Front fork setup suggestions for heavy oil (15W)

I got my forks serviced a couple of months ago, and the shop used Motul 15W oil. I didn't think much of it until I felt the front was super stiff, leading to instability under braking and understeer when cornering. I checked the specs, and turns out it's rated at 58.1 cSt, which is nearly 4 times the viscosity of the stock Yamaha oil (15.6 cSt)!
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I looked into getting them serviced again with a lighter oil, and let's just say it's more $$$ than I want to spend right now, since I'm also trying to solve a bunch of other problems with this bike.

So what I'm looking for right now is any suggestion for a baseline setup that would turn this into a liveable setup (reasonable balance of ride on city roads, stability, handling). I backed off the preload and compression all the way in order to soften it up, but while it has helped it's not fully solved the problem - I had the forks bottoming out while still not giving me the comfort/stability I wanted.

Any idea what I could do? Even general ideas are welcome, e.g. "medium preload, soft compression, medium rebound" (just pulling stuff out of the air here).

(Just to be clear - I'm NOT looking at getting into the forks myself to check the oil level or change stuff. It's just not something I'm keen or confident to do. If I really can't find a workable setup, I'll have to take it in to a more trusted workshop to service, but I'm hoping it won't come to that)

Thanks in advance for the help!
 
I got my forks serviced a couple of months ago, and the shop used Motul 15W oil. I didn't think much of it until I felt the front was super stiff, leading to instability under braking and understeer when cornering. I checked the specs, and turns out it's rated at 58.1 cSt, which is nearly 4 times the viscosity of the stock Yamaha oil (15.6 cSt)!
er.gif


I looked into getting them serviced again with a lighter oil, and let's just say it's more $$$ than I want to spend right now, since I'm also trying to solve a bunch of other problems with this bike.

So what I'm looking for right now is any suggestion for a baseline setup that would turn this into a liveable setup (reasonable balance of ride on city roads, stability, handling). I backed off the preload and compression all the way in order to soften it up, but while it has helped it's not fully solved the problem - I had the forks bottoming out while still not giving me the comfort/stability I wanted.

Any idea what I could do? Even general ideas are welcome, e.g. "medium preload, soft compression, medium rebound" (just pulling stuff out of the air here).

(Just to be clear - I'm NOT looking at getting into the forks myself to check the oil level or change stuff. It's just not something I'm keen or confident to do. If I really can't find a workable setup, I'll have to take it in to a more trusted workshop to service, but I'm hoping it won't come to that)

Thanks in advance for the help!

Have you talked with the shop and asked them why they went with such a heavy weight oil? Maybe they'd be willing to swap it out at a discounted rate if you present the problem as a safety issue?

That being said, swapping out the oil yourself isn't that bad. It was one of those jobs that I was hesitant/nervous to do my first time as well but, other than significantly over-torqueing the fork caps, went pretty well! I followed the steps in this video and it worked out nicely:

 
The shop that did this botched a ton of stuff and I had a huge row with the owner. Neither one of us wants to see the other's face again, so that's a no-go 🤣

Thanks a lot for the video (and encouragement), let me watch it and see whether it increases my confidence to take on the job.

A couple of questions:
  1. Did you have to change the seals etc, or was it just a drain-and-refill job? I just changed the seals in that service, so would prefer to save the expense if possible
  2. Did you manage to get all the oil out (including what's in the fork body and the cartridge)? One shop said that draining the oil without removing seals would only get the oil on the outside, not within the cartridge, which would lead to inconsistent behaviour. No idea how true
Thanks again!
 
Happy to be of help!

I did not change the seals as they aren't leaking and look good, so just a drain and refill.

Just guessing here but would say I got 95%+ of the oil out. Probably could've gotten a little more but not worth the wait time/effort for that last little bit. I figure if I change it regularly, the old oil to new oil ratio is so minute, it won't make a difference.
 
It's well worth it just to do a drain and fill. Even getting 75% out is going to make an improvement. All you have to do is let it sit there for a while and it will drain and then turn them right side up and pump a couple times then turn back upside down for the final drain.

This ain't rocket science so don't overthink it. LOL
 
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