Fork oil too thick,or spring spacer?

[81gs7501166]

81 gs 750, with 82 1100 front end,time to change the oil.
Drained the black thick stuff,flushed with atf,let drain bout hour.
Added 8 Oz bell ray 10w fork oil in each fork.
Made a 3/4 in spacer on top of spring.(was trying this to help stop front from dropping so fast when let off throttle from a hard run up to 100mph).
0 psi I. Air forks.
It worked as far as the drop !
But now it's harsh, feel every bump in road, still have bout 1in of sag when on bike.
Is it too thick oil, or the spacer that is causing this?
I'm going back in and do something?
Either half the spacer or remove completely?
Or try ATF, bout 7wt instead of the 10w oil?
Ideas, recomandations?
Thanks

 

[Steve]

Have you changed the springs? :-k

I can't imagine stock springs being too harsh, though.

You need to start with basics, instead of applying Band-Aids over bandages. Rather than simply adding another spacer, pull the springs out to see what is actually in there. If you still have stock springs, it would be worth your time and effort to put some new, PROPER springs in there, instead. The two choices that are rather affordable are Progressive Suspension and Sonic Springs. Progressive claims a smoother ride with the progressive rate. Sonic claims a smoother ride and better control with a straight rate spring. Having ridden both, I prefer the Sonic springs. In the "for what it's worth" department, the owner of Sonic Springs is GSR member Rich Desmond. Unfortunately, we don't get a discount, but we buy his springs anyway.

You will need to use the calculator on the Sonic website to see which rate to get. When you install them, measure from the top of the installed spring to the top of the extended fork tube, cut a spacer about that long. Installing the cap on the tube will give it just about the right amount of preload. Check for "sag", it should be 20-25% of travel, or about 1 inch. Add the proper amount of oil. 10w should do just fine, in spite of what you are feeling now. The 8 oz. of oil that you added was just under the 8.3 oz. specified, but it's actually more important to have the same LEVEL, which is specified at 7.7" from the top of a fully-compressed fork with no spring in it. Many tuners recommend about 6", as it gives a higher progression rate with the smaller volume of trapped air.

Adding a spacer only raises the ride height, it will not prevent "dropping so fast when let off throttle". Thicker fork oil will not prevent diving or bottoming of the forks, either. You won't dive as quickly, but it will still dive, because it's the SPRINGS that keep you up. The manual for the 1100 calls for 15w fork oil, so your 10w is definitely not too thick.

.

 

[RichDesmond]

...I can't imagine stock springs being too harsh, though...

Ah, the miracle of too much preload. Even too-soft springs can feel harsh, effectively giving you the worst of all worlds.

 

[81gs7501166]

Cant buy springs now, not sure which if I could. I like the plush ride,it really rode great before I changed oil and added Spacer?
Just wondered what caused this,if I'm reading right, the spacer is the Problem?
I'll remove it today.
Thanks
Now as far as the P vs S springs,which gives the plusher,softer Ride?
I'm not really into fast curves,it handled great to me the way it was,
I just don't like the dive when letting off Gas?
Guess maybe u can't have plush ride and no dive?

 

[Steve]

Cant buy springs now, not sure which if I could. I like the plush ride,it really rode great before I changed oil and added Spacer? ... Now as far as the P vs S springs,which gives the plusher,softer Ride?

Progressive springs have a 'softer' section to the winding, but that is usually taken up by sag and preload, leaving you with just the stiffer section, and that is after you have already used up about half of your travel. Sonic springs have a constant rate, giving you control right away. As I mentioned in post #2, I have had both, and prefer Sonic.

The price difference is minimal, both are well under $100.

.

 

[Wingsconsin]

​The best you know is the best you rode -
If you liked it the way it was -- doesn't really mean it was operating properly.
Once the upgrade (update) is done correctly you will find the ride is much better than you imagined.
Perhaps you simply have not experienced a proper ride yet?

As for the P vs S issue...
I have tried them both and prefer the Sonic springs with proper pre-load spacer
While doing the forks new seals, correct oil, and springs is the way to go..
All new and working together to give you a plush yet controlled responsive ride.

Once the front end is fixed you may notice issues with the rear end too..
Often we perceive the ride to be poor due to forks - yet it is actually the rear shocks showing age and wear.
Best of luck getting this right for you in the near future.

 

[81gs7501166]

I liked the extra bit of firmness with the spacer, it was the feel every bump in road I Hated?
It was like the forks were slow to React?
I'll be able to get spring gs after first of Year!
Just want it to be a mod I like and not Regret?
I've replaced a lot of front end parts, but my tuning experience is little to none?
I do have hagons on rear.
I get bout 1in sag at each end.
Thanks

 

[RichDesmond]

Cant buy springs now, not sure which if I could. I like the plush ride,it really rode great before I changed oil and added Spacer?
Just wondered what caused this,if I'm reading right, the spacer is the Problem?
I'll remove it today.
Thanks
Now as far as the P vs S springs,which gives the plusher,softer Ride?
I'm not really into fast curves,it handled great to me the way it was,
I just don't like the dive when letting off Gas?
Guess maybe u can't have plush ride and no dive?

Take that added spacer out, that should help.

Somewhat counter-intuitively, stiffer springs can actually be more comfortable. If the springs are too soft you'll get a lot of motion and rocking out of the bike, and also bottoming which obviously will cause a harsh ride.
Straight rate springs make the best use of the available travel and allow the ride to be both plush and controlled.

