Progressive Spring Upgrade - Help with Oil weight, Oil volume, and General Procedur - Kawasaki KLR 650 Forum
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post #1 of 18 Old 03-06-2011, 11:29 PM Thread Starter
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Progressive Spring Upgrade - Help with Oil weight, Oil volume, and General Procedur

I have a 2009 KLR-650. I'm upgrading my front end. I'm new to working on bikes in general and so I'm totally new to front fork work. I've been searching the forums for info on what weight fork oil to use when I install a new set of progressive front fork springs, that I just got in the mail, in a few days.

My bike is setup with Happy Trail Teton panniers, and a 45 liter Givi trunk box. and I'm hoping to do some good longish distance adventure rides this summer across the NW and up to Canada a bit. Today, I was testing some heated gear out on the superslab, and man the front end definitely is squirrely - especially around 70 mph in the stock configuration it's in now - and of course when coming up on and passing semis too. I'm hoping these progressive fork spring, fork oil change out, and fork brace mods will combine to help improve things - for the highway stability at least.

I weigh 220 lbs, and I ride a variety of - long distance highways and superslab (50%); dirt single track trails at the ORV park (20%), and logging roads (30%). I'm hoping to get some help on:

1) OIL WEIGHT - Which oils weights to consider and what they would do

2) OIL VOLUME - how much oil volume to put into my forks and how best to install it - I'm assuming from other posts, I will empty the stock oil out, and with the springs out - compress the fork before replacing with oil. Do I have to take the fork off the bike?

3) OIL MEASUREMENT and ADJUSTMENT - The best ways to measure the oil / remove what is not needed / get the oil equal. Do I need to buy a turkey baster?

4) SPACER LENGTH - How much spacer to use

5) PRE-LOAD RECOMMENDATIONS - What pre-load is recommended.

I'm not going to be spending any additional money on emulators or other fork parts. I do have a EM fork brace coming though, and I'm hoping the combo of oil, new progressive springs, and the brace will setup the front end pretty well.

Thanks much for any help you guys!

Bill

------------------------------
------------------------------
UPDATE: Images of the change out. I could not have completed these changes without all the help in the posts below from this group! Thanks much everyone!



More fork spring change out images here:
http://www.flickr.com/photos/6054519...7626122567129/

Last edited by Adventure-Moto; 03-19-2011 at 01:46 PM.
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post #2 of 18 Old 03-07-2011, 12:11 AM
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Oy, oy , oy....

The short answer is do what works for you.

Hope that helps...

But it really is the right answer.

What you have there are damper rod forks. They pump oil through a set of orifices - using the same orifices for both compression and rebound. There is no adjust-ability, really, beyond swapping the oil out.

I can't give you specific recommendations as mine have been rebuilt with emulators as well as the progressive springs and I have MotoWizard preload adjusters installed.

Let's take things in the order you asked:

Oil weight:


Don't go too heavy. Remember that your forks use the same orifices for compression and rebound. If you use too heavy an oil the springs will not be able to push the forks to rebound quickly, so they will be dead feeling and 'packed up'. You might want to start with ATF, as it is (IIRC) about 7.5 weight. Run it and see how it feels. It's cheaper than fork-specific oils and just about the same stuff. If you install stiffer springs and therefore need more damping, you're going to have to use a thicker oil. That will slow down the compression of the forks, making them stiffer still. If you install softer springs and want less damping to go with them, you need a thinner oil. Of course, the thinner oil will speed up the compression. That's the nature of damping rod forks and this is what emulators fix.

Oil volume:

You don't need to take the forks off of the bike. Start with the stock oil volume and see how it feels. The air in your forks acts like a spring. The more oil, the less air, and the harder the air spring will be. Less oil provides more air for a softer air spring. This is some tune-ability you can take advantage of. If you get your oil and springs working together but want just a tad softer feel/ride, remove some oil. That will reduce the over all spring rate of the forks.

Oil Measurement and Adjustment:


A turkey baster and some aquarium hose is the cheapest tool you can make for this, and it works. You can even buy the cheapest turkey baster you can find.

