1.5mm), tapering down as you reach the sides. A lot of mechanics will just "break the edge" of the port sides which will usually end up with a 30-45 degree cut, but the idea is to ease the ring back into the land and avoid dangerous harmonics in the process as they can contribute to ring breakage. Jon

A trick to installing a fork seal is to lube it first with a little fork oil (I like to pack the area between the upper and lower seal lips with Teflon grease). Cut a corner off of the lower part of a plastic sandwich bag (like a triangular hat) and put the hat on top of the upper tube and slide the seal on the tube. The plastic "hat" will keep the seal lips from hanging up on the top of the tube and it should easily slide on. Cheers. Jon

Mark, Didn't the Aprilla have the rotary valve (disc) Rotax engine? In piston port engines (like most 2S Trials engines), the piston is the "valve" that opens and closes the ports, so the port timing is always symetrical (if it opens the port X degrees ATDC, it will always close the port at X degrees BTDC) but in the rotary, the disc has a cutaway that opens and closes the intake port, so that by changing the cutaways you can advance or retard the intake port timings on an individual basis. I once built a wacko roadracer using a Kawasaki 350 Bighorn single and had several discs with different profiles to tune the engine for the specific track we were running on. Jon

Hi Alan! Actually, a bunch of small beer kegs stuffed in the tire works well also. You may not get the tire to seat, but after emptying the kegs, you don't care...... I made a, just for mounting tubeless Trials tires, valve stem attachment for my compressed air line that really pumps a bunch of air quickly into the tire. That, coupled with the tube trick has made mounting the tubeless tires a tolerable task. After thousands of tire changes (including the dreaded Barum and Trelleborgs) it's still one of my least favorite things to do with a motorcycle. Jon

If you live in the U.S., you can get a DVD/VHS video shop manual from TrialsPartsUSA: http://www.trialspartsusa.com/ . Otherwise, I think they have a hardcopy parts manual (exploded views and parts numbers) you can get. There is a downloadable 95' parts manual on the German Gas-Gas website: http://www.gasgas.de/ but it is virtually unreadable, unfortunately. Jon

I'm not aware of a hardcopy service manual (I'm assuming you mean a "shop manual" used by dealers and mechanics, and not an "owner's manual" used for basic maintenance and information) available for the 95'. Jon

Since I carry my TY350 around with my Pro I like to carry an extra 4.00X18 tube for it and store it in my spare 4.00X18 tubeless tire for the Pro. I inflate the tube enough to spread out the bead on the spare tubeless tire so when I need to mount the tubeless, it's taken a set with the bead spread well out so just a little soapy water pops it right on. Jon

graham, I'd replace that roller bearing washer before I'd ride the bike anymore, just to be safe. The little amount of grease should not do any harm, but that is a captured roller bearing thrust washer (the washer holes are pressed over on the edges to hold the rollers in place) and they should NOT fall out of the washer when it is removed. I doubt that they will fall out under the slight pressure the spring inside the servo cylinder post exerts, but they are obviously worn to the point that the decreased diameter lets them come out of the peened part of the steel cage and that may cause them to chatter and possibly disintegrate and they can do a lot of damage. Be sure to "re-assemble" the little rollers in the old washer when you remove it to be sure one isn't missing and look carefully at the wear pattern on the tophat and the washer that presses on the fingers to see if they need to also be replaced. If there is any roughness in the wear patterns, it will cause premature failure of the new roller thrust bearing. Jon