fastducs

No, you don't have to replace the shock just because it is leaking. I had mine rebuilt by a suspension specialist, and it wasn't that expensive. Furthermore, the damping adjuster on mine was broken internally, so he machined a small batch of replacements because you can't buy them from Showa. If your adjuster is seized or broken, you can buy one from my suspension guy: http://www.computrackboston.com/ If you want to replace your rear shock, Lewisport carries TRP shocks for Montesa, Sherco, GG, and Beta Evo: http://www.lewisportusa.com/Images/TRPshocker_a.jpg http://www.lewisportusa.com/parts_wheels.htm

Everything about these little bikes is a mystery. I suggest the way to figure out the answer to your question is this: get a hold of a parts diagram and see if different thickness base gaskets are available. Additionally, you can measure actual squish clearance of your engine. You can find rule-of-thumb clearance numbers on the web.

Jon, are you saying that when the temps drop below freezing, the cylinder shrinks enough (relative to piston) to create an interference fit? I.e. the piston is physically seized in the cylinder?

Good on you David! When I was shopping for a GG-50 I was told to steer clear of anything prior to 2003 because of the ignition problem. Looks like you've found a solution. Nice! Generally speaking, GG doesn't have any info on this little bike anywhere. Looks like community-based info is the only way we'll be able to maintain these bikes properly. I wish I had enough web space to put together a GG-50 knowledge base. BTW, does anyone know of a flywheel cover protection plate that I could buy? Turns out this bugger is plastic on my son's 2006 model, and after one left-sided crash the spinning flywheel gouged that flimsy plastic all the way through.

Yup, that was me. Sorry, I should have posted an update, but since winter is here and our riding season is over, we only tested it in our back yard rather than on real sections. I removed 2 of the 4 springs, and I'm pleased with the results. My son says the bike has much more power now, but I think he really means the engine is more responsive and predictable. I've also noticed that prior to the modification my son would constantly blip the throttle, probably because the clutch would hit too hard, so he would immediately back off the throttle, and then repeat this on-off-on-off cycle constantly. After the mod I noticed he is using nice steady throttle. An added bonus is that the clutch lever pull is much easier too. And because I stayed with original clutch plate arrangement, there is no drag, and it shifts easily.

As a first bike, Oset is the perfect choice! My son started on an Oset 16 with the 36-volt kit when he was 5. Because the Oset is so quiet, he was able to practice a lot right in our back yard, and in the park where a gas bike would simply not be tolerated. Now he is 7, and moved up to a gasgas-50 trials bike. He also races a KTM-50 in the PeeWee hare scrambles series. I think the Oset is excellent because it teaches kids to ride standing up, which is an advantage on ANY bike that they will move on to. Stand-up get-offs are also much safer than sitting-down crashes. I think the first lesson should be "how to bail off the pegs, then tuck-and-roll safely". Beware that Osets tend to come over-tightened from the factory. I've seen it on several brand new Osets. Particularly the rear swingarm and suspension is over-tightened to the point that it barely moves. Remedy is easy: take everything apart, re-grease, and reassemble without over-torquing. I don't know about the 12.5 model, but on the 2009 Oset-16 the front fork springs were much too stiff, and the rear shock too. After I re-sprung both ends, the suspension became much much nicer.

Look at the online parts fiche here: http://www.apexmotosports.com/montesa%20parts%20book/e-1.htm Headstock bearings are actually a standard Honda part 91015-425-832. Same goes for the wheel bearings. Wheel hub spacer tube has a shoulder machined into it on both ends, so it protrudes half-way into the inner bearing race. Great for centering everything, but a PITA to remove. The easy way is to have a friend turn a mating piece on a lathe, so it looks like a piece of solid cylinder with a step-down. The smaller diameter is same as spacer tube I.D. and larger diameter is same as wheel bearing inner race I.D. It is important to have this step-down because it protects the tube from crumbling when you are hammering it out. Also, heat up the aluminum wheel hub with a propane torch. Aluminum expands more than steel, so it will require much less force to hammer out the bearing.

