[PhilJ]

When I first get on mine, the front forks drop about one to two inches, with little or no resistance.  Is that an indication of needing oil?  Or maybe go on a diet.

None of the above, LJ.

When the bike is on the center stand or side stand there's very little weight on the forks. When you get astride it should do what you described.

My question arose because a multi viscosity oil didn't make sense to me.

I thought I got some very good answers so I'm going to find some fork specific oil. In your case, in Tonga, you may be at the mercy of your local shops. But really any oil will work, as in Vince's response.

[Vince]

     Larry, suspension has a certain amount of "sag" engineered in. Typically a street bike will sag about 10-20%. If you have 5" of travel that means 1/2-1" of sag. Dirt bikes run about 30%. This sag, or negative travel allows the suspension to maintain traction on the far side of a bump. With no sag the bike would tend to skate over bumps, particularly in a corner, often resulting in a spill.  Also, to set it up with NO sag would make the suspension impossibly stiff and unresponsive.
     If you have excessive sag you will not be able to fully utilize the suspension. You would get a mushy ride with constant jolts as the suspension bottoms out.
     The springs hold up the bike. The oil controls the spring. If you have too much or too little sag you need new springs. Then you need to adjust the oil weight and volume for the ride you want.

[LJRead]

Thanks for the replies.  The whole bike and its ride feel good to me, but I have no experience to compare it with, but mentally asked myself each time I got on and felt the initial sag, whether it needed oil - thanks, I'll just keep on riding (hoping it doesn't rain tomorrow!)

[clamp]

In another bike of mine I used corn oil for cooking, It works ok and of course is low cholesterol.

    I dont want to get on a save the world debate but no oil should be wasted. You got an oil can aint you?

      I have made my own creosote with a bit of diesel mixed into old engine oil. 

    It can also be used for mangie dogs, I good soaking in old engine oil kills the parasites.

     The dog quite enjoys the attention at first but then has different ideas,-- Dont let the dog in the house what ever you do.

     Ive used ATF as a hand cleaner and deisel as a mosquito repelant.

[Rick Sperko]

How is SAE 20 (non-detergent) compare to SAE 20W for fork oil. I just learned the W stands for Winter, not Weight.

Thanks,
-Rick

[Geirskogul]

     Ive used ATF as a hand cleaner and deisel as a mosquito repelant.

That's well and good, except that complex hydrocarbons are known carcinogens.

Anywhoo, when I first got my bike after a stop the forks would compress, but not come back up unless I popped them up manually, or went over some bumpy road.  I do weigh 250, but it still wasn't good.  Stole an idea from Rick about using a car antenna as a dipstick and found I had about 9" of oil in there, too low!  I just topped it off with some Type F ATF I had handy to the recommended 15", and it rides just fine.

Plus side is that it looks like I'm checking the "blood" of the bike with the red ATF, and red ATF is much easier to read on my "dipstick" than the stock clear oil it had in it.


That's thinkin' with yer dipstick, jimmy!   *smack*

[dogbone]

Is fork oil just hydraulic oil ?

[1Blackwolf1]

That's thinkin' with yer dipstick, jimmy!   *smack*

  I agree.

[clamp]

When I first get on mine, the front forks drop about one to two inches, with little or no resistance.  Is that an indication of needing oil?  Or maybe go on a diet.

       Both probably.

     Well what I do is walk across the road and by 2 bottles of motorcycle fork oil from the little accessories shop. They have a stand there with just about any oil you could think of, even synthetics. At 80 cents a bottle It is sold in 200cl  for easy calculation of quantity.

    My Suzi 1400 book says SAE 10 fork oil,   300 cl so I buy  3 bottles.

      Easy init?

     Auto   transmission oil is 62 viscosity