jse

Ah herd dat. Now you guys know why, when the Govenor of Texas, Rick Perry, threatened to have Texas secede from the Union, the rest of the States started passing around the hat to help with their moving expenses..... Hey Copey, see ya at the Central Regional Championships! Jon

Actually, the shaft will bottom out before the o-ring goes in that far. An adjuster in too far will cause (1) gradual lessening of the effective throw of the lever and (2) possibly brakes locking up (especially on the rear brake system when there is heat in the caliper from severe braking). Jon

Ian, The only thing I can think of that would cause the leak at that area is a damaged o-ring. On the M/C piston "shaft" there is the seal at the front and an o-ring at the back, which seals the non-pressure area where the circlip is. I'd carefully take the internals out and see if there may be a small scratch at the beginning of the M/C bore (maybe caused during installation) that may have caused the o-ring failure. Sometimes it can be carefully buffed out to at least cut down the sharp, upraised part. Jon

Your best bet is probably to contact your local dealer, who should be able to help you. This forum is generally devoted to Trials models. Usually the thin, stainless steel plates are backing for the pads as a brake puck heat shield/anti-vibration measure. Jon

Another quick shot. Jon

A couple of quick photos of it in it's present condition. As I say, it's a runner not a poser so it has it's share of scrapes and dings, and it sure is fun to ride. Jon

Yep. It is an obsession and I'm going on four decades of the "illness". It's easy to think you are the only one who does it because no one talks about it much. I can vouch that it's becomes worse the more Trials one sets up. Probably the reason is that we use natural terrain as our "racetrack", which, of course, is all around us and I would also guess that roadracers drive cars on the street and think of entrance speeds, apexes, braking points etc. I know when I was dragracing, stoplights made my heart beat a little faster.......... I think the "cure" is to just get out and ride more....... Jon

Good for you! Chances are that you'll get as obsessed as the rest of us now. There's something unusual about this sport, not sure what it is, but it can end up being a life-long pursuit, or at least 38 years so far in my case. The riding is fun and challenging of course, the bikes are cool, but I really think it's the people you meet at a Trial. Trials riders seem to have a slightly different psychological profile than competitors in all the other forms of motorsports that I've been involved in. They can be just as serious and competition-minded, but it's almost like we're all on the same team and banded together to solve a common problem, which, in a way, I guess we are as far as a section is concerned. I would expect you to have more fun as time goes on and you probably make some friends you will have for the rest of your life. There as some drawbacks and I must warn you, however, that now, when driving in the countryside, you will never, ever, see it the same way again. You will start to see each ravine, log, bunch of rocks, creekbeds etc as "Awwww, cool. I bet I could make a neat section there.....". I know I'm not the only one who still does that......... Jon

The key to good running on the 85/86 TY350's was a change in the combustion chamber design (very much like the early Honda CR500's-great engine, but poor execution of the head design). The trapezoidal combustion chamber was the rage at the time and, although workable, it was not as effecient as the later hemi, and when matched with an overly wide squish clearance in the 350's (usually measuring 2.5mm on up on the TY's I've checked- 1mm would be the design target) it produced a rattling, wheezing response-especially when the engine got hot. The TY 250's of the era were a better running engine (affected to a lesser degree by design parameters), but we got the 350 here in the U.S. almost exclusively. I'm guessing that the marketing department at Yamaha felt that the "small" engine wouldn't sell well here in the land of "too much is just right". It would seem that the theory still is in effect to a degree, with the larger 280/300 engines popular here and the 250's seem to be more popular in the rest of the world. The 250's are making a small comeback in the U.S. as newer riders have a chance to ride the bike and find that the power is more than adequate. Maybe we will get fewer "how can I soften my bike's response" questions... For the higher altitudes, the 280/300's still make good sense. I machined the TY head to a hemi configuration and use a .003" copper head gasket with the squish set to .039". Never a rattle or signs of overheating and the throttle response is like a newer type engine. Jon