Lewisport sells aftermarket shocks for about $600 if memory serves me right. But you can have your OEM shock rebuilt by a suspension shop. I don't mean a bike dealer, I mean a real suspension specialist. There are a few of them throughout USA: - RaceTech (http://www.racetech.com/) - Factory Connection (http://www.factoryconnection.com/) - MX-tech (http://www.mx-tech.com/) - GMD Computrack (http://www.computrackboston.com/) GMD Computrack Boston rebuilt my Montesa 315r shock for about $120 a few years ago. If you don't have a local suspension expert, then call Peter Kates at 508-876-9407. Shipping in the continental USA should be about $10 each way. Right now is the slow season around here, so it's the perfect time to get your suspension serviced. I was originally told that my Montesa shock wasn't rebuildable, then I was told that I had to send it to some guru in California to get it worked on. Turns out there is nothing mystical about trials bike suspension. Peter has done suspension work for me before, so I brought the shock to him. He told me that it's just a simple gas-oil-emulsion Showa shock, and rather primitive by comparison to state-of-the-art MX and roadracing shocks. He rebuilt it without any problems.

I've dealt with partial cracks by "stitching" across it with small zip ties. Drill a small hole at end of crack to stop it from spreading further. Then drill series of holes on both sides of the crack spaced about 1/4" away from the crack, and about 1/2" from each other. Here is how I fixed my rear fender which I broke completely in half. I used a hacksaw blade about 16" long as a "backbone" underneath the fender, and riveted it in about 8 equally spaced spots. I also used 2 short segments of hacksaw blade (about 4" long) mounted underneath the fender, but running along the side edges. It has been holding up well so far. The hacksaw blade is made of flexible "springy" steel, so it bends together with the fender. As a finishing touch I added a strip of red duct tape to cover the blade. You still see the rivet heads on top of the fender, but they just add a little special "character".

I just noticed something very interesting in the parts list for the clutch: Clutch Parts #13 Clutch spring TXT50: MIT50032015(2) / EC50: MIT50032015(4) According to this parts list, EC50 should have 4 clutch springs, but TXT50 is supposed to have only 2! In reality my TXT50 has 4 springs. Reducing it to 2 springs will soften the clutch hit and make it engage at a lower rpm. Could it be that due to a parts-room mixup the factory is installing the same clutch assembly into the TXT50 trials bikes as they are installing into the EC50 enduro bikes? Could it be that TXT50 engineers designed it to have only 2 springs, and therefore a much softer clutch? Could it be that the popular 2mm clutch plate modification is really unnecessary, and the right "fix" is just to remove the "extra" 2 springs?

What exactly was leaking on your water pump? Mine clearly has a damaged o-ring on the outside of pump body. I'm tempted just to replace that o-ring without messing with the internal pump seals. I got the water pump out. Came out just like your mate said: remove clutch, undo 1 bolt which holds waterpump body, and then pull the pump out. That last step is easier said than done because the pump body has 2 o-rings that make it sit very tight inside the crankcase. I had to get clever about it. With the pump still in place I tapped 8 mm threads into the pump boss (the one through which that one pump bolt goes). Then I screwed in an 8 mm bolt, and gave it a good pull. Looking back at it, I think there is another way to remove it. It might be possible to use compressed air to pressurize the cooling system through the radiator cap, which in turn should push the pump out of its hole. Just be prepared for a gusher of coolant when the pump comes out, and have a friend hold on to the pump while you're pressurizing the system, or else it might become a dangerous projectile.

Smudger, thanks for the parts diagrams, they are very helpful. Do you by chance have diagrams of the forks? How did you remove the water pump? Did you have to split the cases, or does it pull out somehow?

I disassembled the forks: http://users.rcn.com/vmoathome/txt50/internals.jpg and found explanations for the leaky seals and lack of damping in the right leg, but unfortunately what I found only raised more questions. (1) The leaky seals were caused by foreign material stuck inside the seal lip. Both fork legs had this problem! It looked like a piece of red mylar film. Here are some photos: http://users.rcn.com/vmoathome/txt50/seal-with-mylar.jpg http://users.rcn.com/vmoathome/txt50/mystery-mylar.jpg What is it? Where did it come from? Has anyone seen anything like this before? (2) Lack of damping in the right fork leg is explained by the fact that the right damping rod is missing a black plastic piston ring. The left and right damping rods are almost identical, except that the left one has a piston ring, and also a very small bleed hole just below the topout spring. Here is a closeup photo showing both rods: http://users.rcn.com/vmoathome/txt50/damping-rods-closeup.jpg My first thought was that the plastic piston ring from the right rod simply shattered, but I couldn't find any evidence of it when I drained the fork oil. Plus the extra bleed hole in the left rod makes me suspect that perhaps the right rod isn't meant to do any damping? Any thoughts on this? Should I just add the "missing" piston ring and see what happens?

