Author Topic: Fork oil - amount, specifications ? (Read 18956 times)

Freza · « **on:** 27 October 2014, 11:37:20 pm »

Hi,

I'd like to change my fork oil (2003 fzs600), but don't know which oil to put and how much.

Here it says:

Quote

Use either of two methods: A) measure 465 ml per fork leg B) measure 132 mm air gap (room from the surface of the oil to the top of the fork without the springs and with the fork fully compressed) Note 1: It is very important to have the numbers correct and - even more important - the same at both sides. If you miss out on this, it may result in poor handling and even have disastrous consequences. Note 2: Measuring air gap is recommended over measuring volume, and not especially more difficult, it will be more precise and yield better results. You can use any measuring device dropped in at the desired length and fill until the oil slightly touches OR you can overfill and suck out the excess oil with a hose that you drop in at the specified depth. Note 3: Recommended oil is a grade 10W fork oil. Addendum: You can tweak you forks according to your liking, e.g. by putting 15W grade fork oil in or reducing the air gap by a few millimeters.

Is that correct or ?

darrsi · « **Reply #1 on:** 28 October 2014, 01:04:37 pm »

The air gap is more reliable.
10w oil is okay if you're a lightweight and don't carry much luggage, or a passenger regularly.
15w oil firms up the front end in a positive way and gives a more controlled feeling to it in my opinion.

Freza · « **Reply #2 on:** 28 October 2014, 03:11:57 pm »

I'm 80kg and don't carry luggage. Should I go with 15w anyway?

darrsi · « **Reply #3 on:** 28 October 2014, 06:20:17 pm »

In my personal opinion i would say yes.
If you simply don't like it then it just means changing it back to 10w but it made a big difference for me.
One of those things, if you don't try it you won't ever know.

Freza · « **Reply #4 on:** 28 October 2014, 07:40:11 pm »

I'll put 15w then.
I don't like loose front end anyway.
Thanks

Jules-C · « **Reply #5 on:** 29 October 2014, 09:02:00 am »

I never noticed much difference using 15w oil but filling to standard level then adding another 10cc oil made front end feel a lot better

Freza · « **Reply #6 on:** 29 October 2014, 10:11:45 am »

Not a bad idea. It probably loses a few cc when it settles...

darrsi · « **Reply #7 on:** 29 October 2014, 12:05:29 pm »

Quote from: Freza on 29 October 2014, 10:11:45 am

Not a bad idea. It probably loses a few cc when it settles...

I would change one thing at a time to be honest, there's still the small chance you may not even like it with 15w oil, and the levels are there for a reason.

mars696 · « **Reply #8 on:** 16 November 2014, 06:35:18 am »

Hi focs,
I 've got a 2001 fzs600 and i am changing fork oil with 15w.
There are two amount-air gap specs that i found:
1)98-00 models, 475ml -121mm air gap
2)02-03 models, 465ml - 132mm air gap

Which one should i follow?My forks are with adjusters on top.
Thanks,
Aris.

Jules-C · « **Reply #9 on:** 16 November 2014, 10:12:24 am »

With preload adjusters use the 02-03 details

darrsi · « **Reply #10 on:** 16 November 2014, 10:23:41 am »

Quote from: mars696 on 16 November 2014, 06:35:18 am

Hi focs,
I 've got a 2001 fzs600 and i am changing fork oil with 15w.
There are two amount-air gap specs that i found:
1)98-00 models, 475ml -121mm air gap
2)02-03 models, 465ml - 132mm air gap

Which one should i follow?My forks are with adjusters on top.
Thanks,
Aris.

If it's the first time you've used 15w oil then post your thoughts on if it feels better/worse/no change.
I'm pretty damn sure you'll prefer it though.

