Fork Oil Level

[donkason]

I am doing my first of many services on my 07 Gixxer 750 forks. I have Sonic Springs 1.1 kg going in and Maxima 5wt as it is as close to OEM as I can get off the shelf.

The manual states 112mm but in my search I've turned up a lot of rambling about the subject, but nothing solid. A Dave Moss video mentioned 130mm for street, which is a far cry from 112mm. I know the effects of more oil/less airspace = progressive stiffness and less oil/more airspace= a more linear compression.

Past that I'm still looking for some input on if I need to adjust the fluid height to suit track riding. I'm not a big break grabber either.

Any ideas?

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[blue03636]

You need to get the level from a gsxr repair manual. The 112 mm or whatever is a measurement from the top of the fork tube.

[donkason]

You need to get the level from a gsxr repair manual. The 112 mm or whatever is a measurement from the top of the fork tube.

Correct. That is where I got the 112 from. I downloaded the service manual.

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[blue03636]

That's the number then. Not sure if moss was giving info for your specific bike or not. If you have the manual that's what you need.

[gixxie750]

will look in the am. does not matter what spring. I think the 130 is on,but let me look at notes

[Moto-Brian]

130 is normal, but understand that at each track, oil level can be different. I am running 120 at one track and 130 for example at another. Depends on conditions and track, really. Oil level is a tuning tool as much as springs are...

I would also assume that you bought fork extender caps for your 750? If not, DIRE need of them for that chassis...

[blue03636]

So Brian, yes I'm thread jacking, do you run a higher level at bumpier tracks?

[Tpoppa]

130 is normal, but understand that at each track, oil level can be different. I am running 120 at one track and 130 for example at another. Depends on conditions and track, really. Oil level is a tuning tool as much as springs are...

I would also assume that you bought fork extender caps for your 750? If not, DIRE need of them for that chassis...

Interesting. I thought tuning by oil level was mostly and old school way to adjust compression and rebound before the days of fancy schmancy adjustable suspenders.

Does changing fork oil level feel different than adjusting rebound/compression?

[donkason]

So Brian, yes I'm thread jacking, do you run a higher level at bumpier tracks?

No threadjack here. Ima learn something:thumbup: This KTM Brian guy seems to know a thing or two. Maybe he should go on forums and help the locals sort out their rattle traps.

I have the caps on my short list. Those will be purchased over the winter. For now I have them flush mounted with the top mount.

I run Mid-O and will do other tracks next year. What conditions merit what type of fork oil levels?

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[r1crusher]

Drop the forks in the triples 5mm and add 10mm to the rear shock if you don't already have that done.

Edit: you should recheck your sag after this also.

[donkason]

Drop the forks in the triples 5mm and add 10mm to the rear shock if you don't already have that done.

Edit: you should recheck your sag after this also.

Is the 10mm in relation to the stock tire height? I have 180/55 Pirelli slicks on the way and they are taller on average than a lot of other tires. So if my Pirelli's are say 2mm taller than the OEM tire should I shim 8mm instead?

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[r1crusher]

Your tires circumference will def. play a roll in setting it up. I don't know if 2mm difference will be enough to cause you major concern but in the end yes, I believe you'd take that difference out of the shim at the top of the shock mount. It's all about keeping the geometry of the bike in it's "sweet spot".

Brian can also verify this as well if he is able to get his geriatric ass to the keyboard.

[Moto-Brian]

Yes, I run different oil levels to help sort through different tracks. I actually run less oil at Nelson and more at Mid-O... Dunno if that works really, but seems to. I run less pre-load at Nelson as well. Wrobel trick and it actually worked!!!

As for the GSXR ride and fork height. Dropping the forks flush in the triples isn't enough. Thus, the need for extending caps. Actually, would have to look at notes on the rear eye to eye on the shock, but 10mm doesnt sound too far off, I suppose. I know we would use spacers and keep the bottom threads exposed to a minimum for adjustability and stability.

[gixxie750]

Gsxr rear EYE TO EYE is 327 with 55 tires and 325 for 60 tires. 10mm of ohlins extender showing above tree. Or with OEM forks 5mm down under the top tree(not safe). redneck way is have top tree milled down 5mm on the stem and then run forks flush. I run my 20mm oil level at 160mm down with springs out.

[blue03636]

Ok, I ask as I had less oil at nelsons early this year and couldn't get the front to quit chattering. I filled it to ohlins spec and it was better so I thought maybe more would be even better. Hell who knows maybe I was way too low.

[crazbiker4]

Hey Mike,

Race Tech gives the suspension specs on their site... even the oil level (they say 120mm) which you can use as a starting point.

http://racetech.com/ProductSearch/2/Suzuki/GSX-R750/2006-07

[donkason]

Research ninja Joe!!! That's where I'll start and see how it feels.

Thanks bro!

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