jse

Compressed air usually works but sometimes a piece of grit will restrict a jet and a very fine wire is the only way to dislodge it. Jon

Tom, You probably want in the range of a 116-118 main and at least a #36 pilot (they sometimes come with a #35), usually a #38 works better. The restricted filter would make your jetting richer, not leaner, so my guess is a jetting problem. Jon

Yipes! Speaking of locking up engines (!) this reminded me of an old trick I learned many, many years ago about how to lock the two-stroke crank up to, say, tighten the flywheel bolt when at a Trial (no air for the wrench available) and I still use it now and then. Use about 2 feet of 3/8th cotton or pliable plastic rope (very easy to carry in a tool chest), put a little in the sparkplug hole, move the piston up to find TDC, back the piston back enough to push some rope in the hole to fill the combustion chamber and them push the piston up till it stops the crank. You want to be careful not to back the piston down too far and have the rope go into a port, but it's pretty foolproof and won't damage anything. After doing what you need to do, back the piston down a little and pull out the rope. Jon

The main crank bearings are lubricated by transmission fluid in the Pro. I wouldn't worry if a little oil is at the bottom of the case. It is usually a mixture of normal condensation and premix oil that has settled off the walls and is normal. Jon

"JSE, wouldn't happen to be Jon Stoodley Enterprises? The Gas Gas Guru? I could be barking up the wrong tree on that one. I am great at embarrassing myself on the internet." Guilty as charged. Don't feel too bad about embarrassing yourself on the Internet, Jay, I think I've cornered THAT market..... On the squish measurement proceedure, I've found (unless you are looking for a full chamber casting mold) two pieces of soft solder formed into curves, inserted through the sparkplug hole-one to front and one to back to compensate for piston "rock"- and then the flywheel rotated with a wrench (don't use the kickstart) will give a much more accurate measurenent. The clay mold is a LOT more work and the plasticity can lead to false measurements. If you were getting into razor thin clearances to get the absolute last ounce of performance (like building engines for the horsepower-crazy kart guys) you would probably use just one piece of solder at the front to simulate the piston angle under load, the front of the piston being the "thrust surface", but for Trials, two pieces, front to back, are a better "real world" way to do it. Michael is a gearhead like me and knows that you can get real nutty when it comes to combustion chamber design. When building roadrace engines, I'll be concerned with things like calculating "MSV" (Maximum Squish Velocity) and juggling the clearance, piston/head angles, blending radius, blah, blah, blah to get performance gains, but a Trials engine to be used by regular riders is a much more forgiving powerplant. Jon

Good advice. I've found this a problem on a lot of Trials bikes. We kickstart them probably 30-40 times a day at a Trial and the racheting mechanism can take a real beating getting slammed that many times. GasGas has an updated Pro racheting mechanism that just came out with the spiral grooves cut at an increased angle so the lever locks at a much sooner point in the arc. The gear and shaft are sold as a matched set, part # MT280226002R. TrialsPartsUSA website has some good info (including tips on the gear/shaft installation) at: http://www.trialspartsusa.com/diagrams/Pro...2013%202008.doc . It's also on their website under "tech" and is the updated GasGas Pro technical bulletin. Jon

That's good info to pass on, thanks. I've found that an NGK BPR5EIX gapped at .020" really helps the 50. The "rare earth" type plugs take less voltage to fire, are not fuel-fouling prone and have a slightly extended heat range. I run one in my 280 Pro at .024" with excellent results. Jon

"I have tested several different cyl. heads, and cylinders over time and definitely feel as if I am getting the best combinations narrowed down. I have been very pleased with the iron model 94 wombat cyl and the amal mk 2 carb with the old Gem reed valve, and an O3 cylinder head with no head gasket and anaerobic sealer used in place of a head gasket, applied sparingly. The silver paint thing did not work well for me, developing a combustion leak over time. (Yes the surfaces were flat lapped and torqued to 18 ft lbs.) With this combination the orange and green "Tree-Frog" runs really good and the compromise is just about right. It has schnurle loop scavenging accomplished by ports hand cut by me in the cyl running up from the intake passages to the transfer port height so they all pop open at the same time. " The Trials combustion chamber has a much wider squish band and sometimes re-machining works wonders, keeping the squish measurement to about 1mm (you could probably get away with .8mm due to the smaller bore/piston and lower RPMs). I built up and re-machined the head on my 85' TY350 to a true hemi style rather than the cone shape that is stock. It totally eliminated the famous "TY knock" and really improved the bottom end delievery. I replaced the stock 8-petal, open cage, steel reed setup with a reedcage and manifold from an 87' CR125, which is a 6-petal and has a "stuffer" in the cage (a formed insert to keep the intake charge intact) and Boyesen KX reeds. It's not such a big change to ride the TY now after being on my Pro (I fall off my TY and the Pro equally well....). The Schnurle Loop Principle is very effecient and you might want to try "progressive" port/time area changes, i.e., opening the rear boost port a few degrees before the rear transfers and the rear transfers a few degrees before the forward ports. This starts the intake loop-direction early in the cycle and helps low-RPM scavenging. I used this in the SX engines with good success and since you've got the reedvalve to work with, it's an option. Jon

