Linear or progressive front springs?

[Geodude]

I know there are loads of threads on this but most are old and I wanted an up to date answer on linear or progressive springs ;)

99 sv650N with rider weight of 12-13 stone in birthday suit (varies when homebrew is available :D ) so what's my options (no high cost options please as I'm always skint) and where do I buy them?

I'm not a fast or hard rider and don't do track days and have had my sv for 8 years and never changed fork oil or stripped them so have no idea what's inside them yet until I open them up. So I'm gathering info for when I do. The reason I'm looking into it all is the dust seals are being pushed out by rust so will need to look into that anyway.

Thanks in advance

xGx

[ophic]

Mostly smelly grey water on the inside, I would guess.

Simply stripping them and replacing the oil with something heavier will make a difference and is fairly easy and cheap to do, although takes a bit of time. I followed a guide by Delboy's Garage on youtube and I followed his suggestion of using bits of PVC pipe tools and they seem to work pretty well. I made it even cheaper by using a hosepipe clip rather than his hefty bracket.

Half the job is getting the bike securely supported with the front off the ground.

Replacements springs are easy to fit once you've got them apart but aren't that cheap unless you can source them 2nd hand. Linear or progressive is down to personal preference, except that if you want to fit emulators, you have to use linear. Stock are progressive, I think.

[R1ffR4ff]

Like Ophic says just change the Fork oil for some medium weight Fork oil usually sold as 15w.I hover around the same weight as you and the front forks on my SV are way better than on my old Honda 500s so I've no intention of changing them or the springs to date.I ride fast sometimes and also on,"Goat Track" small country roads.

The difference to my Front suspension on my Old Hondas moving from the crappy ATF that they used in the 80s to 15w fork oil made the machines corner like they were on rails and gave a fantastic feeling of security when riding.I suspect the Fork oil in my SV650 has been changed to 15w Fork oil.

As I've no complaints with their performance at the moment I'm not intending to change the Fork oil for now but by experience know when I will have to and will use 15W/Medium fork oil.It's a common cheap upgrade on the US forums :)

When I need to do the job I've already bought a Front paddock stand/lifter which I also use to service my Front brakes.



http://www.ebay.co.uk/itm/Black-Pro-Range-Motorcycle-Motorbike-Front-Head-Stock-Paddock-Stand-Ghostbikes/400926866152?epid=1936939782&hash=item5d591a7ae8:g:SjIAAOSwB9hZ4Nge


https://i.imgur.com/eZZAYY2.jpg


VkLKwot-9ek

[ophic]

My paddock stand clips my fairing.

Shouldn't be an issue on a naked bike though.

[R1ffR4ff]

My paddock stand clips my fairing.

Shouldn't be an issue on a naked bike though.

Cool :)

These devices make servicing a joy and not a chore IMHO.I've had my pads off twice since last April when I put my SV on the road as I like to keep my pads de-glazed and ultra clean and lube the calipers/pistons etc.

Simple maintenance saves hassle and money in the long run :p

[Markylemin]

+1 to that. I have exactly the same stand.
I'm sure my fork oil is looooong overdue replacement too.

[Bibio]

linier springs.

hardest part is taking the damper rod bolt out the bottom and a windy gun is recommended.

remove mudguard and callipers.

remove front wheel.

loosen just the top pinch bolts on the yoke.

loosen the fork caps.

loosen each lower yoke pinch bolts then remove each leg one at a time.

lift the dust seal out the way then remove the retaining springs for the seals.

get some newspaper and lay it out on a bench.

remove the top fork caps and take the springs and washers out then put them on the newspaper then empty the oil out.

take the damper rod bolts out.

grasp the stanchion and lower fork leg and using force slide the stanchion up against the seals like using a 'slide hammer' till the seals pop out with the stanchion and the two parts of the fork are separated.

take the damper rod out then take it to your local welder and ask them to weld up the tiny holes at the top of the damper rod. dress the welds.

lay your new springs next to the old ones and measure the difference in length and if there is then cut the top spacer down to accommodate the new spring length.

when assembling use silkolene RSF pro 10w oil. pour 500ml into each leg and pump the stanchions up and down a good few times then set oil height (without springs in) to 97mm.

