Date: 28-03-24  Time: 23:32 pm

Author Topic: YSS PD valves  (Read 3792 times)

vinnyb

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YSS PD valves
« on: 02 April 2019, 10:06:39 pm »
 I'm hoping to finally get started on my forks before long. I've got .85kg KTech Linear springs, YSS PD Valves and a pair of damper Rods for drilling and I'm thinking of starting with 10w oil as I want a plush comfortable sports touring type setup rather than track day handling. FireFox Racing have told me that the damper rods don't need drilling but everything I've read on here and everywhere else online says they do, so having got a donor pair I might as well do it. Can anyone tell me whether I need to use the washer from the bottom of the original spring or whether the new spring should sit directly on top of the PD valve, this seems wrong to me but would the washer restrict the oil flow if it's fitted? Any other hints and tips would be gratefully accepted, thanks.

vinnyb

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Re: YSS PD valves
« Reply #1 on: 03 April 2019, 10:01:50 pm »
 My mistake, the washer goes between the top of the spring and the spacer tube so the spring sits directly on top of the damper rod. :rolleyes

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Re: YSS PD valves
« Reply #2 on: 03 April 2019, 11:28:20 pm »

vinnyb

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Re: YSS PD valves
« Reply #3 on: 07 April 2019, 09:32:19 pm »
   Drilled my donor damper rods today. I opened out the original holes to 10mm and drilled another 2 holes of 9mm above, and at 90° to them, making sure not to go above 120mm from the top (Under the lip) Can anyone who has done the mod tell me if they think it'll be enough please?
« Last Edit: 09 April 2019, 08:44:03 pm by vinnyb »

kebab19

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Re: YSS PD valves
« Reply #4 on: 09 April 2019, 08:09:10 pm »
Hello,Apologies, only just noticed this thread.It looks like you've drilled the rods out enough to overcome the original damping system. They should now be fine to fit in conjunction with the YSS valves.

vinnyb

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Re: YSS PD valves
« Reply #5 on: 09 April 2019, 08:38:07 pm »
 Hi, no worries, thanks for replying. I was going to drill the top holes to 10mm too but that would have taken them into the 120mm. As I said in my earlier post, I'm starting with 10w oil, hoping for a compliant ride, so I was going to start with 2 turns of preload on the valves to try to balance compression and rebound. What do you think? I've been told to start with a 150mm air gap before valves and springs, does that sound about right to you? Thanks.
« Last Edit: 09 April 2019, 08:47:01 pm by vinnyb »

kebab19

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Re: YSS PD valves
« Reply #6 on: 10 April 2019, 04:43:15 pm »
Vinny,Unfortunately I only ever fitted Racetech and Debrix fork emulators, never had my hands on the YSS ones so am not sure if they're exactly the same  :\ Those other Emus called for 2.5 turns of preload, along with 15w oil.  I never found them overly harsh even with the heavier fork oil.
Re: airgap - my '98 service manual says standard fork oil height is 121mm from the top of the fork (with springs out and compressed).  I am not sure if this changed for the revised forks from 2000 onwards.  If you have a 1998/99 bike, I would try reducing standard height by about 10mm (so a 130mm gap) and take it from there. Put a cable tie round the stanchion to see how much travel you're using up.

For the full lowdown on YSS valves, you could try sending a PM to 'Tommyardin' as he fitted YSS emus to his forks and got a great result.

vinnyb

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Re: YSS PD valves
« Reply #7 on: 10 April 2019, 09:03:57 pm »

 Hi, thanks for that, I'll try to contact Tommy, He doesn't seem to come on here so often nowadays, since he sold his Fazer. 
   I've got the 2003 Foxeye so the original springs are 316mm and the air gap is 132mm according to Mr Haynes. My Linear springs are 296mm and the valves are 16mm not including the recessed part that sits inside the damper rod. I would think that the valve would displace about 12mm or so, so that would make the air gap 145mm or thereabouts, so I guess that the 150mm gap is a reasonable starting point, I can add a bit more if I need to. The overall length of the new spring and valve is 4mm down on the original spring but I have the spare washers from the donor forks and the preload adjusters so this shouldn't be a problem. I need to decide whether to use 10w oil or go for 15w or maybe mix 50/50 for 12.5w. I would find slightly too soft easier to live with than too firm, it's the harshness over bad surfaces I want to get rid of. How firm does 15w make the damping? Did you use .85 (8.5) springs too?  Thanks. Apologies for the rambling post.

