Many thanks. Every little helps.Well, all I can offer is that I spoke to a YSS US distributor several times, about 5 years ago, regarding a set of twin rear shocks for an NSS250 Reflex scooter. In the end I passed on the deal because I didn't get a good vib from the seller. He seemed to be just telling me whatever I wanted to hear regarding the potential performance of the shocks. When it came to make a deal he was out of stock of the exact unit I needed, and I would need to compromise a bit, so I dropped the idea altogether. I realize that doesn't tell you anything about the product itself, but that was my experience.
If you measure sag with you on the bike and preload set for your weight and then measure sag with the bike unladen the relationship of the two sag numbers can tell you if the spring is OK for your weight. If you can adjust preload to get the laden sag to 25-30% of travel and then have 5-10 mm of unladen sag the spring is good for your weight. If the unladen sag is less than 5 mm the spring is too weak for your weight.In most shocks where there is no compression rebound adjustment, the factory seem to build in too much compression damping from the getgo. As such the ride can be harsh until the shock wears, and that can take some time. I was afraid of that possibility with this unit but I was pleasantly surprised to find that there is just the correct amount of compression damping for me. I pushed the little bike hard yesterday over very rough roads that I normally use to test suspension, and some dirt roads. I had several stops to adjust rebound damping and all seemed well with a pleasant change from the OEM shock.
I initially thought that the Spring was a little on the weak side for my weight as I had to put on two full turns of preload to get some decent height to the rear of the bike. The Jury is still out on that aspect but overall I am happy. I may add another turn of preload but not just yet. The shock body was warm but not excessively so after 100kms of bumpy roads. That imho bodes well also. Now I will get on with riding it and hopefully reliability will prove to be good too.