Lowering fork oil under min level?

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10/5/2018 5:41 PM

I have a set of 47mm twin-chamber Showa forks that are ramping-up too firm at the end of their travel.

I guess that in a 'twin-chamber' (Showa spring & SSS KYB's) set of forks, the outer/lower chamber oil is only utilized for use in the bottoming-cone and progressive air-pressure rise adjustments (and to the non performance aspect of lubrication).

The upper chamber manages all the compression & rebound damping aspects.

Anyone see why I could not drop the oil quantity/level below the quoted minimum in the workshop manual? I can't see why not?

To see/feel the air pressure increase, I assembled the forks without the spring, I was surprised how much air-spring effect there was!

With the bottoming cone oil-lock-collar removed and the compression adjuster set to minimum, I was still not using all the travel !

I am 200 lbs and my 2-mile long test track has heaps of jumps.

What say those with fork knowledge?

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Melbourne, Australia. Current rides: '11 RMZ450, '84 CR500, '06 DRZ400, '79 KX250 with 400 engine, '06 GSXR1000 full Yosh racebike.

10/5/2018 9:36 PM

SAE 3 Shock oil inner cartidge and SAE 10 Fork oil outter

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10/5/2018 9:49 PM

Yes go for it. I wouldnt go crazy tho. Try 20cc less, it should be a noticable change

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10/5/2018 11:21 PM

JFerry wrote:

SAE 3 Shock oil inner cartidge and SAE 10 Fork oil outter

Yeh I run ISO11 (Belray HVI 3wt) in the inner chamber, but 10 wt would stop me using even more travel, over the ISO11 in the outer.

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Melbourne, Australia. Current rides: '11 RMZ450, '84 CR500, '06 DRZ400, '79 KX250 with 400 engine, '06 GSXR1000 full Yosh racebike.

10/5/2018 11:23 PM

rjg wrote:

Yes go for it. I wouldnt go crazy tho. Try 20cc less, it should be a noticable change

Yep that's what I think, I just took out 20cc, thanks. The manual say's 330cc is minimum, now is 310cc :-)

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Melbourne, Australia. Current rides: '11 RMZ450, '84 CR500, '06 DRZ400, '79 KX250 with 400 engine, '06 GSXR1000 full Yosh racebike.