Actually, I can't think of any modification on the bike that didn't provide the improvement I was looking for. I do, however, spend a lot of mental time/visualization on the mods before fabricating them so the actual building is fairly easy. I just manipulate the material I'm using to fit the mental image, kinda weird I know, but I doubt I'm alone in this. I'll take some photos when I get it back together. It's not a Concours show piece, but is designed for hard riding. I guess that after riding it for 24 years, the changes now and then make it still fun to use. Jon

Well, since the A/C Mono forum has gone a little silent, I thought I'd throw something in for us to chew on. This 85' TY350 has been in the family since we bought it new and I like to ride it at our Vintage events in Non-Comp, just-for-fun class. It has become a test mule for my wild-hair, "hmmm, what if we did that?" brainfart projects and has been modified so many times it starts to whimper when I walk in the shop door. Photos are of a couple of the latest changes: I revalved a Works Performance shock, added a steel-braided line and a adjustable remote reservoir. The intake is a one-piece reedcage/manifold I made several decades ago and uses early CR125 dual-stage reeds. The internally modified Mikuni flatslide 26mm has a machined sleeve to extend the spigot. Anybody else out there doing weird things to TY Monos? Jon

You are probably lucky you didn't break the centercase when the chain packed in. The forces involved in a gearbox from a sudden lockup of the countershaft are absolutely huge, especially in a Trials engine with the very large inertial energy stored in the big, heavy flywheels we use. As a somewhat related aside, and in the area of TMI regarding chains and sprockets, because we use chain tensioners on our bikes, we almost never run into a fairly common problem with MX bikes, that being, centercases splitting at the countershaft case bosses because the chain was not allowed enough slack. Sometimes, if the rider was fortunate, the chain would pull apart before the cases split, so I would always look for the telltale signs of stretch fatigue on the links for a diagnosis. MX riders, like Trials riders, usually adjust the chain with the bike up on a support with the swingarm below "level" and sometimes forget that the rear axle pivots, not in a circular arc (the pivot center is the swingarm shaft center, not the front sprocket center), but a parabolic arc which causes the chain to tighten tension at the "level" point. Hmmm, I guess the point of this rambling is to offer that it is better to error on the side of a little too loose than a little too tight when making chain adjustments. Jon

Not sure what the free length measurement is, but go to: http://www.trialspartsusa.com/tech.html for suspension info, you should find what you need there. Jon

A 90 degree nipple should work fine, provided you removed the spring/ball one-way valve where the gun tip would ordinarily attach. Otherwise, you are running a "non breathing" breather and this could cause problems up the road, especially with the seals. Jon

And, if you look in the photo gallery, you'll see a photo of the rider who placed 14th..... Jon

More than likely, the K&N filter oil you used (probably red in color) was for a different type filter element (a trapped-layer gause type that requires a little different flow agent and final viscosity). I'd use a filter oil that is specific for "foam type filters". Jon

Not sure the difference buying the dogbone complete, but they are not difficult to press in and out using long sockets, one to fit the outer diameter of the bearing outer race and a larger one to hold the dogbone end and press the bearing into. Also be sure to check the bearing in the lower part of the swingarm, it's often forgotten. Don't try to hammer it out from one side, there are two "tophat" bushings that fit in either side. Use a sharp edge punch to catch one in the center of the swingarm bore and drive it out. Look inside the swingarm bushings and you'll see a dividing line in the center (that's where the "top" of the hats meet), that's where you need to catch the end of the bushing opposite you and slowly drive it out the other side. Jon

The 9T, 520 chain, countershaft sprocket tends to be hard on the chain (tooth/bushing engagement is fairly brutal at that small diameter) and you would more than likely experience accelerated chain wear. Most of my buddies with 4RT's have opted for a 10/44 combination and tell me that some of them have even used rear sprockets from the smaller displacement GG Pro's (44T is standard on some the smaller displacement Pros and reportedly also fit the Montesa hub) when their dealers ran out of them. They say the 10/44 combo tightens up the gear ratios nicely, allows less clutch work in slow section areas and they can use a higher gear for climbs. Jon

