|Rider Magazine:XS11 Handling Mods - May 1982|
How to make the Yamaha XS11 Handle
A few basic modifications can rid your Excess Eleven of its characteristic wallow
NOTICE: This article was written in the early 1980s. While the diagnosis of the handling problems associated with Yamaha XS Eleven motorcycles is still accurate, the prescription for the cure is obsolete. At the end of this article, I will post a summary of current solutions (as of May 1998) to these problems.
This article is third in a series on modification of specific motorcycle models for improved riding and handling. First article in the series, devoted to the BMW, appeared in the February issue, and the second, on the Honda Gold Wing/Interstate, appeared in the March issue.
Most Yamaha XS11s will occasionally cause their riders to start looking for the hinge in the frame if they are ridden hard or loaded heavily for touring. The XS has a characteristic wallow/wobble that will descend without warning, and at the worst possible time--when one is going into a corner with too much speed. This is not a reference to the road racer; most of us have found ourselves going into a corner faster than is really safe. Usually throttling down and perhaps tapping the rear brake will get one through with nothing more than a raised heart rate. What we don't need under such circumstances is a bike that suddenly decides it would like to dance!
Most have attributed the weave or slight wobble to the weight of the bike and to its shaft drive. Not true. The XS11 can be made to handle as well as the best of today's bikes and its ride can easily be improved--even though it is already good.
If you are the owner of an XS11 and have never had the bike act up a bit, you are indeed fortunate. While giving a seminar at the Vetter Rally in the summer of 1981, I asked the dozen XS11 owners in the crowd how many of them had not experienced wobbles with their bikes. Only one person replied he had not.
A few years back, a couple of bikes wobbled badly and the cure started with remanufacturing the frame. The XS1l's problems are not of this magnitude. A couple of simple modifications and some new suspension components will dramatically improve the XS11. These modifications will improve the ride, vastly improve handling, give the big Yamaha more load-carrying capacity without bottoming, and generally make you feel at ease while riding. Even if you have never experienced a solitary twitch with your XS, these changes are worthwhile because they make the bike better.
The big Yamaha's frame is very stiff--certainly stiff enough for any conceivable street use. The slight but persistent tendency to wallow and wobble is due entirely to poor choice in damping rates and an overly flexible front fork.
Suspension changes have been made by Yamaha over the past five years since the introduction of the XS11 . These changes include a new leading axle fork, air caps and front fork damper modifications, plus rear damper changes.
While most of these changes have helped the bike become more adjustable and civilized, all the modifications needed to thoroughly subdue its less desirable behavior have not been incorporated by the factory.
The modifications we recommend are the result of considerable experimentation; they will get you a lot of performance improvement for the amount of work you will have to do and the money you will spend. You should have a factory shop manual for the torque specifications it contains; besides, you will find the exploded views very useful when you work on the bike. Grab your tools and let's do it.
Yamaha has done an excellent job of selecting spring rates for the rear of the XS11. The spring's initial rate is 120 pounds per inch. The second rate (160 inch-pounds) starts after the first 2.2 inches of spring travel. This two-rate spring enables the rear suspension to carry large loads without excessive bottoming, or it would if the rear shock had enough travel. Not only are the rear dampers too short on travel but they have an imbalance between compression and rebound damping. They do not provide enough resistance to high-velocity upward wheel travel and too much resistance as the wheel returns to its normal position after striking a bump. By installing the stock springs on a set of aftermarket dampers, you can improve the handling, ride and total load capacity of your bike's rear suspension.
We have tried all the accessory dampers available for the XS11 (and some that aren't out yet). We found two that do the job best on the XS11: the Fox Street Shox and the new S&W Pro-Strokers. The Fox dampers will accept the stock springs. S&W's Pro-Strokers require their own two-rate springs and S&W has designed a new spring for the XS11. It is a 125-165 inch-pound spring and will carry slightly more weight than the stock spring without bottoming. Either damper is of high quality. They are truly rebuildable and will give very superior performance when compared to the stock items.
If you don't mind denting the left muffler a bit to clear the axle, I recommend you install 13-inch rear dampers rather than the stock 12.5-inch units. One of the problems of the stock bike is rear suspension that does not have enough travel to allow the low spring preloads so important to ride quality and bumpy-road traction. Yamaha increased the spring's preload so the XS11 would not bottom too often with the three-inch travel rear dampers. This tends to make the bike hop over rough roads, be excessively reactive to the torque input of the shaft drive, and helps "pump" the bike's suspension while cornering with the throttle shut off (as most of us do).
