jse

As you've found out, the "off-idle to 1/4 throttle" is a very busy time for a carb. It goes from idle circuit, to pilot circuit, to needle draw, and all this is mitigated by the slide cutaway and the fine tuning of the air/fuel screw. The #'s on the slide generally correspond to the height of the cutaway, in that a #55 slide will have a cutaway height of 5.5mm. The higher the cutaway, the "leaner" the slide as it channels more airflow over the needle jet tower. I'm not sure what pilot jet you have in, generally a #36-38 works well. The pilot jet "pilots" the air/fuel ratio from idle to needle draw that would otherwise have a big gap until the air velocity/pressure drop over the needle jet reached necessary measurement. Flatslide carbs tend to channel more air over the center needle jet area rather than around it as a round slide would do. This provides better draw and throttle response. Jon

I doubt the PHBH will fit the PHBL. The PHBH is the large body, oval bore used only one year in 1996 on the JTR370. Hot temps and humidity tend to richen the air/fuel ratio (Oxygen atoms are farther apart and the water molecules tend to take up space in the volume of air available) so you might look at a pilot jet/needle position change to compensate. The less dense air will also produce a slight lag in response if winter jetting is used. I'm assuming you have already adjusted the air/fuel screw for the ambient conditions. Jon

Hi Jan, Yea, I forgot to convert it into 85.72896 kilograms for people that drive on the same side as we do (well, most of us anyway)......... Course, that's advp pounds and not troy pounds......darn, now I'm confused..... Jon

"Im 13 and half stone" I'm sure that some readers in the U.S. thought you were a very young teen bragging about smoking dope. For readers on this side of the pond, a "stone" is the same as U.S. 14 lbs and at about 189 lbs body weight,, I would think that 315cc's of 5-weight fork oil per leg should work. Jon

The race fuel will give you less "snap" due to it's slower burning properties (kinda like retarding the static timing a little, it changes the "Indicated Mean Effective Pressure" ie: there is a little less pressure buildup between when the plug fires and the piston reaches TDC). I use it in my 02' 280 Pro to smooth out the lower RPM power delivery (I'm a slow, old geezer) and it can be used by riders to adjust the power output in wet, sloppy conditions when traction is marginal (softer power delivery off-idle) and the radiator may get plugged with mud (the higher octane is a little insurance to resist detonation due to higher engine temps). Jetting on the 05' Pro (sea level) should be in the neighborhood of: MAIN: 116/118 PILOT: 36/38 NEEDLE: D36 (3rd, or 2nd CLIP POSITION DOWN FROM TOP) FUEL SCREW: 3.5 TURNS OUT TO START (adjust for ambient conditions) I run my 280 with a 118/38/2nd-clip combo with good results and never a "pink"..... Jon

Try the 2.5 weight just on the compression (left) side to see if that takes you in the direction you want (always change just one variable at a time to be able to accutately evaluate the results). The nice thing about the Marzocchi forks is that the rebound and compression is in different sides so the oil viscosity can be individually adjusted to fine tune the damping action, forks that have both damping assemblies in the same cartridge (like some forks that only use one spring) will have both compression and rebound changed by oil viscosity adjustments. The adjusters at the top are essentially "high speed" tuning adjustments (they are usually a needle valve, or in some shocks, a varible orifice, and work by allowing a variable amount of fluid to "bleed off" after a certain pressure is reached) and work with the higher damper shaft speeds (like a big hit on a rock that quickly accelerates the shaft through the cartridge). The main damping process is dictated by the "shim stack", or set of special washers on the piston that travels through the cartridge, and that is not adjustable unless you substitute a different set of washers or change the diameter of the holes in the piston (a job for a suspension pro with special equipment). I agree that fork bind is always the first place to look when dealing with suspension problems and it is usually free to fix, just taking a little time. If the adjustments do not solve the problem, it might be a good idea to disassemble the forks and inspect the bushings and upper tubes . Binding forks (sometimes caused by a bent fork tube) will wear the bushings quickly and it's difficult to tell if that has been a prior condition. Jon Quick edit note: The oil level is critical in the Marzocchi's and they really should be set by oil level rather than volume or you will often end up with too much oil (and harsh damping on the comprssion side).

