Advice on front fork springs

[Dave20046]

Ah yes.

Different springs (and gen) but this may help you, usefully has torque values

https://www.youtube.com/watch?v=Cj-cb12BCRw

[pedro3178]

Thanks for the advice guys. With regards to parts, is it just the springs, oil and new dust seals to do the job or is anything else required for my gen?

[Bibio]

the SV forks on both gens check valves leak like a bucket with holes in it. this is why you weld the rebound holes, doing this lets you use a lighter weight of fork oil. if you dont weld the rebound holes you have to use too heavy an oil which will slow the reaction time of the stanchion down so you end up with a harsh ride as the rebound/compression cant move quick enough.


springs are to support the weight of the bike and the rider so the suspension is at the correct ride height.
oil is to dampen the movement of the springs.


yes you could drill and tap the rebound holes and put bolts in but they would need to be inserted from the inside of the damper tube with threadlock. the excess bolt coming out of the front would need to be dressed flush to the outside of the tube.


if all the above is done correctly damper rod forks can be about 90% as good as full cartridge and plenty good enough for road use.


emulators mainly control the compression. this is fine if your racing to stop dive during braking but road riding is different with the SV as you should not be relying on your brakes as much but instead using the engine braking and forward planning.


BTW sending the dampers via the post is a way round the lockdown.

[pedro3178]

Thank you very much for the explanation.

Would this be the hole you mean on this diagram that I have marked in red ?



I will try finding someone to do the weld for me, like you say, I can use the postal service.

[embee]

You'll get a huge improvement simply from the appropriate springs and decent oil, the old 80/20 rule applies (80% of the effect will come from the first 20% of the effort).

In my curvy SVS first I fitted 0.85kg/mm linear K-tech springs and Fuchs/Silkolene Maintain RSF 7.5W oil at about 100mm, didn't close off the rebound holes, and it improved the fork performance dramatically. I'm about 12st.
Sure it doesn't make it perfect, but the improvement is at a level where if it was like that to begin with you probably would be perfectly happy to live with it.

The Silkolene RSF oil has a high "viscosity index" (VI) compared to many other commercial oils, meaning it doesn't change viscosity as much with temperature as oil with a lower VI, the higher the better. I've tried other oils with lower VI and when cold it can feel like the forks are filled with wood. I get RSF from https://www.sportsbikeshop.co.uk/ usually. The RSF 7.5W is about the same viscosity as many other 10W oils. There is a good table on this page showing actual viscosities, http://peterverdone.com/wiki/?title=Suspension_Fluid

As the others say, choose the right springs for your weight and style. I would back the comments about selecting parts for ROAD use, you don't want track values for use on typical roads. Linear springs make life easier to get them right, unless you know what the characteristics of "progressive" springs are then you don't really have a hope of getting it near right, you're just guessing blind.

[Adam Ef]

Agreed. It's quite a process to get emulators set right. If I did it again I'd probably be happy with the right springs and new oil.

[Dave20046]

Originally Posted by Adam Ef

Agreed. It's quite a process to get emulators set right. If I did it again I'd probably be happy with the right springs and new oil.

To be honest by the time you mess about with emulators I'd be looking at the front end conversion.

On the rebound holes - bit rough, but https://www.amazon.co.uk/JB-WELD-MAC...7550530&sr=8-3 ?

[Adam Ef]

Originally Posted by Dave20046

To be honest by the time you mess about with emulators I'd be looking at the front end conversion.

I thought about getting another SV and doing the GSXR front end conversion. I ended up just getting a GSXR instead.


If I'd found a naked SV650 with GSXR front end already done though I'd have bought it.

[Dave20046]

Originally Posted by Adam Ef

I thought about getting another SV and doing the GSXR front end conversion. I ended up just getting a GSXR instead.


If I'd found a naked SV650 with GSXR front end already done though I'd have bought it.

Haha
I found mine remarkably easy. 3 or 4 hour job after sourcing the parts. Was cheaper than emulators too and so easy to adjust.

[pedro3178]

Originally Posted by Dave20046

On the rebound holes - bit rough, but https://www.amazon.co.uk/JB-WELD-MAC...7550530&sr=8-3 ?

Thanks. I’m going to get a braze torch and some copper rods and give that a go. I’m used to doing solder work so hopefully I won’t F up my forks