Jump to content
Sign in to follow this  

Spring and suspension upgrade help, 88 XR600R

Recommended Posts

Hi all. I've been spending some time polishing up my big red pig in time for prime dirt season. I need to replace the fork seals and maybe the bushings on my '88 XR600R, and this gives me an excuse to replace the springs front and back. The front end of the bike has always been way too soft for decent dirt riding and I've wanted to firm it up for a while. I looked at Racetech's site to find the springs I need to put on, and at my weight (240lb) it suggests an 0.54 kg/mm fork spring rate and a 11.9 kg/mm rear spring. This compares to a stock of 0.394 kg/mm and 10.5 kg/mm front and rear respectively.

Problem is, the stiffest front springs I can get are Eibach 0.47 kg/mm, 12 kg/mm rear springs are available from everyone. Is there any good way to get the front stiffer? I know jacking up the preload with spacers will only really adjust your sag. Also, if I have to run these springs, should I under-spring the rear as well? I think going from 0.394 to 0.47 in the front would make a big difference, but I don't want to throw off the balance of the bike by having the rear over-stiff.

Also, has anyone sprung 88-90 XRR forks? I kinda want to get some 91+ forks and bolt em up, but I don't want to spend the $200 for the forks and attendant parts to replace (axle, spacers, speedo drive bearings for 15 to 17mm axle swap, I'm sure no 91 forks will come up soon on fleaBay). I wouldn't mind keeping the 88 forks, rebuilding them and seeing if they're any good on dirt when sprung more properly, I understand that 88-90 springs drop into 91+ forks. Springs first, damping 2nd, right? Thanks!

Share this post


Link to post
Share on other sites

What kind of riding are you doing?

I have .47 in my CR forks and they are nice for ME at 240lbs.

But I'm a single track/putt putt guy.

If you are a desert racer type, then maybe you need stiffer.

The recommendations vary a lot from the different sources. I've got an 11.0 on mine and think it's perfect.

Share this post


Link to post
Share on other sites

Mainly Single track, hillclimb/decline, and a tiny bit of MX. I can't tell if the rear is way soft but the front feels awfully soft after riding more modern stuff. I won't be able to order springs for a couple weeks but I'd definitely like to get an idea of what to expect, I can't really afford trial and error here!

Share this post


Link to post
Share on other sites

In general most all XR's are softer (need more help) up front than in back.

Lots of guys that change the front end leave the rear alone. Up to 200lbs or so.

You're going to like 11.0-12.0 a lot compared to stock at 240lbs, same with the .47 fork springs. Don't sweat the "nth degree", those are all close and will work just fine.

If the fork needs more help you can play with oil levels and viscosity, but you may well be pefectly happy with just the springs.

To me 12.0 would be too stiff, but motocross jumps are something I do not do, so it might be needed for you.

I've ridden bikes for 40+ years and it's only in the past 5 years that customizing your suspension for your weight has become something that many riders OTHER than racers do.

Rode many bikes for many years with the stock suspension and never thought a thing about it. :smirk:

Share this post


Link to post
Share on other sites

Thanks a bunch! My 0.47Kg/mm springs just came in, I'm gonna replace the fork seals and springs tonight. I got some 15W fork oil to go with it, I've heard you need to go pretty stiff to get decent damping with damping rods and stiffer springs. I think I'm going to get an 11.5 Kg/mm spring in a few weeks. The local OHV parks here are too wet for my taste, especially when I'm changing the suspension around. I figure I'll get the spring on, ride it for a bit and then see if I want cartridge emulators or go to newer XR600/XR650L forks.

Share this post


Link to post
Share on other sites

I just replaced the fork seals and springs on my bike. It turns out the bike's previous owner had thrown out the short springs in my forks. The front end is now very stiff, feels about as stiff as my brothers 02 CRF450R. Does anyone know approximately what the spring rate would be with no short spring and .47 kg/mm spring in there as well?

Share this post


Link to post
Share on other sites

Problem is, the stiffest front springs I can get are Eibach 0.47 kg/mm, 12 kg/mm rear springs are available from everyone. Is there any good way to get the front stiffer? I know jacking up the preload with spacers will only really adjust your sag. Also, if I have to run these springs, should I under-spring the rear as well? I think going from 0.394 to 0.47 in the front would make a big difference, but I don't want to throw off the balance of the bike by having the rear over-stiff.

You can actually get stiffer springs than that. I just went through this a month ago. When I called Race Tech, they said .47 was the stiffest available. However, in the past I had purchased heavier. I finally called Ryan at Eibach and he gave me the # for .48, .49, and .51s. I ordered a set of .49s not a month ago, got them w/o issues.

Call Eibach and persist, they have them.

BP

Share this post


Link to post
Share on other sites

I'm thinking more about the rear now, does anyone have experience with the 36mm showa shock on the rear of the 87-90 xr600's? Can these be revalved pretty well, or should I get a newer 44mm xr600/650l shock or an aftermarket one for this guy? Is it worth springing? I understand that the XR6 has a pretty odd rocker ratio, making some aftermarket shocks impractical.

Share this post


Link to post
Share on other sites

At 240lbs you NEED to change the spring. For most guys that's enough.

Recharge the nitrogen and go ride.