Spacer length/Preload:

Kinda the same question. Which springs did you get? I seem to recall that there are progressive springs that are the same length as the stock springs and there are some that are quite a bit longer. Were there manufacturer's recommendations? The preload needs to give you the right sag. Shoot for using about 1/3 your suspension travel in static sag. You said you were having problems with the front end hunting. You might want to try a tad bit more preload than you have now and see if that helps it.

Along those lines, the Gen2 bikes have a front fender that is as big as all outdoors. Get rid of it in favor of a 'tard fender. Much of your front end woes may very well be due to that front fender. My bike has a Cycra fender on it. Lockjaw has an Acerbis, Tomatocity runs a KTM, I think. All would be suitable and none would be much more than $25.

T

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Last edited by Tom Schmitz; 03-07-2011 at 12:27 AM.
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post #3 of 18 Old 03-07-2011, 12:40 AM Thread Starter
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Thanks Tom,

I just added one of these lower profile fenders to my list of coming parts for the front end improvements:
http://store.cycraracing.com/fasufrfeb1.html

I'll start out with the ATF then - and a turkey baster and some tubing too to suck out the old oil. I'll measure the volume level before I remove the old stuff. Or maybe I'll put the old stuff in something that I can measure, and put an equal amount of new ATF back in.

The new springs I got from Happy Trails - they are Progressive Suspension front fork springs part 11-1506 - for KLR-650, the box has some 3 inch sched 80 pvc spacers in it. Papers inside say to use the 3" of spacer for the 2008 model KLR-650.

Turkey baster and tubing next? Sounds a bit odd - does it not? Ha
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post #4 of 18 Old 03-07-2011, 12:53 AM
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Adventure-Moto -

Measure the height before you take it out. The easiest way to take it out is to pop the Allen head screw on the bottom of the forks and let it drain out.



Remove the Allen bolt from the bottom of the fork leg. This should come out easily. If it doesn't, then you're going to need to stuff an appropriate tool down the fork leg in order to hold the damper tube stationary.

Tom [email protected]

“The muzzle of the Luger looked like the mouth of the Second Street tunnel, but I didn’t move. Not being bullet proof is an idea I had had to get used to.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
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post #5 of 18 Old 03-07-2011, 12:59 AM Thread Starter
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Thanks again Tom,
Why do I need to hold the damper tube stationary - is it in order to allow the allen head screw to turn out?

Once it is out - and the oil is drained, assuming I can remove the allen head screw at the bottom - do I have to worry about getting the allen screw back in, or maybe when I took it out - releasing anything important on the other side of the screw?

Thanks much for the great help!

AM
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post #6 of 18 Old 03-07-2011, 02:08 AM
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Adventure-Moto, you're hep about measuring the HEIGHT of the oil surface to determine volume, and to equalize the amount in the forks, right?

Didn't think the technique had been mentioned on the thread so far.

DO NOT TRY THIS AT HOME, my dealership has a vacuum pump and graduated hose . . . they stick he hose down the fork tube to the desired "height" and then evacuate the excess oil 'til the desired level is obtained. The reason I say forget it at home; few "shade-tree" mechanics could afford/justify such a device!
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post #7 of 18 Old 03-07-2011, 08:41 AM Thread Starter
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Thanks Damocles for the help on fork oil volume determination. I also read in another thread that you need to cycle the fork a few times if it was drained, when you refill it, to make sure you get all the air out of the system.

So for a 2008 Model KL-650, fork fluid change out, and new Progressive spring installation, does this checklist sound right:

A) With the bike level and front fork tubes top main nuts, and stock fork springs removed, measure and record the volume from the top of the tube to the top of the oil level in the tube.

B) Drain the fork oil in both tubes, via the center hex bolt Tom refers to above, at the bottom of the fork assembly. (( do I Cycle the fork assembly to get all the oil out? ))

C) Replace the hex bolt used to drain the fork at the bottom of the fork tubes.

D) Install the new fork oil, to the same height as the "stock fork oil level" recorded earlier. (( ?? Be sure to cycle the fork assembly to get the air out when replacing fork oil ?? ))

E) Install the new Progressive front fork springs, and the 3" spacers on top of them.