The longer damper will have more travel (the Fox has the most) and permits less preload and less bottoming. The length of the 13- inch shock allows lower spring preload without sacrificing ground clearance; it also results in a better ride. The longer stroke of the 13-inch shocks requires that the springs be compressed farther before the suspension is bottomed, thus allowing a greater load capacity and smoother ride. If you select the S&Ws, ask for the lowest compression damping and the heaviest rebound damping. Fox Shox work best on the XS if the damping selected is firm.
Earlier, I referred to denting the left-hand muffler when 13-inch dampers are installed. A little work with a ball peen hammer will do the job nicely. You won't have to move much metal, and so far there have been no adverse effects from doing this.
Fox also makes a 12.65-inch damper that will do, but it has less travel. You may not care about the greater load capacity of the longer units and I feel that they are not necessary--just better.
The XS11's front fork lacks torsional stiffness--something it shares with most bikes that do not clamp the front axle on both sides. The most important factor in front fork stiffness is how well the front axle is clamped. Of course, the XS11's axle is clamped only on one side. When new, friction between the fork leg and the axle will hold it pretty well. After a few thousand miles, however, the axle polishes the hole it fits into and the fork assembly will begin to move around. This is one of the reasons wobble problems tend to show up after several thousand miles. The answer is a fork brace.
Yamaha's steel front fender really isn't very stiff and contributes only a little to the rigidity of the fork legs. I have installed three brands of fork braces on various bikes and feel the one made by Racer's World is the best. It is very stiff, has a fine, tough finish and is easy to clean. Another brand uses sheet steel to connect the steel tubing braces. it works okay, but the sheet steel makes it rather difficult to clean the space between the brace and the fender. It also costs more than the Racer's World brace.
Variations in motorcycles make it impossible for the manufacturer to guarantee that the brace will fit perfectly. If the brace does not precisely meet the fork's fender mounting lugs, the fork assembly will bind and stick when the fender bolts are tightened. You should remove the front wheel, calipers and fender. Fit the brace to the fork and see how well it lines up. Normally, you will have to remove material from the fender mounting lugs so the brace will be a slip fit between the legs. The best way to do this is to carefully file the bolt face of the fender lug with a large flat file. It isn't difficult to do and, if the file is a rather fine one, you will not remove material so fast you can get into trouble. File the fork lugs until the brace will fit into place without causing a side load on the fork legs. Spend some time with this and do it right. Bend the fender until it fits between the lugs of the fork brace without any bind. In bending the fender to fit within the brace, you will see just how weak it is. When you finish fitting the brace, you are halfway through with the fork modifications.
Air Caps and Fork Springs
Yamaha, again, did an excellent job of selecting spring rates. If you have one of the 1978-79 XS11s, you should fit air caps; if your bike already has them (from the factory) you will still need to modify the spring preload and install an equal air fill kit. We used the Goki EF-102 kit from Racecrafters; just make sure the threads on the air valve are either 8mm or 10mm and stipulate which they are when ordering. First, let's deal with forks without air caps.
Although the stock springs of the air-less XS11s are correct for this use, they are too hard for use with air. I have been using a set of springs from S&W designed for the Kawasaki Z-1. After trimming, these springs have an initial rate of 34 inch-pounds and a final rate of 54.
After you have selected the air caps you want to use (I haven't seen any bad ones), remove the stock fork caps and springs. You should block the front of the bike up for this. Fit an S&W spring into one of the fork tubes and place the air cap on top of it. Now, measure the distance from the top of the fork tube to the seat of the air cap. Make this measurement with fork fully extended; the desired measurement is .7 inches-you will probably find that it is more like 1.5 or more inches. Trim the spring until screwing the air cap in all the way will require .7 inches of spring compression-this is the preload.
A good way to shorten the fork spring is to file a deep notch in the spring and then break it off with a pair of pliers. If you have access to a bench grinder, cut the spring three-quarters of a turn longer than the desired length and grind the end flat on the grinder. This will give the spring the flat end it had before being cut. If you do not have a grinder, cut the spring in the same place, heat the last half-turn over a gas flame until it is glowing orange, and then push this end against a metal block to collapse the heated portion. Since the end is now soft, you may use a file to flatten the end. Stock air-cap springs have a proper rate for air forks and simply need to be shortened so the total preload is .7 inches as described.
