I could use some help from a Canadian source. My 1999 Kawasaki 1500 Vulcan Drifter has a
Dana, your 99 Vulcan Drifter, if it is a Canadian model, can be beefed up quite easily; allowing you to keep both arms and legs. The rear shocks are a coil spring / air spring hybrid that is actually quite adjustable. This model was shipped from the factory with the rear air ŌpreloadÕ set to atmospheric pressure as standard. The two shocks can be pressurized all the way up to 43 psi, which would cover the range right from a light rider all the way to two up, fully loaded with luggage. The folks at Kawasaki suggest starting around 15 psi if you feel your ride is too soft, and going up if needed from there. The tricky part is in the details. You cannot head off to the gas station and use the pump there for an accurate job. Even if you over pressure the system and use a tire gauge to bring the pressure down to where you want it, you wonÕt accurately hit your pressure target. When checking the pressure of any pneumatic device with a pressure gauge you lose a small volume of air each time you attach your pressure gauge to the Schrader valve. Some air leaks out to atmosphere, and the rest charges up the hose and into the tube inside the gauge itself. When you are checking something with a very large air volume like a tire, this lost air is no big deal, working out to be about a ¼ psi or so. However, when the device you are checking has a very small volume of air (like a shock reservoir or fork) the simple motion of checking the pressure will let out more like 10-20 psi. So, you need to either use or borrow a proper pressure-filling device. Motion Pro sells a kit for nitrogen filling shocks that has a integrated gauge, fill valve and hose with the proper Schrader valve device. You attach the fitting over your shocks valve and then wind down the toolÕs little ŌTÕ handle that pushes down on your shocks inner valve core. Then you can give a crude blast of high pressure air to the main body of the tool, bleed out the air down to your target pressure, unscrew the ŌTÕ handle and remove the tool from your shock with the pressure set perfectly. Any bike shop can get this tool for you or perhaps do this for you if they have the tool themselves.
The last caution is in the procedure for filling. You can easily imagine that on a twin shock bike like yours it is very important for both preloads to be set the same. Cruiser swingarms of that style are designed to spread the load over the two shocks that are positioned way out by the axle. They donÕt need to be as rigid as the latest crop of sport bike swingarms with single shocks that experience much higher stresses from cornering loads. So, if your preloads were out noticeably left to right, the swingarm would see a twisting force that wouldnÕt do any componentry any good, let alone the handling, stability and subsequent safety of your bike. During filling, the best way to ensure the volume doesnÕt change as you fill first one, then the other shock is to fully extend the suspension. Either lift it off the ground with a bike stand, or have someone of significant ŌballastÕ pull the bike over while on its side stand to extend the shocks. Imagine if the bike were sitting on its own weight and you pressurized one shock from 0 to 15 psi, the increased preload might lift the bike a few millimetres during the fill. Now you head off to the other side and do the same, during its fill the bike raises another 5 mm or so until you finish setting that pressure to 15psi as well. What do you think happened to the first shocks charge pressure now that the bike is sitting 5 mm higher than when you set it? Right, it went down to about 5psi with this new larger volume! So, get the bike off the ground, take your time with the proper tool, and you will be rewarded with a very nice effective change to your ride. DonÕt be alarmed if you see a little oil come out during the process as these shocks are what they call an emulsion type that donÕt have a piston or bladder separating the air from the shockÕs damping oil. The last option to be aware of is the four-position rebound adjuster on your shocks. The rebound controls the speed at which the shocks extend back after compressing over a bump. They are set to position #2 of four from the factory. If your bike wallows a few times after hitting a bump, try increasing the setting to #3 or #4. You may have to play around with the suspension a bit between air preload and rebound, but you have excellent adjustability with your stock components.
Why haven't they put the countershaft
sprocket on the swing arm pivot
Good question. Ducati, and now BMW, is the only mass producer I know of that goes to any great length to reduce the distance between the swingarm pivot and the countershaft sprocket. The main engineering problem is the location of the engine cases when these are lined up. The cornering loads with modern sport bikes riding on excellent tires mandate a very strong swing arm pivot. When you complicate the location of the countershaft sprocket (and in effect the whole transmission output shaft) lined up with the swing arm pivot, it is hard to do both. Then service, and initial installation at the factory during production is a costly nightmare as the swingarm either pivots through the motor somehow or Ōspans itÕ. It is just not worth it for the very slight chassis improvement only noticed when raced at 10/10ths to incorporate this into every street bike built, as the typical street rider will never appreciate this, and will not want to pay for
it when shopping around. The RC211VÕs pivot is quite a ways from the countershaft sprocket and it seems to work ok!
Remember to send your technical questions to John Sharrard at email@example.com