fork oil

[nik_codling]

Hi Folks,

What's the standard weight fork oil for a 600? I've been performing a little pre-trackday fettling with the suspension on Emily's bike and it's not too bad now, but the forks are very harsh over big bumps. Difficult to avoid on the often bumpy British back roads.

I stuck new fork oil in it last year, but I can't remember what I put in! :rolleyes:

It's as if the dampers are suffering hydraulic lock - the fork oil is too thick and won't go through the damper valves when you hit a big bump. This is corroborated by the fact that it's not using all the suspension travel (1/2 to 2/3rds, even with my generous frame on board), but feels as though it's bottoming out when you hit a big bump.

Also makes the bike feel a touch nervous if you hit a bump in the middle of a bend - tends to push the front wide a bit, which isn't very confidence inspiring. My feeling is that softer damping would make it all round nicer to ride, and would be much better if it's wet.

So anyway, if anyone can advise on the fork oil weight I'd be grateful.

Ta,

Nik

[Scotty]

someone will tell you to get different springs soon

if you do end up changeing stuff take some time to get used to it again

[CK & AK]

std is usually 7.5 tho 10 is fine too (in our race bikes we run 5 - but this is NOT always the right thing for a road bike!)

What height of oil did you put in last year?
Check the book for the correct amount for height & quantity.

Put in too much and it makes it too solid on damping.

Nick, have you thought about changing the springs inside? this could make it softer if you need to, once you have checked the exisitng oil is correct.

Good luck:)

[steve wright]

7.5 is std but this seems a common problem on air cooled monsters. the forks seem soft at standstill and low speed bumps, but high speed damping just goes solid! I've heard "learned men" say the valving needs changing but this is expensive. i think the answer is stiffer springs so the damping is not hit so hard or fast and thus might cope with the lower work load and "eased on" pressure.
i'm putting stiffer springs in my 900s so i'll let you know what happens.
However if you're only getting that much travel it sounds like your air gap is too small/the oil level is too high. The quick fix is to suck 25mm worth of oil out the top of the fork with a plastic tube and see what difference it makes. You can easily adjust it this way, or add some back if you go too far.

[Zimbo]

Steve's fix above is well worth a try, although 25mm seems fairly extreme in one go, I'd be tempted to suck out about half that much as a starting point. I found my resprung showa forks were a little underdamped last year and added 15mm to each leg, which made a very noticable difference!

[Pedro]

As a general bit of information, I have a set of Hyperpro springs to put in my forks and they're supplied with 2.5 weight oil.

Ped

[nik_codling]

Hi Folks,

Thanks for all your replies, what a helpful bunch! :-D

Turns out there was too much oil in - I'd heard that it was just under half a litre of 10wt in each leg - turns out it's actually 380. The forks go up and down now! :chuckle:

Wow, what a difference!

The funny thing is the bike was like that when Emily bought it, so somebody else obviously made the same mistake as me!

Bit of a job syringing the oil out - had to take the fork caps off and take out the spring caps out, and remove the plastic spacer above the spring. Getting them re-assembled was tricky - aplying pressure to the spacer tube and getting the collets back in took a bit of thinking about, but Emily worked out a good way of doing it (my usual approach of colourful language abandoned in this instance!).

In hindsight it would have been faster to take the forks out and pour out the oil, but never mind - learnt something new - want your fork springs replacing? Me and Em will do them in about 10 mins each side!!

The riding experience is loads better. I suspect I might be inclined to replace the oil with 7.5wt eventually, but it's good enough for now. I'll see how Emily finds it first and we'll go from there.

cheers,

Nik

[Pedro]

- want your fork springs replacing? Me and Em will do them in about 10 mins each side!!



Good, get yourselves round to my gaff and fit my Hyperpros then!! I can provide tea and/or biccies for those not on a diet!:chuckle: :chuckle:


Ped

[nik_codling]

Good, get yourselves round to my gaff and fit my Hyperpros then!! I can provide tea and/or biccies for those not on a diet!:chuckle: :chuckle:


Ped

I seem to recall Chez Pedro does a nice line in bacon sarnies, although I guess you might not want to be messing the new kitchen up by actually cooking anything in it! :chuckle:

cheers,

Nik

[Pedro]

I seem to recall Chez Pedro does a nice line in bacon sarnies, although I guess you might not want to be messing the new kitchen up by actually cooking anything in it! :chuckle:

cheers,

Nik

Couldn't possibly live with myself if I provided bacon sarnies and you subsequently couldn't fit in your new leathers....:chuckle:

[nik_codling]

S'alright, they've got a little bit of growing room left in 'em yet! :chuckle:

[steve wright]

Pedro, who supplied your hyperpro springs, and are they just two rates or are they progressive all the way?

[Zimbo]

I'ver a feeling the Hyperpro ones are progressive, I've got a set of monorate K-tech springs in mine (£65 direct from K-tech, had to machine the spacers a little fo fit) or Harris performance are likely to have an Ohlins monorate set if you prefer, about £75 a set, measure the old ones and give them a call.
I'm 12 stone and the .85kg springs are just right.

[Pedro]

Pedro, who supplied your hyperpro springs, and are they just two rates or are they progressive all the way?


Bought them off SJR999 on here but should be available through decent dealers. Can't remember whether they're dual rate or progressive

Ped