"I have no data to back it up, but the old story goes that more header pipe volume improves low end. " "I hope to use a shorter inlet tract between the carb and reed, and reed to cyl. should be short as possible. The long intake is supposed to increase top end. " I've usually found that a slightly smaller diameter initial headpipe (less volume but different pressure/pulse/velocity pattern) tends to help bottom end, but this is a one-off project and as mentioned before, theory can be displaced by reality. The computer programs I use for exhaust development are only a tool that incorporates a baseline theory to get one "in the ballpark" and helps with the math, but a good ole cheap stopwatch is the final answer to if it really works or not. I wouldn't worry too much about the carb mount at this time. The intake tract on a Trials two stroke is a balancing act in a way in that a relative slightly longer tract will tend to help bottom end but a smaller volume in the crank area (which in a non-reed valve engine includes the whole intake tract) tends to also help bottom end by raising the "primary compression ratio" (ratio of the crankcase volume to swept displacement, which affects pumping pressures through the intake ports). The ratio of the combustion chamber volume at TDC to swept displacement (generally "corrected" by measurement from the top of the exhaust port) is actually the "secondary" compression ratio in a two-stroke. I think what all my psuedo-intellectual blah-blah means is that on a one-off project you need to essentially design and fabricate to fit and it can always be "adjusted" later if need be, as it usually does. I love to see people do projects like this, it's kinda like "rolling art" in a way and it's always interesting to see how they've solved the problems that normally come up in a frame/engine swap. I'll be following it's progress and very interested to see how the test rides turn out! Cheers Jon

Eiger, I think I know exactly the one you mean. It was a small machined cube with a strong short bolt with the end machined narrow and was small enough that you could mount it on the clutch cable if you wanted to. I looked all over the Internet and didn't find one so I imagine that having one machined is the best bet. Handy little boogers they were, and I bet I've got one (or two) somewhere in my old gear. Good luck. Jon

Seal replacement is fairly straightforward, I think the part number is ST950220 for the seal. You'll want to use a little Silicone grease on the outer part of the seal to install it and I like to pack the area between the seal lips with grease. Each leg takes 300 (+ or -)cc's of 5 weight fork oil. Unless you're familiar with how to re-set the top cap damping adjustment after removal from the damper rod, it's probably best to remove the cartridge/spring assembly as a unit by taking out the "base bolt" from the very bottom of the lower leg. To not damage the seal lips putting it over the upper tube, cut a small triangle off the corner of a plastic sandwich bag and put it over the tube, the seal will slide over it on to the tube easily. Jon

If Mark's dancing when the band comes, I'm bringing my camera. Those photos will fetch a high price in one of those "Brittany back in rehab! Strangles nurse with leather thong!" magazines they put next to the cash register at the grocery store. I'm really looking forward to coming down to Rock Creek to help out once things get a little settled up here. We have a club Trial this Sunday and then my calendar has an open space or two. The Texhoma riding area makes an old Northern California/Donner guy like me feel right at home. Jon

If it's the first time you've seen a Pro clutch, they can be a little scarey. The screws are 7mm 12-point and although GasGas has a special socket, you'll be able to find a "7mm, 12-point socket" at any good tool supply store. "and the level in the master cylinder would not go down at all"-this usually is a result of the adjustment screw on the lever turned in too far. Make sure that there is a little gap (maybe .01", just so you can feel it) where the lever adjustment screw meets the plunger rod that passes through the rubber boot to the M/C piston. Reverse bleeding usually is not necessary with a clutch on a Pro. There is a possibility you didn't fill the lower servo cylinder (looks like old President Lincoln's stovepipe hat, so it's sometimes referred to as a "top hat") with brake fluid before installing it on the post on the sidecover and there is some air trapped there. Usually it works itself out but sometimes, as a last resort, you may have to take the sidecover off, turn it "upside down" (servo cylinder hanging down) and pump it to clear the air up into the fitting. It does not take much air to get a spongy feel as the 9.5mm bore in the M/C does not displace much fluid. Check the adjustment screw clearance first. I've generally found that the two main causes of a "heavy" clutch are (1) clutch pack too thick (should measure about 17.5mm from top of hub bore to fingers) and (2) swollen o-ring(s) on the top hat post on the sidecover. "clutch release springs (I think - metal prong shaped things pointing in in a circle) had a bit of wear on the top 3-4 but no wear on the bottom"-you probably mean the fork-like "fingers", which will have a "line" at the top (wide part) where they move on the pressure plate, which is normal. "Also, one of them seemed stiff" not quite sure what that means, but maybe it somehow got bent? I've never heard of that happening but there's always a first time. I always like to assemble the clutch with the bike on it's side and before tightening the clutch plate screws, pull up on all of them to be sure they are "free" and everything is "centered" before tightening the pressure plate down. Check that lever adjustment screw clearance first and let us know if it makes any difference. Cheers Jon

