SV650S - Emulators in un-modified forks?

[aesmith]

Hi,

I need to run with my old forks for a little while I rebuild the "good" forks. The old forks are bog standard. Of course I can stick my decent spring into them which will help, but what I was wondering what how it would behave if I popped the YSS emulators in as well? I know it won't work as well as if the damper holes were drilled out but I'm not going to do that on the spare forks, nor would it be worth while dismantling both sets just now to swap the damper rods over.

So say for a couple of weeks (plus an MOT), which would work better - unmodified forks with 0.85 springs, or unmodified with 0.85 springs plus emulators?

I might just give it a try, the only problem is that getting the emulators out is a bit messy and wasteful.

Thanks, Tony S

[glang]

As I understand it there wont be much difference from standard as without drilling the holes not enough oil can flow to make use of the spring loaded 'valve' function of the emulators. The forks will still tend to thump when hitting bumps....

[aesmith]

I decided to give it a try, as I needed the bike back together for this morning. To be honest, I don't think it's much different from the emulators in the modified forks. If it makes the bumps harsher then there's not an awful lot in it. Or not to a less discerning rider like myself. For me the main benefit from the emulators is the improved compression damping so you don't immediately dive through all the fork travel when the brakes are applied.

Long term of course the modified forks will be back in service, but at the moment unmodified forks + linear springs + emulators is miles better than standard.

[Blapper]

Verrrry interesting....

[aesmith]

Yes. I find it difficult to make an exact comparison, and no bump is ever the same on my journey. One consistent test is our level crossing, if the bike runs over that making it feel like a series of waves rather than jolts then I'm happy. Similarly if I can feel the bike pushing back when I'm on the brakes, rather than just diving without resistance.

One odd thing is that there's a little less rebound damping, showing itself as a touch of overshoot. I can't think that can be anything to do with the emulators, maybe just because the forks are older. Unless the bleed hole in the top of the damper rod actually reduced rebound damping.

For completeness I should say that my set up is YSS emulators with two turns of preload, 8.5N/mm Ktech springs, and Hydraulic 46 oil.

[DomP]

For comparison mine are YSS emulators 2.5 turns, 0.85 Ktech springs and 7.5 weight oil. I'm 10st unclothed, incase you wondered!

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[Bibio]

Originally Posted by aesmith

Hydraulic 46 oil.

looking at the specs of that oil its thinning out too much as it gets hot. what this means is that in the start of the day your forks will feel stiff but give it 30miles and they will feel plush, give it 60miles and they will feel like pogo sticks. use a cheep hydraulic oil designed for agricultural use and you will get cheep results and you will never be able to dial in your suspension properly.

the quality of oil you put in your forks dictates how well your forks will feel as they warm up. the less change from cSt@40c to cSt@100c the more constant the dampening will be. fork oil is not just any old oil its designed to be used in ermmm forks and shocks.

[DomP]

Have to say since fitting my emulators my bike feels in my limited experience very good indeed

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[aesmith]

Originally Posted by Bibio

looking at the specs of that oil its thinning out too much as it gets hot. ...

Was only intended as a temporary measure using what I already had rather than blowing £15 a time trying different fork oils. 32 was too bouncy, 46 about right.

Will probably change to specific fork oil when I rebuild my good forks if I can work out the equivalent. By the way, what sort of temperature would be relevant, riding in Scotland? I can't believe the oil even hits 40 Deg C, let alone 100.

[glang]

I think the 40 and 100 degs were just references points - with damping any change in oil viscosity is bad and makes a big change in performance (unlike in engine or gear lube oil where its not so noticeable). Hence unless the oil temp can be kept constant (impossible as in any environment it warms itself squirting through the orifices) the only other option is to chemically manufacture an oil that minimises that viscosity change.