NC24 forks and brakes

[guppy]

Hi guys, i just bought a vfr400r nc24. it runs fine except under hard braking the forks seem to bottom out and go clunk-clunk-clunk. i posted up on the rgv forum (also got an rgv250sp vj23) and someone said to go here and ask. apparently the forks have oil and pressurised gas, and they might need re-pressurising. also apparently there was a classic motorcycle article about rebuilding the nc24 forks. does anyone have a scanned copy of this?

the brakes don't seem very good either. the lever pull is quite hard, but it just doesn't brake anywhere near as hard as my rgv. anyone experienced this?

[spooky]

Mate, REF.Fork rebuild, I had a link to that but it is not working now for some reason. Check out your fork oil level.All the specs for the nc24 are at the back of the haynes manual for the nc30. :) As for your brakes check out if the pistons are seized as they could be in need of new seals and cleaned and lubed slider pins.Be carefull with the bleed nipples as I have just rounded one of mine off. Use lots of easing/penetrating oil for 2 or 3 days on all fasteners before even trying to force them.
I ended up using a hot air gun And impact driver to get one of the cap screws for the pad retaining pins out.
Get yourself some HH rated pads, they are very good.

[guppy]

no worries, if you do manage to track that article down i'd be very keen to have a look. the forks definitely seem to be bottoming out i managed to find a copy of the nc24 specs from that haynes manual on the internet. never messed around with forks tho, so will have to do some research on what to do. rebuilt a few engines in my time tho - gotta love 2-strokes

rode it home from work last night and the brakes seem to be a bit better, maybed needed free-ing up due to lack of use. i'll lube the slider pins anyway.

[Cammo]

I reckon you should change the fork oil and seals, and the brake fluid (and pads depending), a good start to owning any used bike.

I don't think the forks are pressurised in any way.

[spooky]

There are valves at the top of the forks on mine, I was told to pump about 10 psi into them. Did'nt make much difference though. cant see much point in them as after a short ride they lost pressure. Was also told not to go over 12 psi as the seals could blow. Maybe some of the gurus on here could enlighten us about this?

[duncan]

I would be careful about pumping air into the air valves on top of the forks as you can easily blow the fork seals.I have got preload adjusters on my fork tops instead.I have also got heavier duty fork springs and heavier fork oil.I had a problem with clunking but discovered it was the left hand brake caliper mounts wearing.The caliper is supposed to pivot on the top mount and press a plunger attatched to the lower mount into the lower fork leg which obstructs the flow of the fork oil thus giving you increased compresion damping under braking.The mounts are prone to wear so if you grab hold of the caliper it will feel if it is loose.

[Neosophist]

iirc it's 8 - 12 psi in the front forks. use a bicycle pump, 1 - 2 pumps at a time as it dosn't take hardly anything to put the correct pressure in them.

if it's loosing air that quickly there's prob a leak somewhere.

In regards to checking fork oil it's probably easier to drain it and refil it with the correct amount, which is STD 10w forkoil, 389cc in the Right fork, 392cc in the Left fork, try that first and after some riding see if the oils getting past the seals (it'll be all over the stantions and bottom tubes if it is.)

If not try putting some pressure back into the forks. a bit of water over the valves after putting the pressure in will help identifiy a leaking valve.