I recently replaced the tired front springs in my bike with sonic springs .90 which is the appropriate spring rate for my weight, and changed the fork oil with new oil.
The ride is better now but it is not as smooth as i was expecting it would be. The front seems pretty rough when going over bumps in the road, but maybe that is what it is supposed to be like and i am not use to it. I have just a little bit of pre-load on the springs with the pvc pipe that was sent with the springs, maybe 1/2" or so and the oil is maybe 4.5" below the top of the fork. (the manual says 4" for the stock springs, i did that and it was too stiff it wouldn't compress all the way).
Should there be less oil in the forks or is there another way to adjust the suspension or is this how it should be?
The tech side of it... no idea... rich desmond is the best man for that! ..
What you are feeling though... yep, they are a fair step stiffer than stock! .. I noticed mine jiggles around a bit like a supersport now... not quite that stiff but similar ish?
Providing all mech/tech issues are ok. .. you will adapt to it! :thumb: .. give it some more pressure through corners and under braking and the good points immediately outshine the 'niggles' ;)
Not diving while braking is a huge plus for the new setup, it may be something i just have to adjust to is all.
Omg I hate that too!!! I am getting ready to replace my fork seals and switch to 20wt oil... I only weigh 130lbs so I thought I'd try a heavier oil before I spent the money and upgraded the springs too.
Well, a couple things you could do here.
You could install cartridge fork emulators in your forks. Those are lauded for smoothing out the compression damping operation of these simple forks immensely, and they are tunable. That's all they alter, however. If you want to tune your rebound damping, you'll have to play with oil weight until that feels right for you.
Have you set your sag correctly? If you haven't, there are ways to measure that to make sure it's within proper effective range for you.
You may want to look over this thread for info about that. http://gstwins.com/gsboard/index.php?topic=68659.msg825970#msg825970 (http://gstwins.com/gsboard/index.php?topic=68659.msg825970#msg825970)
http://www.gostar-racing.com/club/motorcycle_suspension_set-up.htm (http://www.gostar-racing.com/club/motorcycle_suspension_set-up.htm) This site also helped me a lot.
Also, once you set your front sag, be sure to check your rear as well, since it will be altered slightly due to the stiffer front.
Last thing, oil height is also important. It's likely you put too much oil in your forks if you followed the amount that stock calls for. The stock springs are much smaller than the sonic springs and require more oil than the sonics will. I think that thread here I linked touches on oil height. If it's too high, it'll make your forks stiffer. If it's TOO high, it could blow your seals and cause damage. So check that soon.
Iarn might have hit it on the head..... I can't remember what Sonic Springs calls for in regards to oil level, but I know it's a very specific level. Search around a little here on the Twins site and on Desmond's site - I bet you find it quickly.
Several points:
It may just be that you want a softer spring. A .85mm/kg or .80mm/kg rate may be better for you riding style, road surfaces, preferences, etc. Just because sonic recommends .90 for your weight doesn't mean that that rate is 'perfect' for everyone. RaceTech recommended .80 (street) or .85 (track) for my weight, but I knew I wanted something a bit plusher for sport touring. So I went with .75 and couldn't have been happier.
What weight oil did you use?
I can't recommend strongly enough Iarn's suggestion at Racetech fork Emulators. The stock fork is as old school as it gets: It has 1 compression rate. Ideally you want a plush fork when you hit a big bump, so it doesn't rip the bars out of your hands. But at the same time you want a stiff fork while braking and accelerating to keep the bike more level. If you only have 1 compression rate then you have to pick a rate that is too soft for braking, but too hard for large bumps. On the other hand, if you pick up a set of racetech gold valve cartridge emulators you can tune both high and low speed compression rates; such that it will be stiff when you need it to be and still be plush over bumps. It is the best $150 you can spend on the GS. I would go as far as to say that a bike with stock springs and emulators will probably handle better then a bike with just stiffer springs.
What weight fork oil did you go with? I'm 170 pounds without gear and I went with progressive springs but 15w is a pretty good weight for me. Not too squishy and not too stiff.
Here is what rich from sonic springs told me when I did the change :
115-120mm range works well on the GS500s. Measured with the springs and spacers removed.
Er .. For the oil level, that is.
I went for a longer ride this past weekend and it feels better, that just may be me getting use to it a bit more. I am using 15w oil. Those cartridges do look nice maybe an upgrade down the road. I have not made any modifications to the rear spring, stock rear for now.
Is there a big difference in the feel and handling when upgraded to say an r6 rear shock. I know there are a lot of discussions on this forum about it but is upgrading the rear more of a priority than improving the front suspension even more with say a cartridge?
Front suspension on this bike will always have priority over the rear. The rear is manageable, the front is way too squishy for most riders.
Changing the rear or not is really the decision of the rider. Some users here have never changed their stock shock and they liked it fine. It depends on your situation. If the stock shock fits your weight range, and you don't feel it bottoming out, I think many here would suggest there would be no need to change it. If you use your bike in a very sporty fashion, it might leave you wanting a little, as stock has no adjustable compression or rebound damping settings, only preload. If you only use it for commuting and touring, maybe something like an R6 shock isn't that much of a need and the stock will serve you well enough (if its weight allowance isn't exceeded).
Haven't got cartridges on my bike, but yes ... once you do the front and feel the change/improvment then the rear balances things out more! .. depending on your weight, which shock AND setting that shock correctly for your weight and riding style.
When I did the sonic front end. . The rear ummm. ... Cadillac- esque (with my heavy weight) bounce? was more noticeable! .. felt slightly odd at times... so in went the katana shock and happy I was.
I probably could have gone with r6 unit, but budget and couldn't be bothered with the bit extra fiddling to install. ..pointed me at the katana.. 25bucks on eBay and 25 to ship to Australia from the states IIRC. ... cheapest r6 at that point was 130 ish just to buy?
Quote from: popnlock on May 11, 2015, 10:39:54 AM
I went for a longer ride this past weekend and it feels better, that just may be me getting use to it a bit more. I am using 15w oil. Those cartridges do look nice maybe an upgrade down the road. I have not made any modifications to the rear spring, stock rear for now.
Is there a big difference in the feel and handling when upgraded to say an r6 rear shock. I know there are a lot of discussions on this forum about it but is upgrading the rear more of a priority than improving the front suspension even more with say a cartridge?
Keeping weight off your wrists will make the springs feel more comfortable also (as well as improve your riding).
It takes both wheels working together to go around a corner, or over a bump. Having one fly end and one stone-age end is far from groovy. I would do a rear shock before the emulators, and if you find you really want to push your bike's suspension later on, then you add emulators. The R6 shock has all the same advantages over the stock shock that emulators have over a stock (even with stiffer springs) fork. It's been a long time since I got my R6 shock ($65) dialed in, so I'm pulling these numbers from my bum, but IIRC there are 8 preload settings, 32 high speed compression settings, 32 low speed compression settings, and 16 rebound settings. Plus if you need you can put on a different spring from racetech. It is WAY tunable.
Quote from: popnlock on May 11, 2015, 10:39:54 AM
I went for a longer ride this past weekend and it feels better, that just may be me getting use to it a bit more. I am using 15w oil. Those cartridges do look nice maybe an upgrade down the road. I have not made any modifications to the rear spring, stock rear for now...
You may want to try 10w fork oil. Most people like the 15w, but some do find that the 10w suits their riding better.
On the level, 115-120mm (which is about 4.5") is fine. When you measured it, did you have the spring and spacer removed, and the fork fully compressed? Measured from the top of the tube down to the surface of the oil, i.e actually measuring the air gap?