jse

My first guess is that the flywheel hub has slipped on the crank stub and sheared the Woodruff key. This will throw the ignition timing off and can cause the symptoms you describe. You'll need to pull the flywheel off and check the key (a half moon shaped piece of metal that fits in a special groove in the crank stub) to see if that's the cause. What model and year is your son's bike? Jon

If you live in Santa Cruz, you might check in at Moore & Son's shop at 2-1431 East Cliff Drive. Johnny Moore is a Trials dealer for several brands, including GasGas and may have an idea of where you can send it that may be close. Tell him that Jon Stoodley sent you to him for his sage advice. Jon ps. Santa Cruz is my home town.....

A note for future reference, use a gloved hand to plug the exhaust end and the other to hold the kill switch. Two-strokes tend to auto-ignite at full chat in neutral, but plugging the exhaust will usually bring down the RPMs to the point where the killswitch will work. Jon

If you are looking for simplicity a pod will work. If you are looking for long-range performance a well designed airbox is probably better. Besides insuring better quality air, the airbox/boot system helps shape the incoming air mass in a way that allows the carb to make better use of it. Some time ago I ran a series of dyno tests on several 600 SuperSport roadrace bikes and used several types of individual aircleaners (foam and cotton gauze)/tuned flared tubes (four carbs) and the stock airbox. Although the tuned intake tubes gave a slightly better top end HP reading, the airbox consistantly gave better low-end, out of the slow turn pull type of torque that wins races. Jon

That plug should work fine set at .024". I'd probably start by checking grounds near the CDI and connectors to be sure a wire is not loose. The Kokusan system is pretty stout and should fire it right off. Black plugs can be a symptom of several problems and oily (wet) or sooty (dry) make a difference in diagnosis. Jon

What type of plug is in the bike and is it the original one? Jon

Sounds good. The cross pin usually breaks on impact to the lever, but not always. Hopefully you are in good shape. If you wiggle/twist while pulling on the top hat, it should come off easily. It's supposed to be a tight fit. Those little needle bearings should not be loose. That's an indication of advanced wear, so you'll need to replace that bearing thrust washer, obviously. If you are missing any (put found ones in the washer housing just to be sure you have them all), you might try putting the bike upright and with drain plug removed, squirt solvent into the inside engine case to try to flush them out. I think the newer bikes come with magnets on both lower and upper drainplugs rather than just lower plug. I run magnets on both plugs on my 02" Pro. Jon

You might be o.k. I agree, you should always check the simple things first. There's a 4mm head capscrew holding an eccentric bushing with a 10mm head and the tangs of the centering spring go on either side of that bushing. You may want to take that off with the "top hat" to make it a little easier the first time. The centering spring and top hat assembly pull off the end of the shift shaft that protrudes out of the case. It's a good idea to start with the bike in neutral, but not an absolute necessity. If you look at the top of the "top hat", there is a piece of metal that goes across and that piece fits into the slots on the end of the shift shaft (it will be more clear when you look at it). That piece of metal often breaks off from the top hat in a shunt with a rock, but then you usually do not have spring pressure on lever unless the piece is catching slightly. Jon

That works well. Obviously keep fluid up in the M/C reservoir, but this should take the air out of the line and give you a little pressure. You can then use the bleed screw on the caliper to get air out of the "loop" at the top of the caliper housing. Some calipers have a "dead" area on the side opposite the bleed screw and in a pinch you can take the caliper off the fork, put a piece of plastic sheet or metal in between the pads to keep them from coming together and rotate the caliper to move the bubble over to the side with the bleed screw. Usually you don't have to do all this stuff but sometimes it is necessary in rare cases. Jon

You'll always want to inspect for damage before ordering parts. The shift centering assembly is under the clutch basket and is removed by taking off the circlip, but you may have damaged the shift rollers on the internal shaft and that will encompass splitting the cases. The rollers have a built-in stop, which in your case, is not working now as the arms that hold the rollers may be bent. If just the centering spring assembly is broken, as I remember, the shaft will not rotate 360 but still be limited in rotation. Jon

Make sure the M/C piston is coming all the way back to the stop (you may need to back off the adjustment screw on the lever) and tilt the M/C up to avoid a loop in the hose. If you press the lever in/out gently with the M/C raised up a little, you should notice small bubbles coming out the bleed hole. Keep doing this until they stop coming out and then you should have enough pressure to start pressure bleeding the caliper where air bubbles hide. Jon

I would guess that the four-stroke would drop into the two-stroke frame easily due to it's size so one could have a choice of engines. The programming of the EFI and ignition curves would allow a rider to choose exactly how the engine would produce power and it should all be downloadable from the Internet. Jon

One of the things I've done to keep water from being trapped in the stator area is to vent the sidecase on all my bikes since the 70's. This really helps in a wet Trial as the sidecase is a closed container of gas (air in this case) and if cooled rapidly (like in a creek) a vacuum will form and suck water into the case in any area where the gasket/seal is compromised. A cut down Schrader fitting can be used or any small fitting that a hose can be attached to. The hose is then run up under the fuel tank and into a small coil. I check my stator once in a while and spray some WD-40 on the surfaces just to cut any corrosion possibilities. It's been clean and dry for 8 years now. This is my 02' Pro vent, which is really needed as the 02' engine is non-anodized Magnesium and really prone to corrosion if not cared for. Jon

My guess it that it's the economic climate rather than technological limitations that are delaying it's introduction. My take on the sidevalve: http://www.gasgas.com/docs/gg_4str_stood.pdf . Jon

