Wilsons Sandbox

A question on another group was asked as to whether the specified fork oil level is with springs in or out. My response was as follows and thought I'd post here for discussion purposes:

 

It makes a great difference in oil level. If the springs are left in the oil level will be far too low in effect since the oil level is predicated on the amount of oil displaced by the springs.  Some of us have discussed this subject because it should be obvious that different springs must result in different oil levels once the springs are installed. If that is the case, it might be better to measure the level with springs in place since this should reduce the variation of oil level when different springs are installed.  FWIW, the oil level affects the compression ratio of the air void above the oil. The higher the oil level, the greater will be the compression ratio and so the greater the spring effect of the air.  If one were to specify the oil level with spring installed (I have not measured this but have just face palmed), then one might reduce the compression ratio variation between various springs.  The empiricists are flying to the keyboard at this moment to point out a number of facts: 1) The KLR forks are very crude so it would need to be demonstrated that this effect actually makes a significant difference. I don't know. 2) Every rider is different as is every type of riding so one needs determine the best spring, oil viscosity, and oil level by experiment under actual conditions so any recommended oil level must be speculative. I think this holds the prospect of becoming an oil thread but there may be some useful discussion. Thoughts?