Not near as much difference to be gained messing beyond that (compared to the front), short of buying Ohlins or Works Peformance or other $500+ shock.

Racers and go fasters get the shock revalved but that's a lot less common than tweaking the front.

I bought a Works performance shock this winter, so maybe I'll have a different opinion in a month or so when we can start riding for real. ( with 3 brand new Eibach springs to pick from!)

600's did not come with 10.5 stock, either 9.0 or 9.5, don't remember which. I could live with 10.5, but it's way soft as is (stock).

Share this post


Link to post
Share on other sites

Ps- Pretty sure I have 10.5-11.0-11.5 springs.

Pretty sure I'll not use the 11.5 at all if interested PM me. Possible that I have 10.0-10.5-11.0, I'll have to check.

Very pretty though. :smirk:

Share this post


Link to post
Share on other sites

Thanks, I'm going to order up an 11.5 kg/mm spring from racetech soon. I don't think the springs you've got for your XR650L would fit--I'm pretty sure that's got a 44mm body and my 88 XR600R has a 36mm shock body. I'll let you know how it goes, but I'm excited to have a properly sprung dirtbike.

Share this post


Link to post
Share on other sites

I have bought many many sets of heavy springs from many many different places over the years. The best springs I have ever bought, without a doubt, came from Cannon Racecraft in Oklahoma City, Oklahoma. I have a set on my 525 KTM. In about 10,000 miles of riding they have not sagged any that I can tell. Other springs I have used needed to be replaced every couple of years. I bought set for my 650L. I weigh 275 and wanted springs to hold up me and some luggage. I told them that, and they calculated the rate I needed and I am very satisfied with what I have. I think the forks springs are .54, don't remember what the shock is. -From my personnel experience--works performance springs were WAY too soft, race tech, atk/ eibach springs seemed too harsh in the first few inches, progressive springs are too soft at first if you are much over 200 lbs. EVERY set ( 5 or 6) of eibach springs I bought had forks springs that were at least 5 mm different in length, some were more than 10 mm different.

Share this post


Link to post
Share on other sites

So, I rebuilt the front forks, put 15W fork oil in them along with Eibach 0.47 Kg/mm springs. I didn't adjust for proper front race sag yet, I think I need to wait until I have the right rear spring before that will be correct. Anyways, I went on a little 40 mile urban/hills dual sport ride here in Oakland and the bike feels a hellova lot better. My bike rips with a full exhaust and the cam on it too. I do need that rear spring badly, the extra weight and travel it's taking is accentuating how terrible my kenda rear tire is.

Anyone know any good ds rears, like between 60/40 and 85/15 street/dirt? I like the Avon Distanzias and IRC GP110s, those both stick really nicely and aren't too embarrassing on trail. I used to have GP110s front and rear, but I replaced the rear with that Kenda 671 cause I couldn't afford the IRC at the time. Don't get that tire, it's better on the dirt than on road, and it's awful on both!

I called up racetech for a 11.5 or 12 Kg/mm rear spring and they're out and need to get some made up. I just want to get the thing right! :smirk:

Share this post


Link to post
Share on other sites

How much from Racetech?

Cannon quoted me $130+ shipping about a year ago. Any rate and color you want.

Share this post


Link to post
Share on other sites

I've got a brand new 12.0 Eibach for a XR650L, and I'm looking for a 11.0 if anyone has one and wants to trade. PM if interested...

Thanks ~ Ken

Share this post


Link to post
Share on other sites

Race tech wants $115 but it might be more or less for your bike. I have that little rear shock on my '88. They don't have any in stock though, and I'm waiting on them to give me an email saying about when I can expect it.

Share this post


Link to post
Share on other sites
Race tech wants $115 but it might be more or less for your bike. I have that little rear shock on my '88. They don't have any in stock though, and I'm waiting on them to give me an email saying about when I can expect it.

Thanks JT. I'm under the impression that the stocker is actually between 10.5 and 11.0. Need to get one in hand to measure it. If you're intersted I have a brand new Progressive Suspension spring for your shock in stock, P/N 1187-20GT. It's your's for $20 shipped should you want to try it. For that price it may be worth a try...

~ Ken

Share this post


Link to post
Share on other sites
Race tech wants $115 but it might be more or less for your bike. I have that little rear shock on my '88. They don't have any in stock though, and I'm waiting on them to give me an email saying about when I can expect it.

I was just asking so you could compare to Cannon, they make them to order so I assume you'd have it in a week. (What they told be then)

Share this post


Link to post
Share on other sites
Thanks JT. I'm under the impression that the stocker is actually between 10.5 and 11.0. Need to get one in hand to measure it. If you're intersted I have a brand new Progressive Suspension spring for your shock in stock, P/N 1187-20GT. It's your's for $20 shipped should you want to try it. For that price it may be worth a try...

~ Ken

I bought one of those this past summer off ebay, new in the package. Works much better than the stocker on my 85 XR350. (narrow body shock too)

Believe the packinging said it went from 9.5-12.0 (progressively wound spring is what Progressive does).

If you can find a straight rate for your bike, I think that is always the prefered, but if not the Progressive is a pretty nice alternative. FWIW

I paid $35 for mine and I don't think I'll bother buying a new straight rate spring for the bike, works good enough for me. (trail riding, dual sport)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×