Rear Spring Preload on Kawasaki Vulcan 900 - Step-by-step Instructions & How it Works

I give step-by-step instructions and show how to adjust the rear spring preload on Kawasaki Vulcan 900. Adjusting is easy, but I also talk about how the rear shock absorber and spring preload work. Here is the practice and a little bit of theory at one place.

Motorcycle: 2015 Kawasaki Vulcan 900 Classic SE

Maintenance instructions in this video are applicable to the following motorcycles:
2006-2022 Kawasaki Vulcan 900 Custom
2006-2022 Kawasaki Vulcan 900 Classic
2006-2022 Kawasaki Vulcan 900 Classic LT

Do It Yourself $20 Motorcycle Jack in 20 Minutes (Made for Vulcan 900 Classic) video: https://youtu.be/CWeI_B0fjI8

Check other helpful videos:
How to Replace an Air Filter on Kawasaki Vulcan 900 - Step-by-step Instructions: https://youtu.be/NJUf1kwk7mw
Oil Change - Kawasaki Vulcan 900 - Step-by-step Instructions: https://youtu.be/Zv9A2nID9Ag
How to Install H4 LED "Sealight" Headlight on Your Bike - Step-by-Step Instructions for VN900: https://youtu.be/_HHJWvG4WGU

00:00 Intro
00:45 All the tools you need
01:23 Secure the bike using $20 DIY jack
02:00 Removing the seat to get access to the adjuster
02:50 Removing the left side cover
03:39 Removing the reservoir tank cover
04:27 Removing the reservoir tank
05:29 Don’t forget to subscribe!
05:41 Adjuster settings and what they depend on
07:33 Adjusting the spring preload
08:31 Re-assembling everything back
09:51 Putting the seat back
10:07 What is the Spring Rate?
12:09 Details about the spring preload and its adjustment
15:22 Thank you!

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Music:
Happy Rock, Composer: Benjamin Tissot, www.bensound.com

Today I'm going to talk about how you can adjust the rear spring preload on Kawasaki Vulcan 900. I will also talk a bit how the spring preload works.

First, we need to get access to the spring adjuster. Vulcan 900 has one shock absorber with a spring. It is here in the middle of the bike. Remove the seat first using the bike key. It might be a little tricky. Push the back of the seat down with your knee while turning the key. Then we remove the left side cover. In order to do it we need to remove the screw here on the top. Then carefully pull it this way. Then we remove the reservoir tank cover. For that we remove this bolt using Allen screwdriver also called Hexagon. Next, we remove the reservoir tank. Unscrew these two bolts first. Here is a little trick that makes it easier to work. When you remove the reservoir tank, hook this underpart of the reservoir tank to the holder of the frame.

The rear shock absorber spring preload adjuster has 7 positions, where the 1st one is the least strong, and the 7th one is the strongest. The standard setting position is #4 for an average-build rider about 68 KG (or 150 pounds) with no passenger and no accessories. This is according to the Owner's Manual. I guess they were just kidding saying that the average-build rider is 150 pounds. I consider myself an average guy, but I weight 83 kg (183 pounds). This means I had to adjust it almost right away. Also I ride a lot with my wife, and I have some accessories as well, such as saddle bags, a backrest, and a rear rack. Because of all of that I adjusted it to the preload #6 almost right away. I actually tried riding with my wife on the #4 setting and my rear suspension bottomed down on the first railway crossing, so I came back and adjusted it. What I would recommend is to try it on different positions and see how it works for you, but definitely, if you are more then 68 kg, do the adjustment sooner than later. Now we will use the hook wrench that comes with the motorcycle to turn the preload adjuster. Adjust the preload as you desire.
When you are done with the adjustment, you can assemble everything back together in the reverse order.

Now let's talk about how the rear suspension and rear spring preload work on Vulcan 900, or pretty much on any other bike. What is preload to begin with? Before we talk about preload, let's talk about a spring rate first. A spring rate is the figure measured in kg/mm (lb/inch) that shows how much weight we should apply at the top of the spring to compress it one unit of length. For example, on Vulcan 900 the length of the spring on the assembled shock is about 8.5 inches or 215 mm. The spring rate is about 500-550 pounds per inch or 9-10 kg per 1 mm. This means that we need to apply 10 kg at the top of the spring to compress it by 1 mm. The travel of the spring is about 2 inches or 50 mm. This is how much it can be compressed the most. It happens when the wheel travels 4 inches or about 100 mm. Now about the preload. Preload is a measurement of how much the spring is mechanically compressed when the shock is fully extended. Let's say the spring is pre-loaded by 7 mm on the setting #4, and the rate is 10 kg/mm, then it means that you would need to exert more than 70 kg of force down on the spring in order to begin compressing it.

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Видео Rear Spring Preload on Kawasaki Vulcan 900 - Step-by-step Instructions & How it Works канала K Max Video