for ST1300 what weight fork oil are you finding best 10 or 15?
Fork oil for ST1300
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Here we go! 
I use what Honda recommends... 10w... I did upgrade the springs in my forks though...
For my experience the best choice for me was a fork oil was mixing my own 2 parts Honda 5 wt SS-7 to 1 part 10 wt SS-8
to arrive at a true 6.7 wt.
Don’t choose by labeled weight unless you stay in the specific brand as SAE weights are all over the place between different brands. Weight is not a good indicator of the qualities of very light oils. Dig into the online fork oil charts listing the viscosity index and centistokes of various brands and weights and find that some fork oils labeled 5 act more like 10 and 10s that are closer to 5. Find in the charts the factory fill of Honda Showa SS-8 and if you want a thinner oil look above SS-8 and if thicker look below it. In my case I wanted an oil that allowed less compression damping and could live with the faster rebound damping of that choice. Staying in brand I mixed my own qualities.
www.peterverdone.com
to arrive at a true 6.7 wt.
Don’t choose by labeled weight unless you stay in the specific brand as SAE weights are all over the place between different brands. Weight is not a good indicator of the qualities of very light oils. Dig into the online fork oil charts listing the viscosity index and centistokes of various brands and weights and find that some fork oils labeled 5 act more like 10 and 10s that are closer to 5. Find in the charts the factory fill of Honda Showa SS-8 and if you want a thinner oil look above SS-8 and if thicker look below it. In my case I wanted an oil that allowed less compression damping and could live with the faster rebound damping of that choice. Staying in brand I mixed my own qualities.
Suspension Fluid - Pvdwiki
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I put the regulation 10W oil into mine, and frankly, I think it's a bit harsh and overdamped. 7.5W might have been better but it's such a faff doing it I'm inclined to put up with it for the next 50,000 miles.
When I rebuilt the fork on my '96 NH 750, I used a 10w fluid. I filled each tube 1/4" higher than spec, figuring it would effectively increase the spring rate slightly. I was very happy with the results.
Sidekick
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While the inherent stiffness of the ST fork is undeniable, suspension tuning is ultimately a personal decision.
After years of trial and error, I’ve found that using (true) 5W fork oil works best for me. I run 600 ml with Race Tech 0.90 kg/mm non-progressive springs and a 20 mm preload. At 160 pounds, and with very few instances of carrying a passenger, this setup provides a significant improvement. The fork is still a bit firm, but it’s much more comfortable compared to the harsher 10W oil and OEM springs recommended by Honda.
Though I believe installing Gold Valves would offer an even better ride, their cost is beyond my current budget. For now, I’m sticking with this setup, as finding the right balance between comfort and performance has been a challenging process.
After years of trial and error, I’ve found that using (true) 5W fork oil works best for me. I run 600 ml with Race Tech 0.90 kg/mm non-progressive springs and a 20 mm preload. At 160 pounds, and with very few instances of carrying a passenger, this setup provides a significant improvement. The fork is still a bit firm, but it’s much more comfortable compared to the harsher 10W oil and OEM springs recommended by Honda.
Though I believe installing Gold Valves would offer an even better ride, their cost is beyond my current budget. For now, I’m sticking with this setup, as finding the right balance between comfort and performance has been a challenging process.
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I went with ATF fluid which would be around 8-10 wt.
Really happy with the results with one up riding.
Haven’t tried it with a pillion on the back yet.
Really happy with the results with one up riding.
Haven’t tried it with a pillion on the back yet.
Which is what the Honda Brand Fork Oil is, if one were to send a sample to the lab to find out
except Honda charges four times as much
Honda use to recommend ATF be used for just about everything they made from dirt bikes to Goldwings, until somebody figured out they could market it and make a killing.
OP
OP
wow one needs a degree to understand the complications of the question, I wasn't aware of that. What on earth are gold valves?
Sidekick
Save Ukraine Stop War!
FYI,
Gold Valves - Race Tech
ENGINE SERVICES What are Gold Valves? Gold Valves® are Race Tech’s Custom Valving Kits. They are designed to break through the limitations of stock piston designs. Research has shown that the stock piston ports induce unnecessary harshness and inconsistency. Gold Valves are designed to reduce...
racetech.com