Freza · « **Reply #11 on:** 26 November 2014, 03:38:59 pm »

Yeah, I'm interested too. I'll change mine in a few months.

mars696 · « **Reply #12 on:** 26 November 2014, 06:02:57 pm »

Sorry for the late reply,but i wanted to "feel" the bike before i give a feedback.
As many before me have said,the 15w i believe is a "must" uprgade.At least for those who ride at bouncy-shity-not so good roads like me,here in my country.
I also upgrade my hadlebars,from renthal's ultra low to lsl's street bars,and the feeling i get from the bike is the best i ever got from it.Ofcourse sag settings were checked.
The lsl bars have less sweep and are lower than renthal's and with the stiffer front end it became spot on for me!
I plan also a future spring upgrade,as i like the positive upgrade of the front end.
As for the bars,i have an ktm's superduke headlight conversion,so i dont know if they will interact with the fzs fairing!
Overall a big YES from me!

Freza · « **Reply #13 on:** 29 November 2014, 12:26:20 pm »

Thanks, 15w it is then!

Sannox · « **Reply #14 on:** 01 February 2015, 10:17:45 pm »

Oddly enough, just bought some silkolene 15w today as I heard that it's easier to just replace the standard 10w oil with 15w for a better front end, will see what happens and post a response when all done. About to do a stripdown anyway, so will be a few months.

midden · « **Reply #15 on:** 01 February 2015, 10:40:29 pm »

Quote from: mars696 on 26 November 2014, 06:02:57 pm

Sorry for the late reply,but i wanted to "feel" the bike before i give a feedback.
As many before me have said,the 15w i believe is a "must" uprgade.At least for those who ride at bouncy-shity-not so good roads like me,here in my country.
I also upgrade my hadlebars,from renthal's ultra low to lsl's street bars,and the feeling i get from the bike is the best i ever got from it.Ofcourse sag settings were checked.
The lsl bars have less sweep and are lower than renthal's and with the stiffer front end it became spot on for me!
I plan also a future spring upgrade,as i like the positive upgrade of the front end.
As for the bars,i have an ktm's superduke headlight conversion,so i dont know if they will interact with the fzs fairing!
Overall a big YES from me!

playing devils advocate: wouldn't replacing old degraded 10w oil with fresh 10w oil give a improved feel anyway and if the case then any advantage gained in using 15w would come as extended service intervals

darrsi · « **Reply #16 on:** 02 February 2015, 06:54:19 am »

Quote from: midden on 01 February 2015, 10:40:29 pm

Quote from: mars696 on 26 November 2014, 06:02:57 pm
Sorry for the late reply,but i wanted to "feel" the bike before i give a feedback.
As many before me have said,the 15w i believe is a "must" uprgade.At least for those who ride at bouncy-shity-not so good roads like me,here in my country.
I also upgrade my hadlebars,from renthal's ultra low to lsl's street bars,and the feeling i get from the bike is the best i ever got from it.Ofcourse sag settings were checked.
The lsl bars have less sweep and are lower than renthal's and with the stiffer front end it became spot on for me!
I plan also a future spring upgrade,as i like the positive upgrade of the front end.
As for the bars,i have an ktm's superduke headlight conversion,so i dont know if they will interact with the fzs fairing!
Overall a big YES from me!
playing devils advocate: wouldn't replacing old degraded 10w oil with fresh 10w oil give a improved feel anyway and if the case then any advantage gained in using 15w would come as extended service intervals

Honestly?
Probably not.

Freza · « **Reply #17 on:** 23 February 2015, 10:15:20 am »

So, they told me about a local guy here, an experienced biker and mechanic (has over 30 years of experience). I've been trying to catch him to take a look at my bike and change fork oil for the past several months, but he was always busy with a queue of bikes waiting before me.
However, he just managed to take my bike.
The guy is a genius, immediately told me something's wrong with my carburetors. Then he turned some knobs below the carburetors (that I didn't even know existed) and immediately improved the irregularity and calmed the engine. After that he took it for a full service, but that's for some other topic.