Provided there is (1) adequate fluid in the M/C reservoir, (2) no leakage of fluid at the fittings (loss of fluid volume) and (3) the lever pressure is good/solid after pumping it up (no compressible air in the system), my first guess is worn piston seal in the master cylinder. If the rubber boot that the M/C plunger goes through is compromised at all, the chances that the seal is bunged are that much greater. What will happen if the boot is broken/missing is that fine grit will get into the bore and wear the seal lip. Even with normal seal wear the symptoms will be similiar. We usually use about the first 1/3rd of the master cylinder bore in normal brake operation so that after a while the first 1/3rd of the bore will be a slightly larger diameter than the rest of the bore due to normal wear. When the seal lip is worn to the point where it looses tension with the walls of the bore, when the lever is pulled and the piston starts to travel, fluid will pass by the lip until the seal gets down into the unworn part of the bore (smaller diameter) where it will seal again and pressurize the line. With a little pressure built up in the system the seal, due to it's shape, will expand out a little and be able to start pressure at the start of lever travel. If the brake is not used for a time, the seal will relax (become slightly smaller diameter) and the process starts again. My bet is that if you put in a M/C rebuild kit, the problem will be solved. Jon

"Jon: Was just re-reading through this old post of yours and saw you mention Whitey Webb! He still lives here in my hometown of Victoria BC Canada. There is a great connection between Kip and Whitey and myself. Us Canadians like to know that there is some good Canuck bloodlines in that Webb family. Great people all of them! Steve" Great news! Tell Whitey hi for me, but it's been so many decades he may not remember me (heck, sometimes I don't remember me.....). Whitey was at the PITS booth for a big motorcycle show at the Cow Palace in South San Francisco I went to after getting out of flat tracking. His passion and dedication to Trials was infectious and got me interested in trying it. The rest, they say, is history. The meeting was casual, but looking back, had a dramatic (and positive) impact on my life, that's for sure. He may be part of the reason I like to go over and meet new riders at our events and take them out to ride their first Trial, showing them the rules and give them a short lesson in riding and reading sections. I had been involved in a lot of types of motorsports competition up to meeting Whitey, and he was so different from the gunfighters I had previously competed with, as were all the other people I first met in Trials, that I figured I had found a "home", which after 39 years, is more true than ever. Jon

I have an 85' TY350 with a Talon conversion. I ordered a M/C kit from TrialsPartsUSA/AJP America as a backup : http://www.ajpamerica.com/rebuild-kits-and-parts.html that looked like it would fit but have not needed it yet, so haven't had a chance to check it out. I'm not sure where you could get parts in the U.K. Jon

The Pro stator is a fixed item and non adjustable. When re-fitting make sure the places where the stator plate contacts the engine cases are clean (a little sandpaper works well) and I like to put a dab of dielectric tuneup grease (Silicone grease) on the contact points to ward off corrosion. The ignition timing does not involve stator plate position but is a function of crank angle and magnetic pickup sensor location. Jon

Andy, There should be special high-temp o-rings (usually an orange color) inside the female connections of the mid-muffler and final silencer. Jon

This sounds like an adjusting of the shift centering spring under the clutch would probably fix the problem. The other possibilities are a damaged roller assembly inside the shift drum or a bent shift fork, but the centering spring adjustment should be the first step. I would not recommend shifting the transmission without using the clutch. Trials transmissions are designed to stay in gear and not be shifted under load. Jon

I'm not aware of a reliable test the average rider could conduct that would yield fool-proof results. I would: Run the car down low of fuel, dump the can in the tank and top off with pump fuel. The exhaust convertor shouldn't be damaged by a little formulated-to-burn premix oil at the temps they are designed to run at, it's tetraethyl lead in fuel that fouls them and coats the perforated cores (I'm assuming the jerrycan is of pump fuel and not high lead race fuel-which is generally not available now anyway). The premix ratio in the car tank with the added pump fuel should be at about 80/120:1+ at least, which is probably no worse than if you added any number of oil-based fuel additives people use that are available at the auto parts stores. The engine might even be a little happier for a while with the slight amount of added lubrication. Get a fresh batch of fuel, do NOT add premix oil in the future and use a smaller fuel container each time to mix up what you will use in a days riding, which will be a better bet for your bike's engine. Jon

Ready mix for bikes should work. I use a 50/50 mix of auto anti-freeze and distilled water with a little Water Wetter added to improve heat transfer from alloy to coolant. Jon

Good for you, Pat. With all the external pressure on you I know it must have been a very difficult decision. You're an inspiration for all the riders here and I, for one, support your doing what is best for you 100%. Jon

I have a somewhat unusual request. I've had a Trials related e-mail relationship with a young man who recently passed away. His widow contacted me about finding a good home for his favorite Trials bike, a 2002 Pro (Jordi Pasquet's as I remember) and I said I would help her find a good contact. She lives in northern central Illinois in a town called Utica. I thought it might be in the NITRO club area but was not sure. If there is someone in a club in that area that could help her and maybe help a new rider find a bike, I'd greatly appreciate it. You can PM me off the forum. Thanks. Jon Stoodley

I'd heard about the MX/DT possibilities, but they seem rare also. I had a friend at the local Yamaha parts counter check the Wiseco listing for bore sizes but nothing came up close. There are a lot of the 350's here and I would expect any info you uncover will be helpful, thanks. Jon