Adjusting Sag

One of the first things you will notice about the table below is that you will not find a PRELOAD section.   The reason I do this is because this needs to be the very first step in adjusting your suspension.   If it is done correctly (and you write it down) then you won't ever have to touch it again unless a) you gain or lose a lot of weight, b) you carry a passenger, or c) you change your settings for the track.   Don't rush through this step.   Very often if the preload is adjusted incorrectly it will act like a spring rate problem, ie. too much preload will act like a too stiff spring.   The correct sag for sportbikes on the street should be 30-35 mm for the front and 25-30 mm on the rear.   If you take your bike to the track, you can stiffen it a bit and reduce the sag amounts by 5 mm.

To measure the suspension's sag it is best to have you and two other people.   First, lift the rear end up until the shock is fully extended and measure the distance between the seat and rear axle in a line perpendicular to the ground.   Write this down as L1.   Then, while wearing your riding gear, sit on the bike in your normal riding position, have the first helper balance the bike and pull up slightly on the rear, then slowly letting it settle.   Have the second helper measure the distance between the same two points.   Write this value down as L2.   Now have the first helper push down slightly on the rear of the bike, then slowly let it settle.   Take the same measurement and write it down as L3.   Now perform the same steps on the front forks, using a tie-wrap or an O-ring around the inner fork tube.   Use the following to calculate the bike's sag: L1 - [(L2 + L3) / 2].   The reason you average L2 and L3 is to account for "stiction" in the seals.

To adjust the sag, turn the preload adjusters on both the forks and/or shock as necessary to obtain the desired sag amount.

Adjusting the Damping

The VTR does not come with adjustable compression damping, but the RC51 and many other bikes do.   So I will briefly go through how to set both compression and rebound.   After you have set your sag, mount the bike and quickly compress and release the front forks while holding the front brake.   Watch the fork action carefully.   The fork should come back up fairly quickly, quick enough so that forks reverse direction and settle, but not so quick that they come back up after that.   Simply put, they should come up, and slightly settle only once.   If you have too much rebound, the forks won't reverse direction.   They'll just come up and stop.   Adjust your rebound as necessary.   Okay, now that the rebound on the front is set you need to find another person for this next part.   With someone watching the bike from about 15 ft away, carefully but forcefully compress the bike at the steering head and seat, as to compress the suspension equally on both front and rear.   DON'T DROP YOUR BIKE!   Now, the rear rebound should be set so that it comes up just SLIGHTLY slower than the front.   Adjust the shock as necessary.   The rebound is now adjusted.

As for the compression damping, you really have to go out and ride the bike and determine if the bike is dealing with bumps and not rattling your teeth loose, but at the same time handles braking, acceleration, and corners well.   Make small adjustments, one or two clicks at a time.   You should know when you have it dialed in.   Use the table below to determine if you have too much or too little compression damping.

VTR Suspension Guidelines

The VTR comes from Honda with too soft progressive fork springs (.58 kg/mm) and too stiff rear shock.   One of the best upgrades you can do with the VTR is aftermarket Racetech or Ohlins fork springs (about $100) and Racetech Gold Valves ($150).   If you are mechanically inclined and have the space and tools, I urge you to do these modifications yourself.   You will 1.) make sure the job is done right, 2.) learn something about your bike in the process, and 3.) save money and time.   Order new fork seals while you're at it.   You might damage one of them when installing the Gold Valves.   The difference is amazing, though you will notice that a stock rear shock makes the front end work harder due to the lack of bump absorbtion.

The fix for the rear end is quite a bit more expensive ($566-1050) but is fairly easy to install.   I got a Fox Twin-clicker shock for a great price at the time, though the MSRP for this shock has gone up recently.   The lowest I have found is AZMotorsports (see Links) for $566.   Installation requires raising the rear of the bike using straps attached to the subframe and undoing the two bolts at the top and bottom of the shock.   Dismantle the shock linkage.   Raise and lower the rear of the bike to manipulate the swingarm and linkage as needed.   The exhaust does not need to be removed like the Honda manual states.

Notice that in the following table there can be more than one cause for each effect.   For example, fork oil level being too high has the same effect as too much compression damping.   Both cause the front wheel to skip on bumps.   Look at all the symptoms and make your best judgement.

Find a favorite road that challenges your suspension in different ways and go out and ride!   Take the tools and this guide with you in your tankbag for quick adjustments.   Remember to make small adjustments and only do one adjustment at a time.   Today's sportbikes have enough adjustability in their suspension to get you into trouble so be careful.   Have fun!

UPDATE!!!   You may find that with stiffer springs the rebound damping is insufficient.   In other words the rebound valving is being overpowered by the stiffer spring.   You can try a thicker weight oil but that will adversely affect your compression damping.   The forks will be too stiff over bumps. The solution is to shell out the clams for the Racetech rebound Gold Valves.   In addition, the stiffer spring will raise the front of the bike a little.   This will cause slower steering.   Compensate by raising the fork tubes a bit.   I had mine raised 15mm and I thought the bike handled GREAT.   However, at extreme lean angles you will touch down the right header pipe.   Don't ask how I know.   FWIW, I currently have 1.0 kg/mm Ohlins front springs.

UPDATE!!!   I found that the stock damping rod needle valve has a "step" to it.   This step does not allow the needle to fully seat into the rebound valving.   I CAREFULLY ground the step off of the needle and continued the same taper as the tip of the needle.   I now have sufficient rebound for the stiffer springs.

UPDATE!!!   The grinding of the rebound valve seat is a work-around!   The correct answer to the problem (not enough rebound damping) is to have the forks revalved.   The rebound shimstack just isn't stiff enough for anything other than stock springs.   If you would like your forks revalved I have come up with an awesome combination. You can read further information by searching on the SuperHawk Forum.