It's probably a Dellorto PHBL26, which has a fuel screw. If you looks at the side of the carb body, you'll see two adjustment screws, one in the center of the carb body and one to it's left. The screw in the center sets the idle speed. The one on it's left is the pilot circuit fine-tune screw and you'll probably want to adjust that one to start with. After warming up the engine, quickly open and close the throttle and turn that screw in or out until you get the best throttle response. You'll also probably then want to adjust the center (idle speed) screw in a slight amount as the Pro's generally work better with a slightly higher idle to keep from stalling easily. Cheers. Jon

The linkage is the same for the TXT and Pro essentially. There is a copy of the GasGas USA video that U.S. riders get with each bike: http://d-mis-web.ana.bris.ac.uk/personal/H...f/media/gasgas/ and some fine soul put it on the web for all to see (my thanks again for that, I send a lot of riders to that site) so that should give you a good idea of how to re-assemble it. Cheers. Jon

I just happened to come across this thread. Hebo makes a higher taper aftermarket bar that I've been running for several years on my bike. I'm guessing it's about 1" higher and the part number is HR3000928P. I've got an 02' Pro and switched to taper bars but didn't like the newer bars that were too low for comfort and put too much weight on the front end. If you put risers on and still need some more height, you might check into these. Cheers. Jon

300cc's of 5 weight fork oil per leg. If you have problems with bottoming, you can add a little more to raise the fork oil level. Oil level has an effect on the last third of fork travel, but you may want to add some preload to the forks to start with with bottoming out symptoms. Jon

This approximation might help: Foot pounds /Newton Meters Front Wheel Axle_______________ 30 to 37/ 40 to 50 Chassis to swingarm fastener_____ 44 to 52/ 60 to 70 Upper shock absorber fastener____ 30 to 37/ 40 to 50 Lower shock absorber fastener____ 30 to 37/ 40 to 50 Handlebars___________________ 13 to 18 /18 to 25 Hand levers___________________ 5 to 7 /7 to 10 Radiator fasteners______________ 13 to 18 /7 to 10 Front bridge wing_______________ 5 to 7 /7 to 10 Brake pedal___________________ 20 to 24 /27 to 32 Muffler fasteners_______________ 13 to 18 /18 to 25 Rear wheel axle________________ 30 to 37 /40 to 50 Rear brake caliper fastener_______ 20 to 24 /27 to 32 Front brake caliper fastener_______ 20 to 24 /27 to 32 Exhaust pipe elbow fastener______ 20 to 24 /27 to 32 Engine fasteners________________ 13 to 18 /18 to 25 Rear brake pump fastener________ 5 to 7 /7 to 10 Spark plug_____________________ 8 to 9 /11 to 12 Ignition fasteners_______________ 5 to 7/ 7 to 8 Clutch fasteners________________ 5 to 7 /7 to 8 Cylinder stud bolt fasteners_______ 18 to 20 /25 to 26 Reed fasteners_________________ 5 to 7/ 7 to 8 Clutch ground fastener___________ 2 to 3 /3 to 4 Crankcases fasteners____________ 5 to 6 /7 to 8 Water pump cap fastener_________ 5 to 6 /7 to 8 Clutch cap fasteners_____________ 5 to 6 /7 to 8 Flywheel fastener_______________ 30 to 32 /40 to 42 Water fastener_________________ 7 to 8 /10 to 12 Ignition cap___________________ 5 to 6 /7 to 8 Engine drain plug_______________ 9 to 10 /12 to 14 Kickstart pedal screw____________ 9 to 10 /12 to 14 Shift pedal screw_______________ 5 to 6 /7 to 8 Cylinder head screws____________ 8 to 10 /11 to 14 Cylinder nut___________________ 18 to 20 /25 to 27 The descriptions are from the manual, so the translation is close. Cheers. Jon

Unscrew the shaft out (left-hand thread) and use a little heat on the housing to break the bond on the outside of the seal. You can usually then press the seal out carefully from the outside bushing hole with a long 1/4" socket on the impellor or pry the seal out the back with a large screwdriver. Heat generally does a good job (when you can use it without damaging adjacent parts) of releasing seals and I use it a lot in suspension work. Be sure to lube the seal around the outside when installing and after pressing it in so it clears the top of the bore, put in the circlip in and use the circlip (tapping it in with a small drift) to push it the rest of the way until the circlip snaps into the groove. The seal can be installed too far into the bore so that the impellor rubs against it and using the circlip method prevents this. Jon

Paul, Check the site: http://www.trialspartsusa.com/tech.html and you'll find the 2001 TXT parts manual etc., and a lot of other stuff that will help. Jon

I agree. I've never heard of bent valves due to water ingestion. It's possible in some older engines to cause rod, piston or possibly kickstart damage with a hydraulic'ed cylinder, but rare in today's machinery (usually the only way to bend the valve is if it's open, which would allow the water to escape, therefore no built up chamber pressure). Don't forget to drain and add new, fresh petrol to the tank. Not quite sure what it would do to the electronics, but you would imagine those to be relatively waterproof. Jon

Left-hand thread. Be sure to check the shaft for any significant grooves where the seal lips rode and if you find any, replace the shaft. The seal will last a lot longer. Cheers. Jon