2007 ST1300 fork oil upgrade

[Beagledog]

Can someone tell me if this is worth it...
I was talking to someone at work that builds his own bikes about my desire to upgrade my suspension in front and rear. He had an inexpensive suggestion of putting thicker fork oil to make it a bit more stiff.

Has anyone tried this? Will it help? I know it won't be the same as a $2K upgrade, but anything to help the ride...

 

[Marshal_Mercer]

Can someone tell me if this is worth it...
I was talking to someone at work that builds his own bikes about my desire to upgrade my suspension in front and rear. He had an inexpensive suggestion of putting thicker fork oil to make it a bit more stiff.

Has anyone tried this? Will it help? I know it won't be the same as a $2K upgrade, but anything to help the ride...

Unless you weigh over 250 pounds, going heavier on the fork oil should buy you nothing that you would like, i.e. a stiffer ride with no other handling changes.

Then again, what the heck! Give it a try. As you said: it's a cheap upgrade; or not.

Marshal

 

[wjbertrand]

I think 7wt is standard. I tried 10wt when I replaced the front springs with Sonic springs. I found 10wt too harsh and went back to 7wt. I'm thinking about trying 5wt, just to fully bracket my research on the subject.

 

[Marshal_Mercer]

I think 7wt is standard. I tried 10wt when I replaced the front springs with Sonic springs. I found 10wt too harsh and went back to 7wt. I'm thinking about trying 5wt, just to fully bracket my research on the subject.

IIRC Honda's 8 fork oil is actually 10 weight. I used 10 wt with stock guts, and 7 wt with Sonic Springs as well. I now use 2.5-5 wt with the Race Tech dampers and Sonic Springs. 7 wt seems about right for stock internals. 10 wt in the stock fork was way too firm for me. Jarring almost. Perhaps too little air in the fork.

Be advised though, that not all oils' weights are equal. Red Line fork oil seemed to me to have the viscosity that they stated on their package where others varied considerably.

Marshal

 

[Tazmool]

My old XX did not feel too stable when I 1st got it (bought it used) before I did anything suspension wise (anything involving upgrades & $$$) I pulled the front forks off, and flushed & replaced the fork oil with nice 100% synthetic yet stock weight oil, making sure the levels were at the correct heights etc.

Wow, what a difference to the bike that made!
The XX was far more stable when leaned over, and far less bouncy/squishy, I ended up leaving the suspension alone as it worked great!

I am 100% positive, my ST needs the same treatment right now as well.

Tazmool

 

[pretbek]

billxp improved the fork suspension on his ST1300.

He told me the ST1300 is undersprung and overdamped. So you can greatly improve the behavior of your steed by putting stiffer springs in and lighter oil.

The stiffer springs will prevent the sag, dive and wallow of the front end.
Thicker oil would only make it harsh and nasty over bumps.

 

[tlartist]

Replace the front springs with sonic appropriate to your weight and use a good synthetic fork oil like red line. Around $100-120. That is about as cheap as you can get for a significant improvement. Do the work yourself if you are able. Also it is viscosity not oil weight you are concerned with. An even mix of medium and light red line should work well.
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[jnsgardner]

I did the Race Tech upgrade. They said for my weight, 190lbs, a .95 would be right. I'd read Sonics were 1.2 to 1.1, but I went with their recomendations, and I couldn't be more pleased. It's now a plush ride, but...how to explain. in the corners, it's not like a Cadillac. Smooth and firm, with no surprises. If there's a hole, of course, there's a bonk, but it doesn't make you waver. I went for Race Tech because they're kind of local, a few hours made such a difference. A plush ride on the straights didn't mean something saggy in the corners. Whatever they did, it's a Cadilac on the straights and a Corvette on the corners.

John

 

[dduelin]

The ST1300 comes with SS8 Showa oil and that is "10 wt" but like what has been stated the only oils you can compare weights like this are oils in the same brand. The SAE method of grading oils by weight does not work with very low viscosity lubricants so one brand of 5 wt fork oil may actually be heavier than another brand's 10wt oil. That said you could try Honda's SS7 oil which they call 5 wt or mix SS8 with SS7 50/50 to get 7.5 wt.

I vary weight in the 160-165 lb range. The stock spring is .86/kg and one of the popular aftermarketers recommended .88/kg for my weight. The other was recommending 1.2/kg. Because I liked the stock spring action but found the sag excessive I increased the spacer length to 216 mm from stock 200 mm to get the sag in the correct range as an experiment. I replaced the oil with stock Showa SS8 10 wt and found the forks too harsh and skittish with the extra 16 mm preload. I mixed 2 parts Showa SS7 and 1 part SS8 to get 6.7 weight and tried that with slightly less oil to allow more air in the fork. I have been very happy for about 10,000 miles with this combination. All I can say is the ride is better - plush yet nicely damped and controlled - and the handling is better as well with the bike riding higher in the suspension travel it doesn't wallow down around the headstock and pogo in transitions.

Without a doubt I would not increase fork oil weight alone.

 

[jbird24]

I did the Race Tech upgrade. They said for my weight, 190lbs, a .95 would be right. I'd read Sonics were 1.2 to 1.1, but I went with their recomendations, and I couldn't be more pleased. It's now a plush ride, but...how to explain. in the corners, it's not like a Cadillac. Smooth and firm, with no surprises. If there's a hole, of course, there's a bonk, but it doesn't make you waver. I went for Race Tech because they're kind of local, a few hours made such a difference. A plush ride on the straights didn't mean something saggy in the corners. Whatever they did, it's a Cadilac on the straights and a Corvette on the corners.

John

How much oil capacity for two forks to replace oil

 

[SMSW]

Read Post #2. Thank you, @TerryS .