fork ?

[gasmask]

i just had my front forks rebuilt...but the shop did not put any air in them...if i want them stiff how much air do i put in them?

[BigRedRunner]

At the risk of starting an argument, you're best to leave them alone. Heavier fork oil, different springs, or shims is the best way to stiffen things. I believe 10psi is the standard max for forks. What trike is this?

[OldSchoolin86]

At the risk of starting an argument, you're best to leave them alone.
I agree 110%! If you want stiffer forks put thicker oil in them. Air pressure doesn't have as nice of a feel and it adds to premature seal failure.

[gasmask]

I agree 110%! If you want stiffer forks put thicker oil in them. Air pressure doesn't have as nice of a feel and it adds to premature seal failure.
the bike is an 85 atc 250r/500....i had the shop use transmission fluid...should i redrain and change oil? which weight oil should i use....

[twgranger]

Use 15 weight fork oil.

[Power_Ram100]

Max psi for a Z fork is 8.5 psi but it says 0 psi is normal pressure. * dont wanna over pressurize it.

[EZ in NZ]

Personally, I wouldn't count on air or oil to stiffen them up much. They're 20 year old forks. The springs are probably getting a little tired. Try making some 1" pvc pipe spacers and put those in there to stiffen them up or if you have plenty of $$ - go for some performance springs. Spacers have worked well for me on different bikes over the years.

[Huffa]

If you want them supple for small bumps or low speed just raise the oil level in the fork tubes with the same oil you have in them.

What you do is take off both fork caps (with forks still on machine), take the springs out and leave forks bottom out. Now stick a tape measure down till it just touches the oil and see what you have in measurement. Check both 1st before adding because it's almost guarenteed that they will be off a bit. Just add a few CC's till you get the desired measurement. I guess you could also put the tape or whatever all the way down till it bottoms in fork for measurement also as that would probably be easier.

Really, that is the most precise way of knowing if the quanity is matched between tubes instead of just dumping the recommended CC's in. A 1/4" can make a big difference in the last part of the stroke. Forks can be on or off the bike to do this.

The amount the factory gives you is only a recommendation for people that don't know what their doing.

Just don't raise it too much or you can blow the seals. Try a 1/4 at 1st then a 1/8th after that if still not satisfied.

When testing make sure your using all your travel yet. A way you can do that is put a zip tie (fork boot must be off though) on one fork tube snug but yet not too snug so it will move. Simply ride the machine and see how far the fork pushes them up.

When you have the forks bottomed on 1st step of oil adding, make a mark with a piece of tape or something just above that point, that way you know how far they should go.

For overall stiffness (like said above) new springs (maybe heavier then stock) and thicker oil is a must. You can preload them but if you do it too much (too large a spacer) the spring will coil bind before you use all the travel.

Don't use air at all !! If you put say 3lbs of air in when cold, that can turn to 5lbs or so when hot and air has moisture in it also unless you have a compresser that takes it out.

If anything use them to bleed the air out every so often !!