jse

I think you're right. The VM Mikuni pilots in the lower numbers run in half sizes so you can usually get the pilot circuit spot on, and they also seem to have a fairly wide range of adjustment with the fuel screw due to the pilot circuit design so I would guess the Boyesens wouldn't need a pilot change, just a fuel screw adjustment. Jon

Me too, I never had to change jet sizes when I switched to Boyesens either (which I have in all my bikes). Usually a fuel/air screw change did it. I forgot to mention my observations on where the fuel/air screw were for a Gas Gas, with the carb screws on the left side of the carb. The advice as to which side (airbox or carb boot) should be accurate, wherever the carb is located. According to the profile, it's a Beta with a Mikuni carb, and I don't think he'll need to change jets unless his jetting if off to start with. Jon

Any setting for a fuel or air screw is really just a starting point to fine-tune the idle and off-idle response and varies with each engine and ambient weather conditions. Probably start at 2.5 turns from lightly bottomed out and (with a warmed up engine) quickly blip the throttle on/off and turn it in or out to get the best response. Remember a fuel screw goes out to richen the mixture and an air screw goes in to richen the mixture. Looking at the side of the carb, a fuel screw will be on the left side of the idle speed adjustment screw in the center of the carb body (near the manifold) and an air screw will be on the right (on the airbox boot side). Jon

You generally don't need to reverse pressure bleed the clutch. My guess is that the adjustment screw on the lever is too far in and the system is closed off. Make sure the piston in the master cylinder comes all the way back to the stop at the circlip (under the rubber boot). Sometimes, on a bike this age, the piston return spring in the master cylinder will sack enough to not push the piston back to it's stop and you might want to check that and possibly replace it. Jon

Iris makes a "1/2" link (3 rollers, RXL, part #BT280310067), but I don't know if the width between links and inner bushing diameter is the same as the R1. Sometimes aftermarket rear axle snail cam adjusters are oversize and allow more leeway in chain adjustment in order to preclude the need for a half-link. Jon

For those on the forum that were unaware, last November, Debbie Evans-Leavitt was injured in an on-the-set accident. I got Lane's permission to forward this to keep the Trials community advised on her progress: "HI Jon; Yes, she had a head on while riding a motor scooter with a car on the new Jim Carry movie. She was knocked out, broke her hand, wrist and pelvis and received a 2nd degree burn from the header pipe. That was on Nov. 9th. It was supposed to be a near miss, however the car came in much deeper than it had on the other takes and she smashed the door of the car in with her body. She is doing amazingly well, she is walking without a crutch short distances and is feeling stronger every day. She's even getting her fighting spirit back and is looking fore ward to getting back behind the wheel again to do some driving stunts again. I thought that she might be done after this one, because she was lucky to be alive after this wreck. However she is convinced she will make a comeback and is getting stronger everyday. Take care. Lane"

Tom, The 03' Pro usually is a 11/42 sprocket setup (I think some of the new Pro's come with 11/41's). You can also probably get one of the new thin-plate X-ring chains that will have little drag, will fit through the chain tensioner block and will transmit power, over time, more efficently than a standard chain. There are various theories on chains from (A) buy cheap standard and replace often, to (Z) buy big wide expensive o-ring and hog out the tensioner block to fit, so choose what appeals to you. I can't remember what brand the X-ring was I looked at, but I brought a short length of the stock Iris GasGas chain to compare and it was essentially the same width, but expensive. I'll try to get down to the dealer and have one of the parts guys look again for me and let you know what I find. Jon

The SilentSport packing is great stuff and I've used it ever since it came out. The standard sheet packing works well for round silencers but just about all Trials silencers are oval, so you can't just wrap it around the core and stuff it back in. SilentSport is in a bag and loose so it's easy to poke into the oval can (the center perforated core of the final muffler should be taken out and cleaned). You don't need to pack SilentSport very tight like the sheet packing, in fact they recommend you don't. Before SilentSport came out, packing an oval Trials muffler with sheet packing rated up there with changing tubeless tires in the mud for me, now, not so bad. Jon

I would tend to agree with that. I've respoked wheels for 40+ years, and there are a lot of little tricks and concerns you would need to keep track of to do a good job. It's a lot easier for an expert to do the job and in the long run, probably a lot less expensive and safer for you. Of course, if it's a skill you want to learn for future use, I'd say give it a try. Expect to spend a LOT of time getting it to come out correctly and patience (lots of it) will be rewarded. If you are doing it just to save money, it will probably not be a bargain in the long run. Jon

