forks

[brad]

    Hea guys, im new to fourm and computers and could use some help.  I bought a used kx250 and id like to stiffen/raise the front shocks.  can I just add compressed air at the top fitting, or does it need to be nitrogen? What should the psi be?

[sandblaster]

Don't use compressed air, you need to use nitrogen.
What year is your bike?

[Motorrad]

Don't use compressed air, you need to use nitrogen.
What year is your bike?

whoa.. whoa....

Not if they are the front forks like he posted.....





Are you trying to lift the Rear of the motorcycle, or the front of the motorcycle

[sandblaster]

No nitrogen in the forks?
That's all I have ever used.
Then again I have never tried to raise or lower my bike by fork pressure, I have only put in the recommended amount.
The last bike I did this with was a 78 rm250 and if I'm not mistaken the manual recommended it.
Newer forks don't use it but I could swear the older style used it.
Then again it's been 30+ years and my memory could be doinked.
Why no nitrogen?

[Motorrad]

No nitrogen in the forks?
That's all I have ever used.
Then again I have never tried to raise or lower my bike by fork pressure, I have only put in the recommended amount.
The last bike I did this with was a 78 rm250 and if I'm not mistaken the manual recommended it.
Newer forks don't use it but I could swear the older style used it.
Then again it's been 30+ years and my memory could be doinked.
Why no nitrogen?

Guess we could eleborate on this more..

#1 we need to know the year of his KX250..

many of the motocross bikes from the 70's and early 80's were designed to have a "shot" of air in the forks.. (few of my old Huskys want it)

Anything Modern.. say.. 84 and up (just wrote down first number that came to mind)...    uses  ambiant air pressure..

Before you go for a ride... race.. etc.    you TOP OUT the forks... release the bleeders... and screw back in..   once suspension settles, you have some pressure due to compression..   and.. deffinatly once you start riding.. heat build.. which causes more pressure...

some FAST guys I know.. actually have to release pressure in the middle of the race, because they will blow out seals, just from heat and pressure buildup..





If your having to put a shot of Nitro  or air in your forks to make them ride how you want.. (stiffer, with less bottoming)   you need to add more oil to get a differant "air spring" volume...

If you just want to raise the bike up... you need differant fork springs. / preload on said spring.


Then again.. I could be wrong also    

[brad]

ok, some say nitrogen, some say oil/nitrrogen, some say air?  I was confused to start with guys now im almost hopeless.  if it helps its a 1985 kx, and the front shocks.

[sandblaster]

Ok, that will help.
I just found a manual for the 85 kx250.
The manufacture recommends KYB G-10 or S.A.E. 10W20.
Amount per side 550-558 mL or 18.6-18.9 oz.
Oil level from top of inner tube 178-182mm or 7.01-7.17 in.
No nitrogen or air is required.
But let me back up.
Why are you trying to raise the front end?
Is the front end bottoming out?

[brad]

thanks sandblaster, im starting to have second thoughts.  my original problem is the front end feels like it floats around.  kind of what it would feel like if the front tire was flat on a hard road. with no weight on the bike, i can lift the front forks about 4 in. before they top out.  i figured that was just to far down for the forks to start before i even get my(lets just say over 40) butt on the bike.

[sandblaster]

Hmmm, my guess is it's time for some new springs.
Oil level will also effect how they compress and rebound but no way should they compress 4" with just the bike weight.
Do you ever bottom out?

[brad]

No i dont bottom out, but i havent rode too much in the last 25+ years. Im taking it easy while I shake out the cob-webs. The front end goes down pretty far when I use the front brake.