Some of you will have heavy fairings mounted on your bikes; if you do, increase the specified preload by one-eighth inch for every 10 pounds of fairing. For instance, if your fairing weighs 40 pounds, you will need 1.2 inches of preload instead of .7 inches.
After you have sized the fork springs, set them aside and remove the damper rod assemblies from the fork tubes. Yamaha holds the damper rods into the fork legs with an 8mm Allen bolt that sits in the bottom of the fork leg. You will need an 8mm hex key and a special tool made from a bolt and two nuts. The top of the damper rod looks like the inside of a socket and it is. A 19mm (across the flats) bolt will fit this recess in the damper rod.
Purchase a bolt that fits a 19mm socket and a couple of similarly sized nuts. Thread both nuts onto the bolt and tighten them against one another. Fit the assembly into a socket and tape them in place. Now, with all the extensions you have, run the "special tool" down into the fork tube until the bolt head engages the damper rod. This will let you hold the damper rod against turning as you unscrew the bolt. Yamaha uses Loc-Tite to secure the bolt so it will be hard to turn for the first couple of pitches. Remove the bolt (don't lose the copper sealing washer under its head), remove the fork leg and push the damper rod out the top.
Inspect the damper rod. You will find a small hole near the top of the rod. There will also be two or four larger holes near the bottom. The top hole controls rebound damping while the lower holes determine compression damping.
Drill through the top hole with a number 52 drill, continuing through the hole in the opposite side of the rod. You will have two number 52 holes in the top of the rod. Some of the latest air-fork assemblies have one larger hole in the top of the rod. You should drill a second hole anyway. If you can't find a number 52 drill, use a 51 or a 53--it doesn't seem to be terribly critical.
Drill the bottom holes with a .200-inch drill (plus or minus .010.) If your bike's damper rod has two holes, ream them out with the .200 drill, then drill two more at 90 degrees from the first so the rod has four .200-inch diameter holes near the bottom. Those rods with four holes need merely to have the existing holes reamed out with the drill.
Deburr the holes thoroughly and reassemble the fork. There is an anti bottoming piston in the bottom of the fork leg. It probably stuck to the leg when you pushed the damper rod out; be sure it is in place as you reassemble the fork. Tighten the damper rod retaining bolt to factory specs. I have never used Loc-Tite and have never had a problem.
Fork Oil Volume
An air fork has two springs: the coil spring and an air spring. For the air spring to work property, the free-volume of the fork must be critically controlled. We will increase the amount of oil in the XS11's fork to increase the progressivity of its air spring. This more progressive air spring will control dive during braking and give the bike better antibottoming control.
Collapse the fork completely (bottomed) and pour in Kal-Gard 10W fork oil until it is 5.7 inches from the top of the fork tube. Be sure to pump all the air out of the damping chambers before you top-off the oil level. It is very important that you adjust the oil level carefully; small changes in air volume will have a large effect upon the air spring effect.
Do not use heavier oil; you didn't drill those holes just to defeat their purpose. I strongly recommend Kal-Gard oil. It is filled with MoS2 and you will notice an improvement in fork smoothness.
Reassemble the fork, brace, fender and wheel. Be sure to take the time to thoroughly check over all that you have done and be sure that all the bolts are tightened.
Try 10 pounds of air in the fork as a starting place. Most of the XS11s I have modified seem to work best at between seven and 15 psi.
For the fun of it, I recommend that you do all the work at one time, fitting the brace and modifying the rear and the front dampers. When you ride the bike for the first time after the changes, you will be really surprised! Your XS11 will ride better and you will have more control than you might have thought possible. No one has reported any negative side effects due to these modifications. They simply work. Happy motoring!
Current solutions to XS Eleven handling problems
Let's start in the front. The forks really do need a fork brace. The companies listed above either don't exist anymore or stopped selling anything for the XS Eleven a long time ago. These days, you have three options.
The first option is to call around to the different boneyards and see if any of them have a used fork brace. They don't typically wear out - although some of the steel ones might have gotten rusty. It's hard to say what your price will be. It could conceivably be as much as $100USD. Or it could be a lot less. It all depends on the boneyard and how much you're willing to spend. You'll also have to take the word of the guy at the boneyard that it really is a forkbrace for an XS Eleven.
The second option is called Telefix and there's a tips page with detailed instructions on how to install one. It's a perfectly good fork brace, made in Germany, I believe. Cost is around $130 - 140. It definitely works, but it's a bit pricy and doesn't add much to the styling of your bike.
