The Honda PCX / Forza / ADV150 / SH Forums

Not test driven yet but looking very good





Next in line, YSS PD Fork Valves

Almost ordered a pair today, would like to hear what you think of the ride with the new shocks vs. the OEMs. Looks nice!

Dit a short test run (shitty weather) with the new rear shock's, well they feel a lot firmer without the irritating ass bump's you normally get when you hit a threshold, was a short test but I am convinced that the rear suspension is much improved over the stock ones

Excellent. More pictures when you can?

Preparation for the YSS PD-Valves (type 265 (26,5mm) for the Forza 300).

Regarding the manual the PD-Valves have a preset preload of 2-turns (for lighter riders) I weight 93Kg so I guess a preload of 3 turns will be better for me.

For the fork oil, I have chosen 15W.






No idea how it work's but for the interested I shoot some pictures of a dismantled YSS PD-Valve.














Allan screw turned in by hand until the spring fits play-free without any pressure, then in my case turnt in 3 turns with an Allen key.




Lock-nut fastened without turning the valve and Allen screw.




Finished with a 3 turns preload.

One fork leg is ready, filled with 200cc 15W.

The finished leg feels totally different than the one that's still original, it almost feels like the original fork setup has only a spring without any form of damping

Excellent documentation Mario!

The Forza's front suspension has always seemed as though it was designed for "perfect" roads instead of REAL roads and the worse jolts always involve the front end.

I'm interested in seeing how the tunable fork valve works....
you do the the R&D and tell us where to set it?

Thanks for all your hard work for the Forza geeks!!

I just got the same shocks, need to put them on this week. Anything out of the ordinary for the install or just a straight forward bolt them on? Do I have to take off any plastics or can I remove them completely from the outside of the scoot?

Thanks BRed, happy to help in any way I can.

BRed wrote:Excellent documentation Mario!

The Forza's front suspension has always seemed as though it was designed for "perfect" roads instead of REAL roads and the worse jolts always involve the front end.

I'm interested in seeing how the tunable fork valve works....
you do the the R&D and tell us where to set it?

Thanks for all your hard work for the Forza geeks!!

There is no need to dismantle anything other than the old shocks, and they are a perfect fit including the little offset on the left shock.

Kompact wrote:I just got the same shocks, need to put them on this week. Anything out of the ordinary for the install or just a straight forward bolt them on? Do I have to take off any plastics or can I remove them completely from the outside of the scoot?

Mario wrote:Preparation for the YSS PD-Valves (type 265 (26,5mm) for the Forza 300).

No idea how it work's but for the interested I shoot some pictures of a dismantled YSS PD-Valve.

Great documentation pictures Mario - as always.

For those who are interested, a bit of a read up with a link to the original developer of the cartridge emulator in my original topic describing my installation on the PCX.
http://hondapcx.org/viewtopic.php?f=9&t=4877

In case there would be a need I can describe each part of the valve operation. It is actually a very nicely designed simple but effective solution to change the compression damping characteristics of a conventional fork to separate slow damping from quick.

I'm sure you'll like your transformed ride Mario.

Thanks Oyabun,

And yes please tell how it works, it will give me an idea what to change when I need some adjustings.

Oyabun wrote:

Mario wrote:Preparation for the YSS PD-Valves (type 265 (26,5mm) for the Forza 300).

No idea how it work's but for the interested I shoot some pictures of a dismantled YSS PD-Valve.

Great documentation pictures Mario - as always.

For those who are interested, a bit of a read up with a link to the original developer of the cartridge emulator in my original topic describing my installation on the PCX.
http://hondapcx.org/viewtopic.php?f=9&t=4877

In case there would be a need I can describe each part of the valve operation. It is actually a very nicely designed simple but effective solution to change the compression damping characteristics of a conventional fork to separate slow damping from quick.

I'm sure you'll like your transformed ride Mario.

Only possibility is to play with the oil viscosity and spring preload on the valve.
Will do the throughout explanation sometime during the week when I'll be logging in from a computer not just my smartphone and will be able to do some picture editing to point out parts of the valve.

If you are the person you look like based on your activity so far, then you have already went for a ride and tried the new front end. I'm really curious how did you liked it. ;-)

Sorry, still only one leg is finished, do to my work (overtime) I think next weekend.

Done and test driven it, it's for sure a big improvement over the stock front suspension

But to be honest, it's not (yet) as good as the rear YSS shocks, the rear shocks are firmer and the damping is spot-on.

I think thicker 20W oil (less rebound) and one (maybe two) turn more on the valve spring preload (less diving under braking) brings it more in balance with the rear shocks, but this
is all a guess, don't know the effect of thicker oil on the valve, so maybe only thicker oil is the key.