The part numbers are GasGas and you can get them from a dealer. A slight bit of drag is normal but you want to make sure the M/C piston returns fully back to it's stop at the circlip by having a slight bit of clearance at the adjustment screw/M/C plunger. Jon

Ron, I was lucky enough to be out of the country when they held that one, otherwise I would have been swimming/sliding with the rest of those guys. I have the video of that mudfest and when I think the weather outside is too bad to hold a Trial, I watch that National for a short time, hook up the trailer and head out to ride. Jon

The parts numbers for the short levers we have over on this side of the pond are, clutch:#BT280222040R and brake:#BT279222045. Jon

Go to the GasGas Spain website: http://www.gasgasmotos.es/ and you'll get the frame parts list, engine parts list and owner's manual available for download. Cheers and ning

I'd have Adam's factory outdoor bike, as long as he came with it to show me how to keep from splattering myself on every tree and rock in sight.... Jon

I herd dat! Jon

O.k., here we go: "VTRGG"=International manufactuers code, "GG" is GasGas, Trials type "27"=270 model "98"=model year "01"=month of manufacture "98"=year of manufacture "0884"=sequential number off the assembly line So, you have a 1998 270, built in January of 1998 and was the 884th one built. First, I would advise to never force any adjustment on a bike. If you need to force it, something needs work. You'll need to disassemble the top cap and lube the internal screw adjustment and possibly replace the o-ring. The "E" stands for "extensio'n" (spanish) or "estensione" (italian), which is "extension" in English, but most of us refer to it as "rebound". Cheers. Jon

Trials bikes will be allowed, they will just have their own class. Jon

You'll have great throttle response and then it'll fall on it's face very quickly and refuse to rev. The area in the headpipe in a two-stroke from the edge of the piston out about 6 to 8 inches (and especially the first 4 inches) is very critical to how it runs. The KX and a Trials bike engines are quite different in this area. For instance (depending on the year KX) the KX has a power valve system consisting of a flapper valve, two rotating sub-port valves and a resonance chamber that directly affect the exhaust port volume, area and timing. A Trials engine doesn't use any of this, which is why the exhaust systems are designed to do much different things depending ion the use of the engine. Jon

Hi I have just got my first GasGas, I have only ever had one trials bike before , which was 13 years ago and it was a suzuki beamish so please bear with me if i dont kno the correct terms for things. I am more a pedal power guy but just moved to the Welsh Valleys do though i would give it a crack. I was just wondering if anyone could tell me anything about the bike as some one said the forks werent standard, and to be honest the dont seem to rebound all the way back and are quite soft. Is there any way of adjusting the compression and rebound, or should i just get them serviced. I know its not a Pro but seemd a good bike to start out on as i have heard they are bullet proof. Any info much appreciated ! Looks like a 98 or a 99 model. I think the 97's were the last of the Ti Nitride coating on the tubes and they went to a Boron based coating in 98, at least in the U.S. models. What's the VIN number on the headstock (behind the headlight)? It will start with "**VTRGG". I'll be able to tell you what model the frame is and we can figure if the three-piece lower leg is stock. Jon

Hey JT! I'll be sure to tell him next time our paths cross. Here's an addition to Bikespace's post about the ambulance guys surprise seeing the loose leg: When I first went to Chris's ranch to help him set up his first Trials there we were roaring through the wooded area and headed on a steep downhill to the creek. Trying to keep up with him on our loop was a big chore and despite the loss of a leg and some fingers, that guy can fly on a bike and I used to race flat track so I can step it up when I have to and it took just about all I had. I was following him trying to keep up, headed down the steep, rocky trail when all of a sudden a riderless leg comes flying by me, causing me to promptly hit a tree at the bottom on the hill. His prothesis had come undone and I was able to dodge it, but at great cost to my delicate psyche. Needless to say, we had a good laugh...... Jon