The third option - and possibly the best option - is something made by one of our own. R.C. Laton, aka Tkat listened when I said I was mildly disappointed with my fork brace. I sent him what I currently had, along with some ideas on how I thought it could be made better. Tkat took those ideas along with some good old-fashioned machinists' know-how and came up with the Tkat Fork Brace. He is selling these to us at a ridiculously low price. He says he's not doing this to make money. With what it takes to make one of these, he's not going to make any money. This is truly a labor of love.
But the fork brace won't solve all of the front end problems. For that, you need new fork springs. Above, the author spoke of taking fork springs from a Kawasaki Z-1 and cutting and grinding them, etc. Well, Z-1 parts are probably less available now than XS Eleven parts. Fortunately, Progressive makes a progressively wound fork spring for the XS Eleven. No cutting, grinding, or any of that other nonsense. The same spring is for either the standard or Special model. If you have a Special, you will have to go down to your local building supply store and purchase a piece of 3/4" schedule 40 PVC pipe. Mine cost about a dollar for 10 feet. You'll need to cut two 3 1/2" pieces (one for each fork tube). Because the axle goes through the fork slider on the standard models, unlike the Specials, the standard models do not need this PVC spacer. The cost of these springs is about $60-70 USD and can be found at your local dealer or mail order companies such as Dennis Kirk.
On my bike, a 79 Special with a full Pichler fairing, I have found that with the Progressive fork springs, I do not need any air pressure in the forks. Zero. With the stock fork springs, I used to run with 29 psi. (When I had stock springs, I added an equalization system with a small pressure gauge attached.) When I first put the Progressive springs in, I did try running with pressure in the forks and I found the ride way too stiff and harsh. I suspect that if you don't have air caps already on your bike, when you get Progressive springs you won't have any need for them. If you do have air caps already, you'll probably do just as well to release all of the pressure and not use that feature anymore.
That should take care of the front of the bike. Now on to the back.
As was stated above and in other articles (especially about the Specials) the original shocks were pretty darn good. They might even be called state-of-the-art in historical context. But that was about 20 years ago. Unfortunately, like with the fork braces, the companies listed in the article above either are gone or don't sell the parts you need. However, there are still some options.
Progressive (yes, the same ones who make the fork springs) makes a couple different shocks that work very well for our XS Elevens. They come in two price ranges. Expensive, and more expensive. This is definitely a case of you get what you pay for.
I would not recommend Progressives' air shocks. I had put a pair on my 80 SG and was very disappointed with them. To start with, they were rather expensive. That alone shouldn't deter you. One thing that I was very frustrated about is that the right shock was cosmetically damaged by the bracket that holds the brake line. Because the air shocks are larger in diameter than the stock shocks, there was a minor amount of physical contact between the bracket and the shock. This contact caused a fair amount of abrasion to both the shock and the bracket is a relatively short time. This could have been prevented if there had been some sort of warning in the instructions. The solution was simple - bend the bracket in slightly (about 1/4 inch) so that it no longer came near the shock. but by the time you realize that it must be done, the damage has occurred.
The second problem I had with the air shocks was that it was difficult to achieve a comfortable ride. I suspect that there's a very narrow psi range that gives good comfort. I couldn't tell you what it is.
The last problem I had with the air shocks is when a seal blew, leaving me with a hardtail Special on a 200 mile ride to a rally with my wife. When we got home, I checked into a repair kit for the shocks and I was flabbergasted to learn that the repair kit was about what I paid for the shocks. That left such a bad taste in my mouth that I decided to not to bother repairing them. They found their way into the garbage can and I put the old stock shocks back on.
But Progressive isn't the only game in town either. Another XS Eleven owner put shocks from a V-Max on this XS and was pleased with the results. I believe that was James Ho and I also think he said it also served to lower the bike a bit as well. You should be warned, though, James is one of the (physically) smaller and lighter folks on the list. Some of you heavyweights may find that this setup bottoms out under your additional poundage.
I think the best course of action to fix your handling problems is to get a Tkat fork brace, Progressive fork springs, and the better Progressive adjustable shocks. All together it might cost you about $400-500 USD but when you consider that it will give you incredible handling (the phrase, "handles like I was on rails," comes up a lot - even after just doing the front end work). Just the front end work will cost you about $130 if you do the labor yourself. To quote an old friend, it's only about a 12 bolt job. Heck, if I could do it, just about anyone can.