To add on, this has become my favorite shop video (and the price is great). I put it in the player and can listen to the music or watch the bikes depending on what I'm working on at the time, so I'm glad I got two (my son will get a re-formatted copy as he only has NTSC) as I may wear out the first one. I understand the reason for the soundtrack, the constant rushing water might drive me a little more bonkers than I am now (which is quite a bit).......I'm totally happy with mine. Jon

Most riders find that a ratio of 70 or 80 to one of a full-synthetic premix oil seems to work well. Jon

Stuart, I have a couple of Monos and never had suspension linkage problems. The nice thing about the Mono is the Zerk fittings and when they are lubed, the grease forces out the dirt and water that may have entered, plus providing fresh grease. I have an 85' and 86' and both have the original linkage bearings, which are checked often. Jon

Two sets of crank bearings in 6 months is not normal, by any standard, except if Raga rode it maybe . I have the original set in my 02' Pro 280 and no signs of a problem. The water in the sidecover is not unusual (for any bike) if the seal is compromised. Some riders drill a small hole in the bottom of the sidecover to drain water, but this will cause the engine to suck in water through the hole if in a creek, as the sudden cooling of the case creates a vacuum (which, hopefully will drain out later). The oil in the sidecover, however, is unusual and you might look for the cause. Maybe a scratch on the sealing surface of the crank that has worn the seal or the copper washer left off the case capscrew that has an oil passage inside the hole? As for the bearing failure, you might expand the search for the cause to something beyond the bearing itself, like installation preceedure or crank misalignment, for example. Jon

Walter was 92. When in his broadcasting prime I think a TIME magazine poll found that he was "The most trusted man in America". Just think, YOU could be "The most trusted man in Scotland"!!!!!! You have my vote. Jon

Jan, Yes, one spring per leg. Sounds like the forks should take equal amounts of fluid in each leg. The slightly larger holes in one cartridge is probably the compression side, which has generally a higher piston speed that would require a little more bleed area/volume (rebound speed of the cartridge piston is usually slower than the compression side, as the compression take a big, fast hit-like a big rock- and the rebound is pushed back by stored energy in the spring). Jon

Jan, I think the 125 forks are the same as the larger models (guessing, not from experience, however) and the 270cc spec. seems right for the aluminum upper tubes (the "waisted" design of the upper tube means less of an air gap to start with so a little less oil is required). I know the 125 Marzocchi forks with the steel upper tubes take about 290cc's. The 130/230cc type measurement is generally for forks that use only one spring. I havent worked on the 125 aluminum forks but I'm assuming the 125 aluminum forks use two springs? Unless there is one spring or somehow the internal cartridges are radically different from the larger models, the oil volumes will usually be the same for both sides. Jon

Jan, If you are going to do much work on the Marzocchi forks, you might want to make a tool like the fork cartridge bleeders I made. They are tubing, about 36cm long, that a nut the size of the cartridge rod threads is brazed onto and have a bleed hole at each end (these I made cover four different sizes of rod ends). The tool is threaded on the end of the cartridge rod and is used to bleed the cartridge by pumping and also holds the rod end so it's easy to pull out to attach the rest of the components. Jon

Doh! I misread the request, gotta take some time after a week on the road before reading posts. Change the specs on the rebound side fork (right side) to 7.5 weight and 290cc's of oil. If the fork oil is black to a degree, that's the outside of the springs that have scraped off (it's normal). Be sure to clean out the bottom of the lower tube where the gunge collects. Sometimes there is enough scraped spring residue in the bottom of the leg to interfere with damping (it collects in the "shim stack" of the cartridge where the actual damping proceedure is done). Jon

The knobs at the top of the forks are essentially "high speed" tuning adjusters, not MPH of the bike, but the velocity of the shaft moving inside the internal damping cartridges, so you may not realize a big change. You can start by adding a little penetrating oil under the knob to loosen them up (they are often slightly corroded and difficult to turn in older forks) and slowly and carefully turning the knobs back and forth. The 99' forks seems to work for most riders with the compression knob (black on left) turned fully out and the rebound knob (red on the right) fully in (lightly bottomed, as in all suspension adjustments). You can change the fork oil in the right leg to 315-320cc's of 2.5 weight, which will decrease the rebound a lot. What is more than likely actually happening is that the forks are binding, which is usually more apparent in the rebound phase. Try loosening the fork and axle clamps (and remove the fork brace) except for the top two capscrews on the tripleclamp and move the forks up and down to "center" them, then tighten the lower tripleclamp to 18 ft lbs, center the forks again and tighten the axle clamp (about 7-9 ft lbs). The fork brace always goes on last. The screws should drop in the holes and thread easily, if not, use a file to enlarge the holes, don't force them in. If it's a used bike, the upper tubes may have been bent slightly, which will also cause binding, and you may want to check that out. Cheers. Jon

