Questions on pre-install & post-install rear shock absorber adjustments - Yamaha R3 Forum
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post #1 of 1 Old 09-03-2018, 07:16 PM Thread Starter
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Questions on pre-install & post-install rear shock absorber adjustments

I haven't found the OEM rear shock that awful given my conservative riding habits, and increasing the preload a while back got rid of most of the behaviour I didn't like. But I have wanted to be able to adjust and control rebound damping which is still a bit of an issue, and I thought that the OEM shock absorber is pretty heavy at 6.54 lb and does not work well enough to earn the right to be overweight.

I considered and rejected a number of aftermarket shocks, including the Ohlins offering. For those who are wondering why I would reject the Ohlins shock despite its great, and deserved, reputation:

- For me, in Canada, the best price on the shock with sales taxes is just under $1100 Canadian, and the install labour would be $125, so at least $1225 Canadian total

- It is obvious that the price is "brand driven" versus "worth" driven, because an Ohlins shock for the Honda Grom, where buyer price points are a lot more restrictive, is only about $650. (Marketing lesson here)

- The Ohlins shock is HEAVY - within 0.5 lb of the OEM one!

- I am not wild about having that remote cylinder attached to the left side of the bike

The combination of high price and high weight was just too irritating for me.

But the YSS MZ366-280TRL which has easy preload adjustability, length adjustability, and super easy and convenient rebound damping adjustability, and that is claimed to weigh 4.33 lb looked good to me, and I found a source where it would cost me $426 Canadian. So, with install labour, total cost would be $551. Plus, the YSS shock is "upsidedown" versus the OEM shock. i.e. the heaviest part of the shock attaches to the frame versus the swingarm, minimizing the unsprung weight. This all made the YSS shock look a lot better to me than the Ohlins, given my rather modest demands on a rear shock.

When the shock arrived, I was a bit disappointed to find that its actual weight was NOT 4.33lb, but rather 4.62lb, but it's still 1.92 lb lighter than the OEM shock, and 1.4 lb lighter than the Ohlins.

So, now I have the shock in my hands, and a 9-11 appointment with the local Yamaha dealer to install it. I want to do the install and setup correctly, so here are my questions:

1. SHOCK LENGTH: What is the length of the OEM shock?

2. SHOCK LENGTH: The shock length is easily adjustable within the range of 275mm to 285mm. I had to drop my front end just 2 or 3 millimeters when I installed the Vortex clip-ons, in order to expose enough fork tube length above the triple to properly mount the clip-ons (to get full engagement of the clip-ons). So, that minor adjustment from OEM geometry "steepened" the front end a bit versus stock. I favour agility which implies setting the shock longer than OEM length so that the rear of the bike is raised a bit more maybe. But, I don't want to make the bike "twitchy" or prone to speed wobbles. What length should I set the YSS shock at? For what it's worth, the center-of-eye to center-of-eye length of the shock in its shipping box is 11 inches = 280mm as shipped from the factory. So it is shipped pre-adjusted to exactly midway within its adjustability range.

3. REBOUND DAMPING: The rebound damping is easily adjustable through a dial with a 60 click range, so I figure I can play with that easily after the shock is mounted. But, will turning that dial become "harder" after the shock is installed? And what's a good starting point within that 60 click range?

4. PRE-LOAD PRIOR TO INSTALL: The preload is adjustable via a typical metal ring with spaced holes in it to accept a roughly 1/4" rod tool that is supplied with the shock, along with a 3mm hex wrench to loosen and retighten the locking screw on that ring. But getting the rod tool into the spaced holes could be a little difficult once the shock is installed, so getting into at least the right ballpark before install would be helpful. So, is there a sensible "starting point" adjustment I should make in the preload, before install, if that is even possible when the shock is not firmly held in one place by the bike itself yet?

My R3 is lightened by 44 lb versus stock, but I weigh 195 and I add on about 16 lb of safety gear when I ride, and Yamaha probably assumes a 175 lb rider, so my "net" weight versus stock is maybe only 8 lb lighter than Yamaha would have assumed, and rough weight distribution measurement via bathroom scale says that 54% of bike and rider weight is on my rear wheel.

5. PRE-LOAD AFTER INSTALL: After I have the shock installed, I assume I should take 2 measurements:
- Sag (versus the starting length of 280mm) with just the bike's weight on the shock
- Sag (versus the starting length of 280mm) with bike weight and MY weight on the shock
But, after i get those 2 measurements, how do I determine if I am in the right pre-load range, or how far to adjust the pre-load?

Jim G
JimGnitecki is offline  
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