This is the assembly that sits between the clamp for the carbs and the o-rings that connect to the cylinder intake. Problem is they're made of plastic. I hit it with PBBlaster three times and it didnt help. Usually I'd torch it and suck beeswax into the threads, but that wouldn't be good on the plastic. And tricks on this? I suppose I could file my own bolt head edges, but I though I'd ask before I destroy this part.

http://www.bikebandit.com/oem-parts/2007-suzuki-gs500f/o/m16095#sch649446

#20?
Do you mean the screws holding the rubber intakes? They shouldn't be plastic. What evidence makes you think they are? And if your intakes are so hard they seem like plastic, that's an issue also.

I'm talking about the the intake assembly, #18. It's not made of metal. It looks like a composite plastic, whatever it is I doubt it could handle a torch.

Are yours held on with large Philips style head screws? I believe I used a #3 Philips bit (blasphemy to some) a Small quarter in ratchet with a 6mm socket. I really leaned into it and the little extra leverage did the trick.

That being said, those boots are supposed to be pliable.  If their rock hard they don't make a good seal to the carbs which invites air leaks, which leads to ==> If they need to be replaced anyway, heat them up.

yep, philips head. i'll give the ratchet a shot. thanks

Impact driver and the correct size Phillips bit will probably get it going.

Careful you don't strip the head trying to get it off.

Also careful not to use too small of a bit, which ordinarily results in stripping the head.