 

[BigD_83]

Rich,

in terms of the rate calculator on your website, what do you recommend for someone who comes out at a between-rate. For example, if the calculator says 0.95 for an aggressive street rider, but 0.9 for a normal street rider, would it be better for that rider to tool up for the higher rate, even if the aggressive riding only happens 25% of the time?

 

[RichDesmond]

Rich,

in terms of the rate calculator on your website, what do you recommend for someone who comes out at a between-rate. For example, if the calculator says 0.95 for an aggressive street rider, but 0.9 for a normal street rider, would it be better for that rider to tool up for the higher rate, even if the aggressive riding only happens 25% of the time?

It depends. Generally on these older bikes you're better off with the lighter of the two, but sometimes not. Not something to worry about too much, the 0.05 difference is so small that it's hard to feel, and you would be just fine with either.
How much do you weigh?

 

[BigD_83]

Me, I weigh 175 fully geared up.

As Steve had mentioned the rate calculator, I thought it might help the OP to have some idea about what the various rates translate to in terms of performance/ride comfort.

In my case specifically, the stock spring rates available for the 650G are 0.8, 0.9, and 1.0 kg/mm. If I were buying and didn't want to go with a custom rate (say 0.95), then I'd have to choose between 0.9, which is probably the best case scenario for most of the riding I do in the city, or 1.0, which I think would work best on the one or two more spirited riding trips I do during the summer. However, I get the feeling the 1.0 would be a little harsh for everyday riding.

 

[RichDesmond]

Me, I weigh 175 fully geared up.

As Steve had mentioned the rate calculator, I thought it might help the OP to have some idea about what the various rates translate to in terms of performance/ride comfort.

In my case specifically, the stock spring rates available for the 650G are 0.8, 0.9, and 1.0 kg/mm. If I were buying and didn't want to go with a custom rate (say 0.95), then I'd have to choose between 0.9, which is probably the best case scenario for most of the riding I do in the city, or 1.0, which I think would work best on the one or two more spirited riding trips I do during the summer. However, I get the feeling the 1.0 would be a little harsh for everyday riding.

Yep, definitely the 0.90s. One thing to remember is that "aggressive" in the calculator is meant in the context of a modern bike, with modern tires and brakes. Older bikes aren't going to be able to generate the same kind of suspension loads.

 

[81gs7501166]

Took the spacer out,cut it in half, now only bout 3/8 in, I'm trying this and atf .
Test later today hope?

 

[Steve]

Took the spacer out,cut it in half, now only bout 3/8 in, I'm trying this and atf.

Then, when you test it, you won't know which mod made the difference.

Whenever you are trying to improve something, change ONE thing at a time.

.

 

[Steve]

I liked the extra bit of firmness with the spacer, it was the feel every bump in road I Hated?

I had a somewhat similar problem several years ago with a Kawasaki Voyager 1300. It was perfectly smooth and comfortable most of the time, but any kind of bump that was larger than an expansion joint on the freeway felt like the forks were solid. Found that the oil level in the forks was too low. The level was a bit below the holes in the damper rods, which meant that the springs were doing just fine on smooth roads, but when I hit any kind of bump, the dampers basically did a belly flop into the oil. It was that sudden change in damping from none to ALL that was so uncomfortable. I changed the oil, put in the recommended amount of 10w fork oil and enjoyed the ride. It was no less smooth on a nice road, but the controlled damping on the rougher stuff was REALLY nice.

.

 

[Steve]

Somewhat counter-intuitively, stiffer springs can actually be more comfortable. If the springs are too soft you'll get a lot of motion and rocking out of the bike, and also bottoming which obviously will cause a harsh ride.
Straight rate springs make the best use of the available travel and allow the ride to be both plush and controlled.

I had that concept in mind when I ordered springs for my 850. I believe the available rates were 0.9, 1.0 and 1.1. Since the 850 was the heaviest GS made (except for the 1100GK), and I have added the fairing and essentially turned it into a GK, I went with the 1.1 springs. Went with 10w oil, have not regretted a single mile with that combination. In fact, I do believe that it rides better than my Wing.

.

 

[salty_monk]

ATF is a crapshoot as it has no fixed weight..... Even various fork oils show a lot of variance between brands.

Get the correct weight spring & if your main issue after that is still fork dive put in a cartridge emulator. You can then run a lighter oil for rebound & adjust the emulator to suit on the compression side.

If you are getting a lot of bottoming out you can play with oil height in the fork leg. More oil means a stronger ramp at the end of stroke as the air above the oil compresses.

 

[81gs7501166]

Even with the spacer only 3/8 in, too slow to react,too much preload.
I removed spacer completly,added 8.5 Oz atf,nice and plush now,I'm leaving it alone until I can do springs.
I'm still undecided on p vs s?
Thanks

 

[RichDesmond]

Even with the spacer only 3/8 in, too slow to react,too much preload.
I removed spacer completly,added 8.5 Oz atf,nice and plush now,I'm leaving it alone until I can do springs.
I'm still undecided on p vs s?
Thanks

My 2 cents.

http://sonicsprings.com/catalog/straight_vs_prog_tech_article.php

 

[cowboyup3371]

I'll add another vote for the Sonic Springs and regular 10w fork oil is all you really need in my opinion