F) Replace the fork top main nuts, and torque to (( I will look the torque value up in the clymer manual ))

G) Tighten the fork tube bolts to required ((I will look up the value)) torque value.

Last edited by Adventure-Moto; 03-07-2011 at 08:44 AM.
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post #8 of 18 Old 03-07-2011, 10:16 AM
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A-M -

That sounds about right.

The bolt in the bottom of the fork holds the damper rod in place. I was able to both remove and install the bolt with no problem, but there is a chance that the rod could spin. If that happens you need to fab up some sort of a tool to hold the rod in place as you tighten the screw. It need not be anything elaborate; a hunk of 1/2" dowel, three feet long, will do. Here's a picture of the damper rod:



T

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post #9 of 18 Old 03-07-2011, 10:18 AM
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Quote:
Originally Posted by Damocles View Post
Adventure-Moto, you're hep about measuring the HEIGHT of the oil surface to determine volume, and to equalize the amount in the forks, right?

Didn't think the technique had been mentioned on the thread so far.

DO NOT TRY THIS AT HOME, my dealership has a vacuum pump and graduated hose . . . they stick he hose down the fork tube to the desired "height" and then evacuate the excess oil 'til the desired level is obtained. The reason I say forget it at home; few "shade-tree" mechanics could afford/justify such a device!
.....

Quote:
Originally Posted by Tom Schmitz View Post
...

Oil Measurement and Adjustment:


A turkey baster and some aquarium hose is the cheapest tool you can make for this, and it works. You can even buy the cheapest turkey baster you can find.
...

Turkey basters are about $2. Some aquarium hose and a sharpie to mark the level completes the set-up.

T

Tom [email protected]

“The muzzle of the Luger looked like the mouth of the Second Street tunnel, but I didn’t move. Not being bullet proof is an idea I had had to get used to.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem

Last edited by Tom Schmitz; 03-07-2011 at 10:21 AM.
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post #10 of 18 Old 03-07-2011, 11:19 AM
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Quote:
Originally Posted by Adventure-Moto View Post
Thanks Damocles for the help on fork oil volume determination. I also read in another thread that you need to cycle the fork a few times if it was drained, when you refill it, to make sure you get all the air out of the system.

So for a 2008 Model KL-650, fork fluid change out, and new Progressive spring installation, does this checklist sound right:

A) With the bike level and front fork tubes top main nuts, and stock fork springs removed, measure and record the volume from the top of the tube to the top of the oil level in the tube.

B) Drain the fork oil in both tubes, via the center hex bolt Tom refers to above, at the bottom of the fork assembly. (( do I Cycle the fork assembly to get all the oil out? ))

C) Replace the hex bolt used to drain the fork at the bottom of the fork tubes.

D) Install the new fork oil, to the same height as the "stock fork oil level" recorded earlier. (( ?? Be sure to cycle the fork assembly to get the air out when replacing fork oil ?? ))

E) Install the new Progressive front fork springs, and the 3" spacers on top of them.

F) Replace the fork top main nuts, and torque to (( I will look the torque value up in the clymer manual ))

G) Tighten the fork tube bolts to required ((I will look up the value)) torque value.

I wouldn't try to take the springs out with the forks on the bike, you'll get oil everywhere. The only thing I would do with the forks on the bike is loosen the top cap (with the top triple clamp bolts loose of course).

I also wouldn't try to loosen the bottom bolt unless you want to pull the damper rod out. Chances are it will spin and you will have to have a tool to hold the rod. BTW you can usually use a length of PVC with a slot cut into it.

Here's how I do it:

1. Top triple clamp bolts loose, loosen fork caps.
2. Remove forks
3. Remove fork caps and springs, turn forks upside down and let them drain for awhile. Pump the forks to get all the oil out.
4. Fill with Mobile 1 ATF. Height is personal preference I would go with the stock height as you're changing springs and go from there.
5. I use a large syringe type thing with some clear tubing marked for height. Basically you overfill a bit and suck the oil down to the level.
6. Replace springs and spacers and start top cap.
7. Replace forks, tighten lower tripple clamp, tighten top cap and upper clamp.

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9

Last edited by Spec; 03-07-2011 at 06:35 PM.
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