As it was meant. Cheers. Jon

Me too. I just got back from a week in Colorado at 3:30am and there were my DVDs waiting for me. Got a chance to watch this afternoon and I really like it. The slo-mo shots were welcome and I'm very happy with the whole format. I just ordered the CJB DVDs also, but you really need this one too to get the full flavor of the event. Good work! Jon

Andy, You may have missed the cause of the seal failure, which may likely be small pits in the upper fork tube. Use your fingernails to go over the whole surface of the tube that is exposed (not the part from the lower clamp on up or below the fork wiper, just the area where the seal lips rub). Fingernails are very sensitive to surface imperfections and you will be able to detect pits and nicks that are hardly visible to the eye. If your nails feel a scratch, that slightly raised sharp surface will quickly cut a seal lip. If you find one, use 600 grit wet/dry sandpaper on a flat piece of steel and sand around the tube at the nick spot, not just on the nick, which will cause a flat depression. As for the adjuster, take the plastic knob off and put some penetrating oil in the screw area, let it sit for a time and then carefully work the screw back and forth slowly (light pressure) to break it free. Jon

For those of you who have not heard John on camera, he's Scotland's answer to Walter Cronkite, suave, cool and very knowledgeable. Jon

Maybe. And, then again, maybe not...... Jon

Man! I gotta have that bike! I'm sure I have 300 pounds of something to give for it, probably out in the garden. Jon

I just ordered 2 also, I like the stereoscopic effect when I put both in the player at the same time....... Actually, the second one goes to my son, who is also a Trials nut. Jon

You can probably accomplish both extra rebound and more preload without taking the forks completely apart (the 99' has a removable collar so it's a little different to work with than the newer types). Remove the forks from the bike, but before starting, loosen the top tripleclamp capscrews and carefully back off the top caps a little to make them easier to remove later (the topcaps use an o-ring to seal and should only be snug, the clamping action of the top tripleclamps will make sure they do not back off any). Hold the topcap and unscrew the upper tube, collapsing it into the bottom leg and drain and flush the forks and let dry out. To change the preload bushing (it's usually a grey PVC tube on the top of the spring) pull down on the spring, which will allow the preload bushing to drop down and you'll see a jamnut under the topcap. Slide an openend wrench on that (you can release the pressure on the spring then) and then loosen the topcap a little. You'll then want to unscrew the topcap off the damper rod, but pull down on the spring a little so when the topcap seperates from the rod it does not go flying off. You'll then be able to slide off the PVC spacer. You'll want to make another spacer about 5-8mm longer to replace the one you took off (it's called "Schedule 40 PVC pipe", which has thick walls and you can get it at a hardware store) and reassemble the damper/spring assembly. The forks take 300cc's of 5-weight fork oil. Since you want a little more rebound, use a 7.5 or 10 weight fork oil in the right leg, which houses the rebound cartridge. Usually the best way to add the oil is to collapse the upper tube down, tilt the fork leg a little and slowly dribble the oil in between the spring coils. Whenever you stiffen the spring in a fork, you provide more compression resistance but reduce the rebound resistance (damping effeciency is reduced), so you may want to back the topcap compression adjuster (left fork) all the way out and screw the rebound adjuster (right fork) all the way in, and LIGHTLY bottomed out (most riders find the GasGas forks work well with the compression full off and the rebound full on). Just about all damping adjusters on any suspension components that use a needle/orifice are somewhat fragile so handle them with a light touch. Clean the insides of the tripleclamps, reassemble the tubes in the clamps (the capscrews go about 15-18 ft lbs torque, and use anti-seize on the threads). Start tightening with the top tripleclamp bolts, push on the forks to center them, tighten the lower tripleclamps bolts (alternating the bolts so as to tighten them evenly), center forks again, tighten axle, center forks, tighten axle capscrews ( only about 6-8 ft lbs and use anti-seize) and them install the fork brace last. I think that covers the high points and others will fill in the gaps. Cheers. Jon

Hi, slack. Your 05' should have the steel tube Marzocchi's and you'll want to set those forks by oil level, not volume, as the cartridges do not fully drain like the GasGas cartridges. The steel tube forks have the oil level set at 180mm, spring removed and tube collapsed into the lower leg. The Marzocchi's have a little different damping orifices than the GasGas forks and take a slightly heavier viscosity, 7.5 weight for "normal" damping and if you like them "springy" use 5 weight. You can also tune the damping on the rebound and compression seperately by oil viscosity changes. If you have any bottoming problems (rare on the Marzocchis) you can raise the oil level to, say, 170mm, which will affect fork compression rate in the last 3rd of travel. Jon