[embee]

Best thing I ever did for my curvy was fit new linear springs. The stock springs were too soft even for my 12st. I fitted 0.85kg/mm (8.5N/mm) from http://www.ktechsuspension.com/
They are very helpful, worth a phone call. They even offered to exchange them for a different rate if I didn't like them. Not cheap at around £80 odd (a few years ago) but excellent value for money mod, stops the sogginess.
I'd second the recommendation for Fuchs/Silkolene RSF fork oil (now called "Maintain" RSF, used to be called PRO RSF). Personally I use their 7.5W which according to the table here http://www.peterverdone.com/archive/lowspeed.htm is very comparable to most 10W oils (35cSt). With the right springs you don't need to try to fudge the system by putting thicker oil in (which doesn't fix the real problem anyway, which is the soft springs).
Emulators are a nice mod, but frankly you'll get most of the advantage simply by getting the appropriate springs with some fresh oil. Tuning the emulator discs and valve spring rate/preload is another set of questions altogether.

[Bibio]

7.5w is my recommendation if your going to mix it with some 20w to get the rebound set correctly but thats for people who want it 'spot on'. given the amount of forks i have done the 10w is pretty near the ball park for most folks. its rebound you need to concentrate on rather than compression. without welding up the rebound bleed holes on the dampers you need to go up to 15-20w which completely messes with the compression and turns the forks like steel rods instead of suspension.

why weld the rebound bleed holes.. due to the SV check valves leaking like a sieve.

[Geodude]

Thanks for replies :D Hmm seems a bit too complicated for me to do and I wasn't planning on having to strip them to pieces, more like just putting oil and springs in as I don't have a leak or anything other than a bit of rust pushing up the dust seal a bit. Might just leave them alone as ive neither the skill or funds :(

Cheers all :smt054

[maviczap]

Just go with changing the oil and springs Geo, it'll tighten up the front end for the better.

Bibs suggestions are the gold standard upgrade, just go for the bronze upgrade.

[ophic]

Mine looked terrible for years until one started leaking. Then I changed the seals. Then I crashed it. :mad:

[johnnyrod]

The stock springs are unbelievably rubbish. Linear is a better choice if you mainly ride solo, progressive can be useful if you ride a lot with a pillion. I would go for 15W oil. Changing the oil can be a pain, strictly you should take the fork legs out and tip them up, but there are threads on here about a sort of suction tube instead. Support the front end, take the fork cap off, remove the spacer etc., suck out fork oil. Replace oil and get the air gap right - about 105mm I think from memory, with no springs and the fork leg fully compressed (which is easier to do with the forks out, or at least take the front wheel out so you can push them up and down individually). Changing springs is simply a case of taking off the fork tops and pulling the springs out. If you don't already have the preload adjuster tops from later curvies them this is a good time to fit them.

[Geodude]

Sorry if this is a stupid question (which it probably is) but is there a top and bottom to a k tech spring? Point and laugh if it makes you feel better :smt090

Ps Thanks for all the pointers :D

[Bibio]

Sorry if this is a stupid question (which it probably is) but is there a top and bottom to a k tech spring? Point and laugh if it makes you feel better :smt090

Ps Thanks for all the pointers :D

yes and no...

the rate of the spring should be etched on one end, that end should go to the top for easy identification. if there is a tightening of one end of the spring (closer coils) then that end usually goes to the bottom.

excuse the spelling i dont have a spell checker installed yet... lol

[Geodude]

As usual Mr Bib's sir you have brought forth your mighty wisdom to save the feeble minded, I bow to you my liege lord :joker:
I owe you one of these

https://i.imgur.com/x9Ztioh.jpg

but it will probably end up being one of these :p

https://iheartdogs.com/wp-content/uploads/2016/08/female-dog-mounting.jpg

Seriously though, thanks all :D

[Geodude]

Is there anything I should use to clean out the old manky oil or just pump them and leave them upside down to drain out?

[maviczap]

Just turn them upside down and let them drain, give them a pump to help any out

[Geodude]

Why thank you kind Sir :)