Usually the only thing that wears on a cylinder is the bore plating, so an exchange is the best bet. Before you put everything together, you might do some serious "failure analysis" (an unfortunate, but necessary proceedure from my old dragracing days....) and find the cause of the unusual wear that produced your symptoms. Look carefully in the bell of the carb and the intake boot and if you have deposits of fine grit, the air filter and/or airbox is causing dirt to enter the cylinder. I would always advise that you should never "fix" anything until you have determined the cause of the failure. As the Pro engine has the main bearings lubed by the gearbox fluid, grit will not usually cause them problems (provided the engine has had regular maintenance) but you might look carefully at the rod big-end for ANY straight up/down clearance (wobble and side-to-side clearance is not unusual). You might also measure the ring end-gap as that will be a direct indication of the amount of wear. Standard assembly tolerance is to have 0.1mm per inch of bore diameter, so you can compare what you find to what the ring started at. Jon

Gordon, The 26PHBL will work fine for a new rider with your bike and you would probably have some difficulty, as a new Trials rider, sorting out a smaller carb and , in fact, the throttle response would be quicker (not good for beginners). Get the stock type carb and we can help you get it set up and then give you some pointers as to how to soften the engines response so you can have an easier start in the learning process. The low-end rsponse possible with this bike is more than you need at the beginning (and will probably be too much, which is why you may want to tone it down). "Sorry for all the questions"......not to worry, that's what this forum is mostly about. Jon

I agree, the wiring diagram is a good place to start. You'll notice that there are actually two seperate power generating systems, one dedicated to the CDI ignition and the other to power the lights, horn and fan (there are different generating coils in the stator for ignition and accessories and they are not interconnected, although most riders often think there is only one power source). Depending on where you cut the wires, you may have cut the power to the fan (the red wire in the 99/2000 diagram, but often it is yellow to the fan). I'd trace down the harness and you may want to take off the "extra" stuff you do not need while you are at it. You WILL want to install a killswitch in the process, as you have probably also cut the killswitch wire housed in the handlebar switch assembly. Jon

Well, back home and unpacked. Here's photos of my Saturday section 2 and Sunday section 1 (the mudhole/cow pie section). Good warmup sections with mostly cleans (if you could say that about the mudhole). The cow pie section on Sunday was at the only creek crossing/watering hole through the moors the cows liked so I bravely battled about 50 cows to keep control of the section in the hours between the first and second loops. The calves found that section tape was a wonderful dessert. Jon

A quick post from Sante Fe, New Mexico on the way back home from the Ute Cup. It was, in a word, great! They have gone back to the old format. Intermediate/Advanced level sections so the Trial is geared for the average Intermediate rider, long loop (22 miles on Saturday, close to that Sunday) and ride the same sections twice (two loops each day). 20 sections on Saturday and I think 16 on Sunday. I probably had 20+ riders tell me how much fun they were having. More to come later....must....sleep.....now.......... Cheers. Jon

I think you may be confusing "airspace" with "oil level" and although they may look the same, they are somewhat different measurements and related. "Airspace" is the space created at the top inside of the fork tube based on the level of the oil in the fork, completely assembled, at full extension. "Oil level" is the level of the fork oil from the top of the tube, spring removed, all air bled out of the cartridge and the fork tube completely collapsed into the lower leg. Oil level is how you determine the airspace in the assembled fork. How much volume the spring takes up when added to the fork internals will also have an effect on the amount of airspace in the assembled fork. As far as I know, the aluminum Marzocchi forks are set at an oil level of 160mm and the steel tube Marzocchi's are set at 180mm. Jon

You can try using Dexron ATF. It's about 7.5 weight and has the fork oil properties you need. I doubt anyone on this list could tell the difference between 7 and 7.5 weight when riding the bike. Advertized "weights" in oils are an general approximation only, not an absolute measurement. There are other ways to rate viscosity other than the SAE "weight" so that's why you see other numbers on a bottle of fork fluid and they relate to SUS (Saybolt Universal Seconds) and "VI" (Viscosity Index) and an example of that would be a "85/150" marking on the bottle. Try the Dexron, you'll like it. Jon