Join Date: Jul 2007
Location: Collinsville IL (by St Louis)
Here's the skinny,
Just because 2 fork oils SAY the same wt they more then likely will not be. You have to go by viscosity, NOT by oil wt. When companies build the valving, they base it off a certain viscosity. So first, if you didnt check the viscosity of Repsol Fork Oil vs Kawi OEM oil you've changed the way the valving will work. Then by adding different oil with different viscosity it's altering it more. Is it the end of the world? No not at all. Will it affect the way the valving works? Possibly, but you wont know until you go ride it. I would recommend filling the forks to the required oil level with mismatched oil instead of stealing from the second leg. It's a lesser of two evils.
Changing Oil levels is a tuning variable like Kman pointed out. If you made them level you would be 15mm lower in each leg. Is that bad? Not really, Ive dropped oil in bikes I've tuned 20mm before without issue. BUT there was a reason why I was doing it. By lowering the oil you COULD, but not guaranteed, have the possibility of bottoming out your forks. The air gap helps as a pressure cushion so to speak as you get to the bottom of the fork stroke. This is why adding the normal amount of mismatched oil is better than possibly bottoming the forks.