Upgrade to Fork Valves?

[Sparky84]

Thinking of installing RPM Fork Valves they seem like they will soften/smooth up the ride but I have a few questions before going for it.

If I install Fork Valves does that mean I need or should do rear shock?,
from what I've been reading that the rear feels quite underdone after front has been upgraded.

After Fork Valves does that mean if I want to up front tyre to 17/18" it's been a waste of money?

Anything else needed to do if Valves are installed

Cheers Alan

[4everFJ]

If your rear shock is the original, then you should definately upgrade it, no matter what you do - or don't do - to your front suspension.

YSS makes a good quality rear shock for the 1100, that is afordable.

[Bill_Rockoff]

The cartridge-emulating fork valves do a good job providing you with different damping for high-speed (bumps) and low-speed (braking/cornering) compression events. This will let you run heavier front springs than stock; it will handle better, and the better damping will let it ride better. I think the stock springs are 0.65 kg/mm, but I forget if that's right and I forget whether or not it varies by year. My aftermarket springs are 1.1 kg/mm, which is possibly a touch too heavy for my average adult male height/weight (1.05 or 1.0 might have been better) but it's still amazing compared to stock.

While the forks are apart for the installation of these, it will be trivially easy to change the springs while you're at it. And the valve manufacturer (RaceTech? Traxxion? RPM?) will have advice for you on what weight of fork oil / how much of it you should install, so ideally you'd want to change the fork oil too.

The new fork springs and fork oil will cost about as much as the fork valves. In the US, this will add up to the cost of filling the FJ's tank about 35 times, at the USA's relatively-cheap fuel cost, or about 1-1/2 times the cost of having a shop replace both tires on your bike. It's worth it, and it's worth doing it all at once so you don't repeat your work.

A good rear shock will give you the same benefits - stiffer spring rate that is more appropriate to the bike's weight, along with better damping to allow proper response to bumps without letting it wallow under cornering loads. These are more expensive, maybe 3-1/2 to 5 times the cost of the fork valves (so double to triple the cost of your fork upgrades) but it will include a rear spring.  It's an easier installation than the fork valves, though, and the result is maybe even more profound and noticeable since the rear shock carries a lot more of the rider's weight than the forks do. Also, a good aftermarket shock will let you raise the rear ride height independently of the spring preload adjustment, which makes an FJ much easier to turn into a corner.

Together, upgraded suspension at the front and the rear improves both the ride and handling; it's as big a difference as going to really good tires. I think Avon radials are available for your 16" wheels, which will get you 90% of the way to "really good tires," so you can maybe hold off on going to lighter wider wheels in 17" diameter.

I'm not aware of any bolt-on brake or wheel upgrades to the early FJ forks. The '88 and later forks are set up for different calipers, and for these bikes the modern aluminum calipers from an early R1/R6/FJR/FZ1/FZ6 are a direct fit.

I'm using 1.1 kg/mm springs, either RaceTech or Traxxion valves (I forget) and heavier fork oil (I forget which and how much; Traxxion Dynamics did it when they rebuilt the forks.) In back, I have a Penske shock. My bike is an '89 so it came with a 17x3 front wheel; it's narrower and heavier than modern wheels, but it carries any top-shelf tire just fine (they are all available in 120/70-17.) My rear wheel is a 17x5 from a YZF600R, with the sprocket carrier and spacers/brake-stay machined down by Joh Cain to fit where the FJ stuff fits.

With all these upgrades, my FJ1200 is a magic carpet on rough roads and it's easier to corner hard than my Ducati 998; it corners and stops like a modern sportbike. In fact, even with 115,000 miles on it, the FJ1200 seems to be everyone's preference over the 998, and it just might be faster on real roads.

[ribbert]

Thinking of installing RPM Fork Valves they seem like they will soften/smooth up the ride but I have a few questions before going for it.

If I install Fork Valves does that mean I need or should do rear shock?,
from what I've been reading that the rear feels quite underdone after front has been upgraded.