"Has anybody checked out on a dyno the difference between low octane fuels and high ones on a trials engine? I heard of an incident at the Goodwood Festival a couple of years ago with BP when they tested two Saabs on a rolling road and the lower octane fuel made more bhp on a standard Vauhall 9-3 turbo... Oh sorry Saab 9-3 turbo Something to do with ethanol being used to get RON up but having less enegy than petrol.... anyway they swapped the cars over on the dyno's, then the fuel in the cars and found out the lower RON fuel made more peak power on these Vauxhall Vectras... erm Saab 9-3 turbos So unless the ethanol os really required to stop the engine 'knocking' its borrix off then I wonder if there is an element of p155ing into the wind by going for high RON tesco pump 99 (I'll have a 99 with the two flakes please plus a bit of diesel and other unidentified fluids... thanks!. Any Raspberry Sauce?)" I agree, the high-octane vs. low-octane fuel in Trials engines whirlwind can be really confusing. I can see where the Saab Turbo runoffs yielded those results as the octane vs hp output is like comparing apples vs oranges. The use of ethanol would possibly up the RON-research octane number- (although MON- motor octane number- is a better comparison as the testing uses more "severe" ambient conditions) alcohol has less energy per pound than gasoline. I'm not sure that the Saab engine management system can fully compensate in order to make use of the alcohol/gasoline mix to fully yield it's potential. The only reason that alcohol make high hp numbers in race engines specifically designed to use it, is that you can run a ton of it through an engine due to it stochiometric ratio i.e. you need less oxygen to get a complete burn. Essentially, one of the main reasons to use a high octane fuel is that it allows one to use power producing modifications that otherwise would result in engine damaging detonation. I always recommend that a rider use a slightly higher octane rating than his/her engine actually "needs" because actual octane requirement in an engine is not a static figure and can vary according to things like ambient weather conditions affecting jetting and mud on the radiator fins affecting cooling system effeciency, for instance. Another "octane effect" (slower burning properties) is that higher octane fuel affects the IMEP (all other conditions, like jetting, being equal), "Indicated Mean Effective Pressure", and I run 110 race fuel in my 280 Pro to soften the initial "hit" and smooth out the bottom end response without having to slot the Hall Effect sensor (magnetic pickup sensor that triggers the CDI) and retard the static timing (my Pro does not have the variable timing maps of the later ones). Jon To paraphrase a line from the movie, Apocalypse Now, "I love the smell of Nitromethane in the morning. It smells like victory"

I'm assuming that you're asking two questions: (1) what's the possible cause of the popping on off-throttle and (2) what should you look at in order to make sure it's not going to break something in the future. The first question seems to be an off-throttle lean condition, which may be a jetting problem, and if you are near sea level, here's a ballpark jetting map to start with (each engine is different, so this is only a guide and you'll want to check float level also): MAIN: 118 (115 OK, NOTHING SMALLER!) PILOT: 36 (38 OK) NEEDLE: D36 (3rd, or 2nd CLIP POSITION DOWN FROM TOP) FUEL SCREW: 3.5 TURNS OUT The other thing I'd check is for is an air leak, usually in the manifold area, the most common cause is overtightening the manifold, causing the area between the capscrews to bow out. I like to use sealer between the holes where the screws go when installing the gaskets and especially the manifold. Sometimes soapy water sprayed on the various areas when the engine is running will bubble up at the air leak site. With the manifold off, it's a good time to check the reeds for breakage or "bowing" (not laying flat on the sealing area of the cage). In a tight spot, you can sometimes reverse the reeds (turn them over to get them to seal better) to get you through an event, but that is usually only a temporary fix as a "stress riser" was created where the reed was secured to the reedblock, usually resulting in failure in a short time. The second question's answer is: when buying a used bike, if you want to avoid future problems, don't assume anything has been properly taken care of. You'll want to repack all the bearings, especially the suspension, steering and wheel bearings. I'd get out the owner's manual and renew all the fluids you can. You want to get a baseline for future maintenance and the only way to do that is to make sure everything is in good shape to start with. Jon

Generally I've noticed no harm in changing from one to the other, providing they are major brand types. I usually recommend the full-synthetic oil as they tend to burn cleaner and I've measured less wear after engine teardowns. I'm using Castrol TTS currently and all indications are that it is working very well. When I lived in California, I used Rock Oil and really liked it but it's unavailable here in the Midwest. The "semi" synthetics are a blend and there's no indication exactly how much of the formula is synthetic, theoretically it could be 99% mineral and 1% synthetic. Jon

Very good advice. You also might want to check the alternator sidecover as the cold water probably created a vacuum and sucked water into the flywheel area if the sealing surface was compromised at all. This is especially critical is it's a 2002 Pro as the cases are Magnesium (03' on up are aluminum except for the Ragas) and prone to corrosion if not kept dry. Jon