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The amount of oil added to the fork is measured from the top of the tube down to the oil, with springs/spacers out and the fork tube fully compressed, right? I don't have the service manual in front of me, so I don't recall the exact measurement, but I know it's in there. If I'm running Ricor Intiminators, should I have those in when I set the oil level? I'd suspect yes.
And the most important question-- Is the oil level the same regardless of fork tube length? I'm installing 8" over tubes. If the factory measurement for stock is, for example 5", I still use that same number, but obviously I'll need more oil to get to that same level. Am I understanding this correctly?
I assume the oil level is important because the air above the oil acts as a secondary spring, so too low and it will have less resistance, and too high and it will hydrolock and not have full travel. Or blow out the seals.
Once you've changed the configuration of the the forks, the level pretty much goes out the window. You can set it at a level of whatever it's set to or whatever it is set to + 8 inches if springs and spacers are the same as stock. The whole idea is use enough oil for the damper to work and trap enough right amount of free space that that you don't hydralic the forks but have enough volume to add a progressive air spring to increase fork spring rate to help control bottoming.
The best thing to do is measure the volume of the parts not installed when setting the level and compare it to the voluum of the forks completely compressed. Don't forget to include the cap in the voluum estimate. I don't know what you want the final ratio should be but would think that it should be about 1/4 to 1/8 the volume of the assembly when it is fully extended with parts inside. IIRC the set of forks I did were about 1/6. They worked out pretty well. It was a 78 CB750 with emulators, using stock springs.
Here is what I used to measure the volume of the spring.
Once you've changed the configuration of the the forks, the level pretty much goes out the window. You can set it at a level of whatever it's set to or whatever it is set to + 8 inches if springs and spacers are the same as stock. The whole idea is use enough oil for the damper to work and trap enough right amount of free space that that you don't hydralic the forks but have enough volume to add a progressive air spring to increase fork spring rate to help control bottoming.
The best thing to do is measure the volume of the parts not installed when setting the level and compare it to the voluum of the forks completely compressed. Don't forget to include the cap in the voluum estimate. I don't know what you want the final ratio should be but would think that it should be about 1/4 to 1/8 the volume of the assembly when it is fully extended with parts inside. IIRC the set of forks I did were about 1/6. They worked out pretty well. It was a 78 CB750 with emulators, using stock springs.
Good point, I didn't consider that. I'm running aftermarket springs and of course longer spacers. I should be able to calculate the volume of the stock parts/stock tubes to see what the factory ratio is, and then compare it to to the volume of my aftermarket parts.
Yeah, the different springs change things. Ultimately, you need pretty much the same airspace volume when things are all assembled, assuming the travel stays the same.
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Fork oil level