kebab19

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Re: YSS PD valves
« Reply #8 on: 11 April 2019, 05:54:12 pm »
I suspect you're thinking of how the standard fork setup would feel with 15w oil - i.e. harsh.   
For this conversion, the thickness of the fork oil determines how quickly the rebound damping circuit operates, while the emus control the compression aspect. When I had my old TRX850, the recommendation for their forks was to switch to 20w oil instead.   10w might be boderline light, but a mixture giving 12.5w would still work fine. You could always raise the oil level to firm things up if needed. 

Edit: According to my original Gold Valve emu installation: http://foc-u.co.uk/index.php/topic,71.0.html   the preload on the valves was only 2 full turns as opposed to 2.5 turns on the debrix emus. For a more squishy front-end you might want to stick with only 2 full turns of preload.
Fork springs - yes, I used 0.85kg/mm springs (and have the smae now in my 1000). I'm currently around 12 stone if that helps.


vinnyb

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Re: YSS PD valves
« Reply #9 on: 11 April 2019, 07:29:39 pm »

     Thanks for all your help. Having done the mod yourself, if you feel that 15w would be the best option for a comfortable, controlled, firm but not harsh ride I am going to go with to start with that and 2 turns of preload and adjust from there if I need to. I know the chances are that it's not going to be spot on first time but I need to start somewhere. I'm around 12½ stone and was a little worried that the spring rate would be too firm for my weight but they seem about right from what you've told me.
   How did you hold your front end up? Is it ok to support it on the exhaust with blocks of wood or is it likely to damage it?
          Thanks again.
« Last Edit: 12 April 2019, 05:15:58 am by vinnyb »

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Re: YSS PD valves
« Reply #10 on: 12 April 2019, 01:44:04 pm »
Hi Vinny,I would probably still opt for the 15w oil: using 10w might cause the forks to rebound back up too quickly, unsettling the bike.  I suspect you think it'll need a lot of tweaking, but you might be pleasantly surprised - providing the valve's preload is set up just right for you, you may not actually need any adjustment bar possibly adding a little more fork oil to each leg.
That spring rate should be about right for you: the ideal rate for our sort of weight sits between 0.85 and 0.90. Again, adding 10ml of oil will firm up the final part of the stroke, which would stop the fork bottoming out if needed.  Using the cable tie round the stanchion for measurement, you should be aiming to have about 10mm of unused fork travel under road use.

I already had a Micron front paddock stand from a previous bike setup, but you could either:
  • Put axle stands under crash mushrooms (if you have them fitted), or:
  • Use the jack with a block of wood under the pipes.  Although not my preferred option, I believe plenty of others have used this approach without causing damage.

vinnyb

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Re: YSS PD valves
« Reply #11 on: 12 April 2019, 04:12:45 pm »

 Hi, thanks again for all your help. I'd decided to follow your advice and go with straight 15w oil, pity really cos Hagon sent a litre of 10w with the progressive springs that I tried and couldn't get decent ride out of, I changed the oil levels and preloads but they felt worse than the standard springs whatever I tried, hence the emus and linear springs. It would be nice to think that it'll be about right first time, having the benefit of your advice and experience has made it more likely.
 I don't know why I didn't think of axle stands. I haven't got bobbins but I've got engine bars that I can rest on them.
  Obviously I'll post how it's going. Thanks again for your input.
 
   

hopefiendboy

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Re: YSS PD valves
« Reply #12 on: 16 April 2019, 09:14:34 pm »
Did you modify the length of your fork spacer tubes for the mod?

vinnyb

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Re: YSS PD valves
« Reply #13 on: 16 April 2019, 10:59:39 pm »
  No, I didn't need to. As I said in an earlier post, the linear springs are 296mm whereas the originals are 316mm, the valves add about 16mm, so total length is actually about 4mm shorter than the old spring. I've got spare washers from the donor forks if I need them but I'm hoping the preload adjusters will be enough to make up the difference.

