Fork preload spacer question XR600R.


17 replies to this topic
  • sploogemonkey

Posted March 31, 2008 - 01:04 PM

#1

I'll make this as simple as I can.

I bought heavier springs for my 600R. They're heavier than stock, but still undersprung for my weight. Long story short, couldn't pass up the deal, so I bought 'em.

They are Race Tech .46 Kg springs, new and never used, still in the box.

The springs are shorter than my stock springs, so I cut the PVC pipe to take up the difference plus I added 1.025" length since the Race Tech website states I should be running .57 Kg springs. I figured a little pre-load on the springs wouldn't hurt. I'm running Maxima 165/150 Fork oil at the recommended level. Compression adjusters on the bottom of the forks are set at 4 clicks out from seated.


The Question

With stock springs, there was no pre-load spacer needed. With these shorter Race Tech springs I need a 3.475" spacer plus I added an extra 1.025" to stiffen them up. Was this a bad idea?


The Problem

My bike doesn't like to turn anymore. Forks are too stiff and the bike doesn't want to "settle" into turns. Forks are too stiff and it feels like I'm riding on marbles under the front wheel and it just wants to wash out.

Next Move

I'm gonna set the compression adjuster to 8 clicks out from seated. (There are 16 clicks available). If the forks are still too stiff, I'm going to remove the extra 1.025" from the spacer tube in the forks. The fork oil I'm using is equivalent to 10wt oil. Maybe I should go down to 5 wt?


Input needed and appreciated.:prof:

  • Denn10

Posted March 31, 2008 - 01:23 PM

#2

i would try to remove the 1" spacer first, sounds like those bieng an 1" shorter than stocks that there not really for your bike. What series race tech springs are they?

  • sploogemonkey

Posted March 31, 2008 - 02:30 PM

#3

No dude.

The springs are not 1.025" shorter than the originals, they are 3.475" shorter than the originals. I made them a total of 4.5" long to have 1.025" longer for more pre-load on the springs.

The part number is FRSP3750-46. Exactly what is called for on the Race Tech website for my bike. The -46 is the spring weight (46 kg). http://www.racetech....angname=english


I'll call RT and ask them what the spring free length should be. Maybe they were mispackaged at the factory and I've got springs for a Vespa or something.:prof:

  • Denn10

Posted March 31, 2008 - 02:36 PM

#4

wow 3" shorter than stockers i wouldnt even try to make them work, now you got a Vespa 600R LMAO your a moped freak!!!

Posted Image

  • sploogemonkey

Posted March 31, 2008 - 02:43 PM

#5

Who you callin' a freak, princess?

I've had to deal with bein' 3" shorter my whole life, so shuddup! Yer givin' me a complex.

I'm gonna sneak into your trailer at the campout and leave a stinky steamy one in your toilet when ya ain't lookin!

  • martinfan30

Posted March 31, 2008 - 02:49 PM

#6

Who you callin' a freak, princess?

I've had to deal with bein' 3" shorter my whole life, so shuddup! Yer givin' me a complex.

I'm gonna sneak into your trailer at the campout and leave a stinky steamy one in your toilet when ya ain't lookin!


Why leave it in toilet if you are already in the sack with him?:prof:

  • sploogemonkey

Posted March 31, 2008 - 03:04 PM

#7

Why leave it in toilet if you are already in the sack with him?:bonk:


Oh it be on, biatches! :prof:

  • cleonard

Posted March 31, 2008 - 03:19 PM

#8

First those springs are correct. They need a spacer because they are not full length.

Second no one makes the .57 that you actually need. .46 is about as stiff as there is.

There is not a lot of extra room for compression on those shorter springs. Coil bind on compression is a real concern. I would take out the extra spacer and try it with the recommended length. You still need a tiny amount of preload on the springs so they are not totally free when the forks are 100% extended. See how you like it that way. Then try messing with the fluid.

I currently have 650L springs (.44kg/mm) and use ATF as my fluid. The ATF is 17 weight and I'm using it for bottoming resistance. The ride is quite harsh, but I'd rather have than then a crash from bottoming. Adding preload does not make springs stiffer. Only bigger wire or less coils can do that. I also need stiffer than .44 springs. My plan is to cut down the 650L spring and replace the cutoff part with a spacer. Assuming that I can cut off 3 or 3.5 inches the rate should get quite a boost. I ran the numbers once, but I don't remember. It's like .49 or .50 or something, but like I said I don't remember for sure.

  • sploogemonkey

Posted April 01, 2008 - 01:53 AM

#9

............There is not a lot of extra room for compression on those shorter springs. Coil bind on compression is a real concern. I would take out the extra spacer and try it with the recommended length. ......... Then try messing with the fluid.


Thanks for the reply cleonard.:prof:

I honestly hadn't thought about the consequences of coil binding, but it makes sense.

