Jump to content
Sign in to follow this  

Value of Suspension Work

Recommended Posts

I have a '99 XR400R. I am telling my self that before the spring season I am going to do fork oil and seals. While I am working on it I figured I would actually set the sag, as I hear its one of the most important things you can do to set up your bike. I am wondering how valuable it is to go beyond oil, seals and sag?

 

I used the racetech.com spring rate calculator and they say the bike should have a .41 and I should have a .47. (About $130 for front springs)I understand what these are measuring, but I don't know how much that is going to effect the way the bike performs and if I would be able to notice. I am excited to maintain this bike, but its no spring chicken and at some point I would rather start saving for a newer bike with more modern suspension that spending hundreds of dollars to make the XR something it is not. 

 

What are folks thought on this?

 

-Matt

Share this post


Link to post
Share on other sites

I'm curious as to how long you've been riding it without setting the sag.

 

Recommended .47 springs suggest you've got some weight to you. So what is it?

 

The stock suspension is well known for being unbalanced, front to rear. With the fork springs being too light or the shock spring being too stiff. Fork springs that are too light for your weight will make the front end harsh. Swapping in proper wt springs for your weight, even tho they are of a heavier spring rate, will make the front end more plush.

  • Like 1

Share this post


Link to post
Share on other sites

Suspension correctly configured is the number one most important item you can choose to dial in. It will make you a better, safer (less fatigued), faster rider and you will ultimately spend less money on repairs to it and your body in the long run. It's also amazing how much horsepower you can find in suspension! 😉

  • Like 2

Share this post


Link to post
Share on other sites

I weigh about 175lbs. Usually a little less in the summer. I have ridden the bike almost 2 years. The guy I bought it from was a similar weight, but a bit taller than me. I imagine he set it up. He worked at a dealership and had a couple other mods done to the bike. Either way, it's he middle of the winter here in Utah and I probably won't be riding for a bit so I have time to finally do this.

Is there a way to measure sag in the front end, like in the rear?

Edited by matt_israel

Share this post


Link to post
Share on other sites

.

Is there a way to measure sag in the front end, like in the rear?

 

Yes. But you'll need to be sure the rear sag is set correctly first. Because how much the rear end sags effects how much weight is transfered to the front suspension and any measurement you take.

 

With the rear rider sag set between 90 - 105mm, you're looking for 35 - 50mm of front suspension sag. After you get those in the ball park, check the free sag of the rear (bike under its own weight, no rider). You're looking for 15 - 25mm.

 

All these are recommended ball park figures. They can be fudged a bit depending on the kind of ride and handling you're looking for.

Edited by Trailryder42
  • Like 1

Share this post


Link to post
Share on other sites

Ok. I will service this stuff and see how close I can get the suspension set to 'recommended.' Any thing tricky or that I should know about doing seals and oil in the front and rear? Do i have to do the rear too?

Share this post


Link to post
Share on other sites

Changing the rear shock oil is a specialized process that not many people have the equipment to take care of. You're better off having the shock done by a shop. You don't "have to" do the shock, but it's oil is 16 years old if it's never been changed, so it would definitely benefit from at least an oil change.

 

There are tips for doing the front and for not damaging the new seals when you install them. Search YouTube for some videos.

 

Also try to find a shop manual for you to go by.

 

For your '99 model, stock fork oil height is 3.9". You can set the height with a homemade tool made from a turkey baster, like mine shown in the picture.

 

The bottom fork bolt comes out easiest with an impact wrench, electric or air powered. There are other tricks tho if you don't have access to those. YouTube videos should cover that.

Tool 1.jpg

  • Like 1

Share this post


Link to post
Share on other sites

My buddy has a 2003 XR250 with full Bruce Triplett suspension including his famous "Terrain Tamer" forks and words can not describe how good it is, especially the forks.  I have a Fox Podium X shock and Bruce Triplett forks on my CRF230 and the bike is simply amazing.

