FOA bumpstop refill

anyone know how to properly fill FOA 2” bump stops with oil? Yes, yes I know FOA sucks, dont buy, bla, bla, bla. Point is, I already bought them last summer. They have actually done very well, they work well, hold pressure and haven’t leaked once. So I’m actually happy with them at this point. But, I wanted to go with 20wt up front. FOA suggested either revolving them or simply going with 20wt. So I have 20wt on the bench ready. Question is, FOA said “they need to be full when the bump stop is compressed”, but they refuse to elaborate or help any further. Is there a quantity? Like 150cc of oil? Or is it literally that easy, drain them, compress them and fill with oil until they top off? Can I do this through the large set screw on top? Or do I need to make a spanner wrench and take the body cap off? On top of all this, I guess I’m a bit confused. With shocks, you have a reservoir with a piston that keeps pressure against oil. There’s no piston or bladder in bump stops. So want actually forces oil through the valving? If the oil just sits on top of the valve, with pressure in that chamber, is that all that’s used? So the last bit of travel, the oil chamber basically hydrolocks then forces the oil through the piston, right? How does this work if I’m being told to fully compress the bump, then fill it? That means when it’s fully compressed, there’s not enough oil to be pushed through the valve? Or am I just overthinking this....

 

Thanks for the quick response guys! So they had 60cc of oil in the each. I was able to drain them, remove just the air valve cause the cap and set screw where NOT coming off. And in typical FOA fashion, one of the air valves broke off in the cap. So an hour later and a trip to Home Depot, and that’s fixed now. They used hella lot loctite on these threads, so heat if you’re going to remove them. They each took about 90cc of oil after draining and bleeding. 90cc filled the when compressed as per FOAs instructions and after bleeding them. Now I’ve got 20wt oil in my front bumps, we’ll see how this works.....

 

Wow... 20wt fluid and 250 psi makes for a DAMN good bump. And they’re quieter too. I may run 20wt in the rear too, maybe decrease the psi a bit and up the oil weight. Damn, this made a HUGE difference. Totally worth it....