Join Date: Oct 2018
Location: Westchester County NY
My rear suspension upgrade
Model 2014 CTX700D DCT
Bought used in the fall with ~8k miles
Rider weight with really really heavy gear, > 250 (my gear is really heavy)
Coming from a Majesty (400cc scooter), I was hoping for significantly improved suspension over the scooter style CVT mounted on the swing arm. As I quickly experienced, the suspension was way too soft, and even cranking preload to the max didn't change the harsh ride. I was considering the Gonzo mod, and luckily picked up what looked like almost a brand new 2016 shock, with linkage for about $60 on ebay. One thing I noticed right away was that the new shock had more threading, which would allow more preload out of the box.
But more reading on the topic slowly dissuaded me from this approach. I came to the conclusion that I would need a different spring, at the least. Much better mechanics than myself were able to change the spring, but it would require some fabrication that was well out of my abilities.
I looked around and found the penske and ohlins options, which were still out of my price range. But extending the search to overseas vendors and including shocks designed for the NC700S, dramatically increased available choices, including Mupo, Hyperpro, Hagon and YSS. The cheapest option was YSS. One thing that gave me some comfort with the YSS is that it is well documented online. This made it relatively easy to find all the models and specs and opened up some more choices. More importantly, I knew what kind of spring it would come with and it was pretty simple to buy drop in replacements with all sorts of different rates. Someone with more experience would know which spring they could drop in as a replacement and where to get them.
The shock itself was compression rebound and height adjustable out of the box. The height adjustment was important and allowed me to settle on the model that was designed for the NC750X which I could shorten by 5mm to 300mm at the shortest. That's less than 5mm longer than stock, which I figured wouldn't result in too high a seat heigh, or require a new kick stand. I found the YSS for $275 plus about $50 in shipping. That was an investment I was comfortable with.
I think I got this next part right. But here's the data I collected. The YSS springs are spec'd in N/mm and this shock came with a 150 n/mm spring. That translates to 856 lb/in. According to RaceTech, the OEM spring on the CTX are 18.98 kg/mm. That translates to 1063 lb/in. Since my "gear" is so heavy, I guesstimated I'd need a much heavier spring. I found another YSS spring with the same length and width with a 265 N/mm. According the online calc I found, that spring was approximately 1400 lb/in. That seemed right to me.
Now changing the spring seemed like it was potentially one of the more challenging aspects of the job. I won't delve into all the detail of attempting to use a spring compressor I found on amazon, or the ratchet method I had seen on some Youtube videos. What I realized after some trial and error was that all I needed to do was back off the preload until the spring cap came loose on its own. That's kind of big deal with regards to the design of the shock, and I'm a little surprised that its not marketed a little more clearly. Basically, you don't need anything special to change the spring, just unscrew the preload until the cap slides off.
Another selling point of the YSS is that the preload is adjusted with a better mechanism that the two nuts requiring a spanner. There's one nut, and you can insert the 8mm steel bar directly into the nut to tighten. It's much much easier than the pair of nuts that need to be whacked with a screwdriver.
Anyway, the result is that my static sag is approx 17mm, and my rider sag is about 37mm right now.
Next up are the forks.