VF500 YSS cartridge emulators

I bought a pair of these recently and would like to know if anyone has successfully installed them.

When I offered them up to the damper rods I noticed that the non TRAC side was 7mm higher. When I offer up the spring to the emulator I noticed it only contacted the emulator on its outer edge. It would appear that some form of spacer come adaptor is missing to both correct the 7mm offset and provide a decent seat for the spring to emulator.
I notice the RACETECH version has some form of spacer which probably addresses this issue.

I have contacted RACETECH to see if they have a UK supplier as I reckon the YSS kit is going back

 

It's been A LONG TIME since I installed the RT versions on my 500 race bike. But I don't believe there were spacers needed. I have read about the spacers in their literature, but have never seen them. One of my kits (for a 1000 I think) noted it was needed, but it did not come with one, or need it.

What YSS part number was the kit you received?

I have successfully installed the YSS versions on a CB-1. They sat ON TOP of the damper rod, not down inside.

 

Fork Emulators PD238.

The Racetech install guide covers the TRAC damper rod difference but the ones they show in the pics are not VF500 versions. I assumed a
use of a spacer/adaptor as that is the only way to address the 7mm difference in length, unless you ignore it and have differing spring pre-loads.

 

Different preload spacers for the same pre-load.

The YSS valves I bought for a 1986 VFR (not installed yet) that has 37mm forks as well, was PD290. Don't know why they would make a different version for the 500. I did remove mine from the packaging and they perfectly mated with RT springs I have for it in the same way as every other kit has, RT or YSS. The RT springs are the same for the VF500 and VFR750. You should not be just on the outer edge of the Emulator with the spring.

That does seem odd.

 

Looks like I better crack some VFR forks apart. And dig out some 500 damper rods. I don't want to go thru this in the future when I do a 500 ( and the VFR). The RT products have gotten very expensive in the last year or so.

 

Captain, missed your point on the fitment. If the YSS ones were the same (flush with the outer edge of the rod) the spring to emulator problem would not exist, or the 7mm difference. I did speak to a YSS tech support guy from the supplier and he told me they are correct and should work fine! But I reckon he is using the YSS catalogue is incorrectly suggests the PD238.

 

I noticed the FT500, which also has 37mm forks, also lists PD238. So it's not a one off mistake in the catalog. Doesn't mean it's not wrong.

But I have NEVER had the valves go down in the damper rod cup. Doesn't make sense. Seems it would be seriously impeding flow.

I have done 7 sets of damper rod forks now.

I will 100% be verifying the 290 to a 500 fork. And I'll just install VFR damper rods in a 500 fork if needed to use the 290. When drilled out, it's just a platform for the valve.

 

Give me a day or two to get out one of my "MISC FORK" boxes where I have some 500 damper rods already extracted.

Also, the different height damper rods might be compensating for a different assembled height due to the fork differences, and end up using the same preload spacers. And valves should be on top as previously discussed.

500 fork springs/same length spacers don't stick up higher than the other when installing caps.

 

The dimensions for the 290 seem to compensate for your problem. Other 37MM forks the 238 were initially designed for may use damper rods with smaller cups,

PD290
Outside diameter 29mm
Diameter for piston bore in the fork: 21mm
Total valve height: 16mm

PD238
Outer Diameter 23.8 mm
Diameter for Piston Bore in Fork 13.8 mm
Total Valve Height 14 mm

 

The PD290 would certainly seem to be the better fit for the fork tube. The 21mm damper rod shoulder is a bit loose as the rods internal diameter (cup) is 24mm, although I dont think this matters too much. Im going to swap out the PD238 for PD290 and see how it goes.

 

I now have the PD290 valves, and they sit on top of the 500 damper rods in the same way the pic provided of your CB1 Captain. I bought the YSS springs too, and they look very similar to the OEM versions, including the length.
The YSS valve guide is somewhat generic, so does not cover anything relating to the TRAC system. The instructions on oil level mention adding the valve, then oil to the leg as per OEM (without spring). It then goes onto to state adding the valve and to check the oil level before adding the spring! A bit contradictory.
Unless anyone can give me a better steer, I am going to add the OEM oil level specific to each leg (without valve), then add the valve, spring and cap it off.

In respect of the YSS springs, they come with no info at all, so I shall install the tightly coiled end first.

 

I have used Racetech emulators in the past and fitted some to an 86 750 with TRAC a couple of years back.

The RT instructions are quite specific and recommend drilling the damper rods so that the compression damping is effectively removed; the emulator takes over that function and in doing so removes the TRAC effect.

Regarding fork oil height, the aim is to end up with a known air-gap between the top of the oil and the top of the fork tube, and that can only be done without the springs and with the fork full compressed. On my 750 RT recommended 140mm air gap and 15W oil. The oil height can be adjusted to improve bottoming resistance if needed; more height = smaller air gap = greater compression when the fork dives = higher resulting air pressure when compressed = more bottoming resistance. I would certainly drop the emulators in before setting the final oil height.

The oil weight is used to tune the rebound to your liking, and the adjustment at the emulator (spring tension, spring rate, bleed holes) allows you to tune the compression damping to your preference (and to match the oil viscosity).

Regarding spring orientation, the end of the spring may be slightly tapered and may be a better match for the top of the emulator or the bottom of the spacer/washer. As long as the end can't slip inside another fitting the orientation isn't otherwise important .

 

Everything Terry said and...

RT instructions state to remove the circlips, washers and spring on the TRAC fork to disable and I do that when I convert to Emulators on TRAC forks. It is no longer needed/wanted.

 

I have removed the TRAC valve shims and drilled the 4 x 8mm holes in each damper rod. Thats opening up the non TRAC rods 4 holes from 7mm to 8mm, and adding 4 new 8mm holes in the TRAC rod. So the TRAC rod has 6 holes: The original 2, plus 4 new ones. the Non TRAC rod has just 4 holes. This aligns with the instructions. I am however of the view that if the holes are eliminating the damping effect, then adding a few more wont hurt, so at least I end up with 6 in each.
The YSS instructions are printed so small that I had to photograph and enlarge it to read properly!

 

I would also go 6 each, and I do when I perform this step. You can't have too much flow to the Emulators, but not enough is defeating their purpose. Now is the time.

 

It's interesting that even their instructions state (and diagram shows) that the valve goes ON TOP of the piston "and must cover it completely". Not sit down inside.

I wonder how many 500 owners have installed the 235?

 

Indeed captain. Even the YSS guy at Firefox Racing said it was ok….and should work!

Thanks Terry, Ill filling oil based on height rather than capacity.

 

So got it back together and just completed a 100 mile round trip of varied roads. Front end is much improved, especially under braking. As I installed both YSS emulators and springs, its impossible to gauge each independently. A worthy upgrade. Probably my imagination, but the back end felt more assured even though its still running a stock unit.
Its worth noting that the YSS springs are the same length as standard, so with the addition on the emulators, it adds 16mm of preload to the springs, which doesn't sound much but made putting the cap nut back on really difficult.

 

That's great news. Typically approx 20mm of preload is standard for the correct rate springs, so you me be a little heavy in that department... but if it works and feels good, awesome.

After a loop like that with everything cycled, you might consider verifying your sag numbers... but again... sounds like you are happy.

So glad you got it figured out.