hopefiendboy

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Re: YSS PD valves
« Reply #14 on: 17 April 2019, 09:48:03 am »
Nice one. I suspected as much, it was just the slight discrepancy between the two I was concerned about. I dont have donor forks or spare washers :-)

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Re: YSS PD valves
« Reply #15 on: 17 April 2019, 09:58:55 am »

vinnyb

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Re: YSS PD valves
« Reply #16 on: 17 April 2019, 11:06:54 am »
 Hi, I don't know the specific model of bike the springs are for, I just phoned FireFox Racing and the guy I spoke to recommended the length and weight, I also got the PD valves from them. He also told me that I didn't need to drill the damper rods but I had already got the donor forks and I couldn't find anywhere online, where anyone had fitted them without drilling them, although the newer fitting instructions with the valves don't tell you to do it. Maybe you could give them a call and see if they tell you the same. Hope this helps.
« Last Edit: 19 April 2019, 09:22:11 am by vinnyb »

vinnyb

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Re: YSS PD valves
« Reply #17 on: 18 April 2019, 10:46:33 pm »
 Finally got the bike back down onto it's wheels today. Not ridden it yet but hopefully that'll happen tomorrow. Obviously I'll post how it goes if I get out on it. Thanks for all the advice.

hopefiendboy

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Re: YSS PD valves
« Reply #18 on: 19 April 2019, 09:15:36 am »
Just as an update it is the earlier sv650 fork springs that are required for this- 98-02 carb SV650 linear springs. I will be doing my forks over the next week hopefully :-)

@vinnyb will be interested to see how you get on / what you think !

vinnyb

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Re: YSS PD valves
« Reply #19 on: 19 April 2019, 09:56:37 am »

 Cool, good luck with it. Mine went quite smoothly, the only thing I had a real problem with was the damper rods turning as I tried to undo the bolts. I ended up holding them with a length of scrap wood hammered into the top. Are you replacing the copper washers on the bolts or reusing the old ones? They recommend replacing them but they're silly expensive from Mr Yamaha. I bought new ones from Ebay for £1.75 for 10. Have you got a torque wrench cos the bolts aren't quite as tight as you might think the need to be (30Nm)
 My mudguard bolts were a twat too and rounded as soon as I showed them a spanner so they're now stainless and copperslipped.
   Have fun, I'll be posting an update when I've ridden mine
 

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Re: YSS PD valves
« Reply #20 on: 19 April 2019, 11:03:25 am »
I was just going to reuse the copper washers- they dont appear to be deformed so fingers crossed. Ive taken the opportunity to strip and rebuild the forks completely along with re-spray and laquer so they now look like new. Will take pics along the way :-)

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Re: YSS PD valves
« Reply #21 on: 19 April 2019, 08:37:26 pm »
 Yeah mine could do with a respray but I was going to make sure they were set up properly before I do it, in case I chip or damage them while I'm messing about with them. I hope to get the front of the engine, radiator, frame cross rails and engine mounting bracket done this year. That'll be much easier with the front end off, so I'll maybe do the forks while they're out. The centre stand and torque arm need doing too and the wheels. I've bought the paint, it's time I seem to lack. The house needs work too.
« Last Edit: 20 April 2019, 08:17:05 am by vinnyb »

vinnyb

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Re: YSS PD valves
« Reply #22 on: 20 April 2019, 08:00:07 am »
 Just out of interest, what gap is there supposed to be between the top of the spring and the top of the fork when they're fully extended? My springs came about up to the threaded part of the leg.
« Last Edit: 20 April 2019, 08:16:09 am by vinnyb »

hopefiendboy

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Re: YSS PD valves
« Reply #23 on: 26 April 2019, 12:43:13 pm »
Just as an update it is the earlier sv650 fork springs that are required for this- 98-02 carb SV650 linear springs. I will be doing my forks over the next week hopefully :-)

@vinnyb will be interested to see how you get on / what you think !


Just to say that the fork springs arrived, they were exactly the same length as the original springs and therefore I had to trim the spring spacers by 16mm to account for the valve emulators.

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Re: YSS PD valves
« Reply #24 on: 29 May 2019, 06:35:24 pm »
any further on with this how did it ride im in the middle of collecting the parts to do it got the emulators and damper rods so will be doing it this weekend all being well