What's important is that he changed my fork oil to Motul 15W and did something to forks, he said that now they act more like upside-down forks than regulars. Something that has got to do with oil being pumped up the damper, and not getting stuck down, which happened to me prior to this service. If I understood him correctly, he installed some tubule to aid that.
He also installed additional spacers to stiffen the spring a bit further.

All in all, the bike now rides like brand new, more stiffer but not unpleasant. It's a beauty, no more wobbling on road hollows, it feels razor sharp. I can't believe what difference this made. Combine that with a complete service and tuning of carburetors (+some other sundries) and you get one very happy man.
It's been raining here for few days now and I'm already going mad

darrsi · « **Reply #18 on:** 23 February 2015, 01:31:55 pm »

Very interesting, knobs on the carbs? Sure that wasn't just the idle knob?

Upgrading to a firmer oil AND adding things is a little bit forward of him in my opinion, I would've preferred to have been asked about that first to be truthful.

BUT, if you're very happy with the results then that's all that matters I s'pose.

Freza · « **Reply #19 on:** 23 February 2015, 02:02:24 pm »

Yes, if I understood correctly, they're used for tuning the mixture. The idle knob is on the side, these are under the carbs, not easily accessible. He said they were turned way too much, so the engine was receiving too much air, which caused difficult starting when hot and irregular idling.

Yes, but he was honest and said he went a few times for a ride and tuned the suspension to what he thinks is good in his opinion, so when I arrived he said to go and do a test drive to see if he should soften it up or leave it as it is.
Since I liked it, we left it as it is.

darrsi · « **Reply #20 on:** 23 February 2015, 05:10:52 pm »

Quote from: Freza on 23 February 2015, 02:02:24 pm

Yes, if I understood correctly, they're used for tuning the mixture. The idle knob is on the side, these are under the carbs, not easily accessible. He said they were turned way too much, so the engine was receiving too much air, which caused difficult starting when hot and irregular idling.

Yes, but he was honest and said he went a few times for a ride and tuned the suspension to what he thinks is good in his opinion, so when I arrived he said to go and do a test drive to see if he should soften it up or leave it as it is.
Since I liked it, we left it as it is.

Okay, so the carb mixture screws were adjusted accordingly, that's fair enough.

I'm not knocking him at all, although it probably sounds like I am, it's that he just sounds too good to be true that's all.

Freza · « **Reply #21 on:** 23 February 2015, 06:19:12 pm »

Exactly, the carb mixture screws. One of the previous mechanics screwed them up completely...

He's a legend around here, I'm so pissed I discovered him just now. I won't be taking my bike to anyone else than him anymore.

darrsi · « **Reply #22 on:** 24 February 2015, 01:26:48 pm »

Fair play, it's great when you have a decent trustworthy mechanic that you can rely on but at the same time is not out to rinse your wallet.
I had a brilliant mechanic 25 years ago who was an ex racer with a pure passion about bikes who worked from just a garage.
He just wanted what's best for your bike, and would fix stuff you didn't even ask for, I was gutted when he retired.

andybesy · « **Reply #23 on:** 26 February 2015, 07:18:53 pm »

I had my fork seals replaced on Wednesday, and took the opportunity to go with 15 weight oil while at it.

Haven't been able to get out and about yet beyond the ride home, but my initial impressions were that it felt much more firm and precise. I'm 14.5 st and do a lot of heavy laden touring.

Will be out two up over the weekend and off up to Scotland in couple of weeks so will report back then.

Ps) I'm also chuffed to have found a great new mechanic, 50 labour I thought was good and he was kin kind enough to let me observe as an amateur keen to learn. I know enough to know a good job when I see one, extra care taken throughout, greased Speedo, cleaned forks etc.

Andy

Freza · « **Reply #24 on:** 26 February 2015, 10:25:18 pm »

Your initial impressions are correct

Try it through the bends now, it feels much more solid, no bobbing or chewing through hollows while leaning, etc.