 

Keep in mind with stiffer springs comes more rebound and the need for more rebound control, which stock XR forks severely lack.

  • Like 1

Share this post


Link to post
Share on other sites

.47 fork springs sound a little stiff for 175lbs. I am 195 before adding gear and I have .44 or .45, can't remember. 

Edited by YHGEORGE
  • Like 2

Share this post


Link to post
Share on other sites

Thanks guys. I love this resource. I will start with the oil and seals in the front end and setting the sag in the back and see how she rides. I haven't noticed anything too bad with the way it is set up now. I messed with the clickers once in the front and immediately turned it back to where it was at. Maybe its pretty close already.

Share this post


Link to post
Share on other sites

If it ain't broke, don't fix it! :ride:

That's the catch with the XR400 suspension, they were broke from the factory.  About four years back I got some excellent advice from Trailryder42 among some others on this site and I sent my forks and rear shock to precision concepts in southern Cal. They customized my suspension based on my weight and riding style and it is not the same bike. I love it now and it was the best 900 bucks I ever spent on a bike. I've been riding it for ten years or so and I wish I had done it sooner. It rides like my sons CRF except for the extra weight.  I am an excellent mechanic but I let the suspension experts do my suspension work. Good luck and good riding, Dave

Edited by Rediron
  • Like 1

Share this post


Link to post
Share on other sites

Matt,  Stock fork springs are fine.  I weigh about 190lbs. I run max oil level and Maxima 5wt RFF.  Remove 3-4 shims from the delta valve.   Stock shock valving is good with good shock oil.  Set the rider sag at 105-107mm .  I know that is more than normal but the bike handles better and more balanced that way. Drew Smith talked me into trying that and it works on THIS bike. Normal sag with this much travel is 100-103mm but it will cause head shake and a high rear end. Also Try the Dunlop AT81 tires. A bit lighter and a shorter rear tire than my other favorite the MT16 Pirelli.  Run the 110/100X18 and 90/90X21 .  Race Tech's spring calculator is WAY OFF for offroad riding. It maybe closer for MX / SX but I think it is still too stiff. They WANT to sell you springs that you really don't need. Also bleed the front forks before every ride.

  • Like 3

Share this post


Link to post
Share on other sites

We use .42/.43 springs for 160/185 pound rider (Don't go racetec springs)    2 1/2wt oil. 6 shims remove. Rear shock revalved,plush on start,then gets stiff.Stock spring. This set up for all around trail riding,not racing.

  • Like 1

Share this post


Link to post
Share on other sites

I am still waiting to crack in to these things. Winter just keeps coming here in Utah, and the ski conditions are better than the garage 'working' conditions. Might have to wait a few until it warms up a little more.

Share this post


Link to post
Share on other sites

We use .42/.43 springs for 160/185 pound rider (Don't go racetec springs)    2 1/2wt oil. 6 shims remove. Rear shock revalved,plush on start,then gets stiff.Stock spring. This set up for all around trail riding,not racing.

What brand spring do you use? Correct length? Thanks.

Share this post


Link to post
Share on other sites

The best so far (there all too short) Eibach.I would try cannon race craft springs,ask them overall length. Since we have so many xr4s,We could compare.Performance on springs.Lets just say.I'm not happy we had to send back.All springs from Racetec. Cannon springs are very good,problem is.We dont have them in our XR4s.In our other bikes good.

Share this post


Link to post
Share on other sites

So, I have a couple unopened bottles of Showa SS-7(I think) that I got when i purchased the bike. Does this stuff go bad just sitting on the shelf or does it need to be in a fork getting worked to degrade? After checking on the rocky mountain atv site it looks like they also have SS-8 fork oil available for stiffer suspension/heaver loads. Do folks think I would be ok with the standard SS-7 or should I go with the 8 in leu of not having stiffer springs?

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  

×
×
  • Create New...