I've looked everywhere for a parts diagram or a workshop manual for the boy-50 (mine is a 2006) but no luck at all. I spoke to one GG dealer who said that even he didn't have access to a workshop manual, in fact maybe GG never even published one. So if you find anything at all, please post where you got it. Also, if you don't mind, please take pics of both your projects, as they are on my winter project list.

You can bevel the edge of the piston with emery paper. Assuming you installed the seals facing the proper direction, you should be able to lube the seals and the piston with brake fluid, and then push the piston in. Use a C-clamp rather than brute force, as the c-clamp lets you do it nice and steady while controlling alignment. Here is what I do to help start the bleeding process: 1) Unscrew the brake line from the caliper. 2) Make sure piston is sticking about half-way out of the bore. 3) Fill caliper with brake fluid via the brake line hole (where the banjo bolt screws in). Syringe with needle works well for this, as it allows you to stick the needle all the way into the bore and fill it with fluid. 4) Push piston into the bore until brake fluid starts to overflow from the brake line hole. 5) Screw in the brake line. 6) Bleed as usual.

Greetings. I'm beginning to familiarize myself with a used 2006 TXT Boy-50 that I've just bought for my son. The forks are off of it at the moment, so I gave them a quick individual look-over. It seems the right fork leg has no oil in it. I haven't peeked inside the fork leg yet, but I noticed that when I stroke the left leg I hear fluid slushing inside and feel some damping. But when I stroke the right fork leg, it feels like there is no fluid inside. BTW, it looks like the seals on both legs are leaking. So the question is: how much fork oil is each leg supposed to have? And what weight oil to use? I would be very grateful if someone can tell me where to get a Workshop/Service Manual. Also a parts diagram would be useful. I have the User's manual, but it doesn't have any details on maintenance or repair procedures.

Thermostatic switch is in the radiator. It controls electrical current to the fan. It is the only thermostat-type device on this bike. There is an electrolytic capacitor which is part of rectifier circuit that makes the fan run. It is physically located in a rubber housing next to CDI box. If that capacitor is bad, or connection is bad, then the fan won't run. Troubleshooting procedure: unplug wires from thermostat and short them together. Fire up engine, and fan should immediately run. If it runs then thermostat is the problem. If it doesn't run then have a close look at the capacitor, and then the rectifier. Good luck.

I assume by "eating plugs" you mean that the plugs get fouled? I run 80:1 oil:gas mixture, and I have an iridium plug. I've also taken the trouble to jet my carb pretty well. I've been on the same plug for the last 3 years. First suspect is the carb jetting. Second suspect is ignition misfire. Also worth checking are the reeds and crankcase seals, which can be determined with a leakdown tester. BTW, 36:1 is too much oil in my opinion. This kind of ratio is used for MX racing when the engine is WFO most of the time. For trials riding this much oil will end up in the crankcase. Furthermore, this much oil actually makes your fuel:air ratio too lean, so if you insist on mixing 36:1 then you need to compensate with richer jetting.

Yes I've opened up the forks on my son's 2009 36V Oset-16. They are terrible. Yes there is a spring inside, but it is very stiff. I went to the hardware store and bought a bunch of different springs, and then played with mixing-and-matching springs until I got the forks to compress reasonably when the bike hits big bumps. Unfortunately internal construction is so poor and clearances are so huge that there is a lot of stiction and binding. I sprayed internals with light oil, and it helps a little, but the right "fix" is to replace them with better forks. A friend of mine replaced them with RST Kappa T9 20" mountain bike forks. I think the latest-and-greatest "Pro" Osets use this fork, or maybe I'm thinking about Oliver's personal bike.