I'll make another set of spacers that are 1.025" shorter, which should give me no pre-load on the springs, but take out all the free space.

Can you help me understand the compression adjuster on the bottom of the fork leg? It has 16 available clicks. The previous owner had them adjusted 4 clicks out from seated. To me, this means softer compression stroke.

Compression and Rebound adjusters dampen the reciprocating hydraulic characteristic of the suspension component, right? So by increasing the damping, I'm slowing the respective action down, right?

If I fully increase the damping, I've retarded the compression and made the ride softer. If I fully decrease the damping, I've removed resistance to compression and made the ride harder.

So I should turn out from seated for more compression, and turn in towards seated if I want less compression?

Guidance, puhlease!

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  • cleonard

Posted April 01, 2008 - 06:35 AM

#10

A shock is not much more than a piston in a cylinder with a small hole. For the piston to move the oil has to pass through that small hole. The adjuster controls the size of the hole on the compression stroke. Fully seated means a really small hole. The hole gets bigger as the adjuster is moved away from seated.

For rebound the hole is fixed. The only adjustment is the viscosity of the oil. Go too thick and you risk a condition known as packing. That is when the forks don't rebound fast enough for the next bump. Usually most pronounced int he whoops. You end up with less suspension. With stronger springs you need more rebound damping to counteract the stronger spring force.

For a little extra spring action, I run the fork oil height about 5mm or so over the max recommended height in the Honda manual. That gives more air pressure on compression and that helps the springs.

At least that's my take on it.

  • Jonny Enduro

Posted April 01, 2008 - 05:10 PM

#11

Sploogemonkey, I'm having the same problems with xr250 race tech springs being 4in shorter than the stock ones. And trying to sort out the spacers. My problem is I did not get any instructions with my "good deal". Do you think I some how could get a copy of yours. Any help would be aprichiated

  • sploogemonkey

Posted April 01, 2008 - 05:27 PM

#12

I'll dig up the box that they came in and reply later tonight.

  • ghrati ghoti

Posted April 16, 2008 - 01:36 PM

#13

First those springs are correct. They need a spacer because they are not full length.

Second no one makes the .57 that you actually need. .46 is about as stiff as there is.

There is not a lot of extra room for compression on those shorter springs. Coil bind on compression is a real concern. I would take out the extra spacer and try it with the recommended length. You still need a tiny amount of preload on the springs so they are not totally free when the forks are 100% extended. See how you like it that way. Then try messing with the fluid.

I currently have 650L springs (.44kg/mm) and use ATF as my fluid. The ATF is 17 weight and I'm using it for bottoming resistance. The ride is quite harsh, but I'd rather have than then a crash from bottoming. Adding preload does not make springs stiffer. Only bigger wire or less coils can do that. I also need stiffer than .44 springs. My plan is to cut down the 650L spring and replace the cutoff part with a spacer. Assuming that I can cut off 3 or 3.5 inches the rate should get quite a boost. I ran the numbers once, but I don't remember. It's like .49 or .50 or something, but like I said I don't remember for sure.


Would you mind digging up your calculations? I came up with .485 rate required with the race tech calculator and eibach was the closest at .47.
If I cut 3", I add a 3" spacer, correct?

  • cleonard

Posted April 16, 2008 - 02:36 PM

#14

Would you mind digging up your calculations?


I'll try and find those links where I got the info. I'm super busy so it might take me a few days.

  • Denn10

Posted April 16, 2008 - 02:45 PM

#15

heres some i found hope it helps any, go to my 2nd post i think and there are some links

http://www.thumperta...ad.php?t=629854

  • ghrati ghoti

Posted April 17, 2008 - 05:06 AM

#16

heres some i found hope it helps any, go to my 2nd post i think and there are some links

http://www.thumperta...ad.php?t=629854


Thanks Denn! That's where I got my spring rate from. I was interested in how much needs to be cut off the stock .44 spring to make it closer to a .48.

  • ghrati ghoti

Posted April 17, 2008 - 05:27 AM

#17

Ah ha!
http://www.thumperta...ing fork spring

  • lunchmeat

Posted June 15, 2009 - 03:04 PM

#18

Cut PVC tubing into various sizes. I did + or - 10mm longer and shorter than race tech said then road the bike and changed them and figured the perfect preload. You need to play with the rear race sag and also notice the effects on how much or little the front dives in for you.
You want to set the bike up for woods and hard attacks or just meduim paced trails, or motocross type more for jumping. Your race sag will effect everything and puts a bike into two different modes. Pick you setup based on tracks or trails, plush and easy slower speeds in the woods or more open tails and high speed and or slamming it thru the woods, or jumping they all are different. Rocks? muddy? Woods riders need to know the front end will do what it needs to on fast downhills rocky or wet and perform for them. Set you preload according to your riding. As you get faster you will keep adjusting the preload for your faster abuse.





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