But for I change anything I want to make more Km with this setup, with the weather over here that can take a while

Glad to hear you like it.
It seems that I really have to write that explanation. ;-)

A suspension does get firmer from a heavier spring - damping have less to do with that.
Compression damping characteristics can be separated with your new fork springs.
- slow damping (like slow compression under gradual braking) is through a small hole on the disk held by the preloaded longer and thinner spring. It is adjusted by the fluid viscosity. You might want this baseline as medium strong damping to iron out the small irregularities of the road.
- fast damping ( like quick compression caused by a ridge, or a pothole) is set by the fluid visit osity AND the spring preload. You want this to set relatively soft to let the suspension soak up the sudden hits.
Rebound damping is not taken care of by the valve (the large diameter spring and disk is releasing all the fluid on the rebound stroke) but handled by the original small valves on the damping rod. It is adjusted by the fluid viscosity only.
As you see, oil viscosity is a baseline for the damping and certain things (like rebound ) are still fixed. Therefore that has to be adjusted first. It has to be enough so that after a hit it does rebound slower, but not too much because then the suspension would pack down or gradually compress over a series of small hits and not able recover in time to get the next.
So first of all, if you feel that the front is soft compared to the new rear suspension, you might want to change the fork spring to a 10-15% heavier one as a start. I would not go over 20% for sure.
Then I'd go for a slightly heavier fork oil. God to know, that in case you use the same brand you can mix them proportionally - so using 50-50% 15w and 20w you end up at 17.5.
Hope this helps.

Mario wrote:Done and test driven it, it's for sure a big improvement over the stock front suspension

But to be honest, it's not (yet) as good as the rear YSS shocks, the rear shocks are firmer and the damping is spot-on.

I think thicker 20W oil (less rebound) and one (maybe two) turn more on the valve spring preload (less diving under braking) brings it more in balance with the rear shocks, but this
is all a guess, don't know the effect of thicker oil on the valve, so maybe only thicker oil is the key.

But for I change anything I want to make more Km with this setup, with the weather over here that can take a while

Do you advise against to mount the Yss rear shocks and leaving the front suspension stock?

Like I said, I first make some miles with this setup to get a better idea of what I have now, but if there are guy's who want to do this upgrade IMHO they can set it up a bit higher for starters.

Oyabun wrote:Glad to hear you like it.
It seems that I really have to write that explanation. ;-)

A suspension does get firmer from a heavier spring - damping have less to do with that.
Compression damping characteristics can be separated with your new fork springs.
- slow damping (like slow compression under gradual braking) is through a small hole on the disk held by the preloaded longer and thinner spring. It is adjusted by the fluid viscosity. You might want this baseline as medium strong damping to iron out the small irregularities of the road.
- fast damping ( like quick compression caused by a ridge, or a pothole) is set by the fluid visit osity AND the spring preload. You want this to set relatively soft to let the suspension soak up the sudden hits.
Rebound damping is not taken care of by the valve (the large diameter spring and disk is releasing all the fluid on the rebound stroke) but handled by the original small valves on the damping rod. It is adjusted by the fluid viscosity only.
As you see, oil viscosity is a baseline for the damping and certain things (like rebound ) are still fixed. Therefore that has to be adjusted first. It has to be enough so that after a hit it does rebound slower, but not too much because then the suspension would pack down or gradually compress over a series of small hits and not able recover in time to get the next.
So first of all, if you feel that the front is soft compared to the new rear suspension, you might want to change the fork spring to a 10-15% heavier one as a start. I would not go over 20% for sure.
Then I'd go for a slightly heavier fork oil. God to know, that in case you use the same brand you can mix them proportionally - so using 50-50% 15w and 20w you end up at 17.5.
Hope this helps.

They are both a great improvement on there own, but if you do one you want...........

kar120c wrote:

Mario wrote:Done and test driven it, it's for sure a big improvement over the stock front suspension

But to be honest, it's not (yet) as good as the rear YSS shocks, the rear shocks are firmer and the damping is spot-on.

I think thicker 20W oil (less rebound) and one (maybe two) turn more on the valve spring preload (less diving under braking) brings it more in balance with the rear shocks, but this
is all a guess, don't know the effect of thicker oil on the valve, so maybe only thicker oil is the key.

But for I change anything I want to make more Km with this setup, with the weather over here that can take a while

Do you advise against to mount the Yss rear shocks and leaving the front suspension stock?

Great stuff, Mario. I wonder, for the perfect front-end set up, would you consider progressive springs, or do you think that the PD valve and different oil are enough?