After Fork Valves does that mean if I want to up front tyre to 17/18" it's been a waste of money?

Anything else needed to do if Valves are installed

Cheers Alan

If you do the forks and the leave the rear shock the bike will still be better.
Some folks just observe that it makes the short comings of the rear shock more obvious, it doesn't create a need to do it.
The benefit of doing your forks is not related to wheel size and any improvement you enjoy will be carried over to the 17" wheels.
You will need new springs to go with the valves.

Noel

[andyoutandabout]

I had it the other way round. The bike came with a fancy fox rear shock and a squishy standard factory front. Certainly a night and day event by just upgrading the front springs. Fast forward a few years and the RPM valves and a resprung/ revalved rear have transformed the ride.
Suspension mods are a shrewd investment

[Mark Olson]

Thinking of installing RPM Fork Valves they seem like they will soften/smooth up the ride but I have a few questions before going for it.

If I install Fork Valves does that mean I need or should do rear shock?, no, you will still have a stable ride.
from what I've been reading that the rear feels quite underdone after front has been upgraded. you are just able to feel it more

After Fork Valves does that mean if I want to up front tyre to 17/18" it's been a waste of money? no, you will use the fork valves no matter what you do in the future. they fit all FJ forks years.

Anything else needed to do if Valves are installed rebuild your forks with new bushings and seals and install new fork springs. There will be some drilling done to the inside part of the fork leg that will disable the anti-dive.

Cheers Alan

The instructions for installation are pretty clear and you will enjoy the difference of your new valves. If money is tight you can add a pvc spacer to your stock springs to reach rider sag numbers. Then jump the chain on your rear shock to get the rear rider sag number.
There is a ton of info in the files section on suspension. You should read it to get

[racerrad8]

Anything else needed to do if Valves are installed rebuild your forks with new bushings and seals and install new fork springs. There will be some drilling done to the inside part of the fork leg that will disable the anti-dive.

Alan,

There is no drilling or other modifications required when installing the RPM fork valves.

I would recommend a rebuild of the forks. You need to ensure the taper spindle is properly installed and not upside down and wedged into the slider. The damper rods also need to be set to the same setting. You cannot do either of those things without taking the fork a parts.

Here is a link to a file that answers most questions:  RPM fork valves explained

Randy - RPM

[Sparky84]

After reading "RPM fork valves explained" Valves sound good.

I understand that the .85kg spring will be the one I need
But to clarify something about the Valve,
once I install it does that mean I don't have any adjustment due to it is already been tested and setup to suit the FJ?

At present I have White Power Springs that have been in for awhile, done since just after getting bike but they have always been a bit harsh on rough roads but were a Necessary to stiffen up front.

So these Valves and springs once they installed that's it, no other adjustment required as the Valves do all the hard work.

Also sounds like rear shock would be worthwhile doing, just have to save a few pennies and then a bit, (is it dry October?)

Cheers Alan

[racerrad8]

After reading "RPM fork valves explained" Valves sound good.

I understand that the .85kg spring will be the one I need
But to clarify something about the Valve,
once I install it does that mean I don't have any adjustment due to it is already been tested and setup to suit the FJ?

At present I have White Power Springs that have been in for awhile, done since just after getting bike but they have always been a bit harsh on rough roads but were a Necessary to stiffen up front.

So these Valves and springs once they installed that's it, no other adjustment required as the Valves do all the hard work.

Also sounds like rear shock would be worthwhile doing, just have to save a few pennies and then a bit, (is it dry October?)

Cheers Alan

There should not be any adjustment required, a lot of time has been spent getting the set up for the FJ. They are not a universal items that will fit a variety of bikes which all need different settings/springs. If you want to play with adjustment of the valve, I would have to sell you the tool to take them apart and a variety of shims to make any adjustments.

The forks spring being the proper rate and the oil level/air gap are the two critical factors.

Randy - RPM