CBR600F front forks

[0l0dom0l0]

The forks on the cbr I've just picked up are so soft its like being on a sofa. They aren't returning to their full height either I don't think.

The bike is a 1995 registered but is actually a 94 model. However I'm pretty sure the 94 had preload adjuster etc. These forks don't, they have air valves at the top?

Does anyone know what year the forks are from?

Apparently I should be using 10 psi in the forks, which I am and it has improved things but there is still a long way to go. Also I've checked the oil level and that's fine so I'm abit stuck atm!

The bikes also got a slight judder/ chatter from the front end under heavy braking. Could this be from bottoming the forks out?
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CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.

[Vincent]

Might be an idea to get the springs out and measure them. The tollerances should be in the manual. If they're shot, look into fitting some progressive springs from Hagon or similar.

If the forks look like they've been stripped already, maybe they were put together wrong.

I might be wrong but 10psi sounds a bit high to me.
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Space Is Deep

[0l0dom0l0]

So you think its strip down time then?

What's the best way to keep everything cost effective?

Also what is it inside the fork that wears out that might need replacing? I'll definatly try some heavier oil. Although I don't actually know what year I'm buying parts for!

I was told 5-10 psi with recommended 6. Went to 10 to try and stiffen them up.
____________________
CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.

[finpos]

Perhaps almost unbelievably, I re-built a CBR that I had managed to stuff into the front of a Ford Fiesta years ago and had exactly the same problem. The replacement forks I got from the breaker looked similar but sagged like something very saggy.

They were also missing a couple of mounting lugs etc. so were clearly off a different bike but I never found out what; the breaker being as useful as can be expected.

I took the internals out of my bent forks and fitted them to the straight ones and that fixed it - no idea if the springs were different but the spacers at the top were much longer.

I've also got a vague recollection of the forks overall being too long but can't unfortunately remember how that worked out!

f.

[kali]

[Vincent]

[temeluchus]

I think the air forks are from the earlier jellymould CBR600s from the late 80s.

I believe all the earlier CBR600s and 900s can swap front ends.
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Some shite cruiser. Now with guns and FREEDOM!

[0l0dom0l0]

Thanks for all the replies.

I've found somewhere online that does Hagon progressive springs for £80 which I'm tempted by, although ideally I want to get a later model front end.

Will see what I fancy. Not fully decided on what to do with the bike yet!

Also the forks are from the original CBR's up to 90, when they changed. Looks like the CAT C must have been a front end smash up.
____________________
CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.