Showa forks do NOT have a drain at the bottom. I am not 100% sure about Paoli forks, but I remember looking at a service manual for a '99 cota, and if memory serves me right, Paoli forks do not have a drain bolt either. The bolt at the bottom is a damping rod holding bolt, and it is a bad idea to use it as a drain bolt. First of all, you won't be able to drain all the oil this way, especially the nasty grime that accumulates at the bottom of the fork. And if you are unsure about how much oil is left, then how will you know how much fresh oil to add? Secondly, there is a good chance you won't be able to tighten that bolt back to proper torque because you need a damping rod holder to do it right. It is much simpler to remove the forks, unscrew top caps, and drain the oil. Here is a little tip: step 1: Loosen fork pinch bolts in the top triple clamp, but not in the bottom triple clamp. This makes it easy to loosen fork caps. step 2: Loosen fork caps, but don't unscrew them completely. step 3: Loosen fork pinch bolts in the bottom triple clamp and slide out the forks. Now you can unscrew fork cap completely, turn fork upside down and pump it to drain everything.

My son weighs about 50 lbs, and his 36V can not lift the front with motor alone. The kid has to learn proper body movement to do a wheelie.

How about this one: http://www.motionpro.com/motorcycle/partno/08-0349/

Nice writeup, Dan. I'm no expert, but your theory about the glue blocking escape path for the oil makes sense to me. BTW, I wonder how many tabs of a friction plate are really in contact with the clutch basket. I figure it's probably only 3 tabs (or maybe it is only 2) since the friction plate is free-floating relative to clutch basket center center. But of course it isn't the same 3 tabs all the time, so as you go through clutch engage/disengage cycles, it randomly "picks" which 3 tabs are pressing against the basket. That's why over time all of the tabs get worn down. Anyway, if I'm right about this, then I don't see any benefit in trying to match tabs precisely to the basket fingers. For those folks who prefer to keep all 6 springs but would like to reduce clutch lever effort without spending money on lighter springs I can offer this trick borrowed from www.thumpertalk.com. You can use a washer under the spring retainer (obviously you will need 6 identical washers). Effectively this lengthens the spring "tower", or to put it another way, it reduces spring preload. Washer O.D. obviously needs to be slightly smaller than spring I.D. And washer I.D. needs to be just barely big enough for spring bolt to go through. I've done this mod on my enduro bike, and with 1.5 mm thickness washers the difference in clutch effort was very noticeable. The only thing to watch out for is to make sure you have adequate clearance between spring bolts and the clutch cover. This works because springs are position-sensitive. If you have a spring rated at 1.0 kg/mm then it takes 1 kg of force to compress that spring by 1 mm, assuming the spring was completely uncompressed to begin with. And it takes 1 additional kg of force for every 1 additional mm of displacement. In other words, it takes 3 kg of force to compress a spring from its free length by 3 mm. If you have a certain amount of preload on the spring, then the force required to overcome the preload is exactly the force it would have taken to compress that spring from its free length to its installed length (i.e. down to its preloaded condition). So if the clutch spring free length is 30 mm, but its installed length is 25 mm, then you have 5 mm of preload. If they are rated at 1 kg/mm and you have 6 of them, then the force required just to budge the clutch pressure plate is 30 kg. If you reduce preload to 4 mm (by using 1mm washers) then the force is only 24 kg.

Hello proud parents. How do you teach your kid how to wheelie on an Oset? My son really wants to do them, and he practices in the driveway going over a log for countless hours, but I can't seem to explain to him the proper way to use his body motion and coordination with the throttle. I'm not talking about doing any kind of long distance wheelies, he is simply struggling with being able to lift the front on demand. Anybody willing to share their teaching aides or tricks?

The bars are 7/8" steel bars. The bar ends I used are the aluminum expandable-insert-style that you use for full sized trials bikes, but the end which inserts into the bar wasn't thick enough. So I simply wrapped enough electrical tape until I got it to fit tight. I don't even bother trying to expand them with the bolt, I just tap them in with a hammer. Removing them requires tapping in the opposite direction with hammer and punch. They work great, and saved the throttle countless times. If you replace the brake levers, make sure you get the right amount of leverage. I replaced them on my son's Oset-16 with what I thought were much better levers, but it turned out the new levers produced less clamping force than the original ones, so I reverted back. BTW, while you are messing with the levers, I recommend putting some teflon tape under the clamps to keep the levers from bending due to a crash. It's a standard trick on all offroad bikes.